Piling Handbook, 8th edition (revised 2008)
Foreword
Welcome to the 2008 revision of the Eighth Edition of the Piling
Handbook. ArcelorMittal is the world’s number one steel company
with 310,000 employees in more than 60 countries, and a crude
steel production of 116 million tonnes in 2007, representing
around 10% of world steel output. ArcelorMittal is also the world’s
largest producer of hot rolled steel sheet piles (HRSSP), and
market leader in foundation solutions. From its plants in
Luxembourg, ArcelorMittal Belval and Differdange produces
around 680,000 tonnes of steel sheet piles that are sold
worldwide through ArcelorMittal Commercial RPS (Rails, Piles &
Special Sections). Since 2006 ArcelorMittal Commercial RPS has
integrated the sales of Dabrowa sheet piles produced in Poland,
and starting 2008, after a major investment, the new sheet pile
sections from Rodange in Luxembourg. This gives ArcelorMittal a
production capacity of around 1 million tonnes of foundation
solutions, which includes cold rolled steel sheet piles and
combined wall systems.
In addition to offering the most comprehensive ranges of steel
sheet piling, ArcelorMittal recognises the high importance of
technical support for its foundation products. The Piling
Handbook is intended to assist design engineers in their daily
work and act as a reference book for the more experienced
engineers. The eighth edition of the Handbook includes
substantial updates, particularly in areas such as Sealants, Noise
& Vibration and Installation. The 2008 revision contains all the new
sections available beginning of the second semester of 2008. This
handbook reflects the dynamism of the foundations industry, and
is evidence of ArcelorMittal's commitment to customer support.
ArcelorMittal Commercial RPS’ mission is to develop excellent
working partnerships with its customers in order to consolidate its
leadership in sheet piling technology, and remain the preferred
supplier in the marketplace.
We sincerely trust that you will find this Handbook a valuable and
most useful document, and we look forward to working together
with you on many successful projects around the world.
Emile Reuter
Vice President
Long Carbon Europe
Head of Sales and Marketing of
Rails, Piles and Special Sections
Boris Even
Commercial Director
ArcelorMittal Commercial Rails,
Piles and Special Sections
© ArcelorMittal Commercial RPS 2008
Foreword
Product
information
1
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Piling Handbook, 8th edition (revised 2008)
Product information
Contents
1.1
1.2
1.3
1.4
1.5
1.6
1.7
1.8
1.9
1.10
1.11
1.12
1.13
1.13.1
1.13.2
1.13.3
1.13.4
1.13.5
1.14
1.14.1
1.14.2
1.14.3
1.14.4
1.14.5
1.15
1.15.1
1.16
1.16.1
1.16.2
1.16.3
1.16.4
1.16.5
1.16.6
1.17
1.17.1
1.17.2
1.17.3
1.17.4
1.17.5
1.17.6
1.17.7
1.17.8
Introduction
Typical uses
Steel qualities
Product tolerances
Section profiles
Maximum and minimum lengths
Interlocking options
Handling holes
Plating to increase section modulus
Plating to enhance durability
Corners and junctions
Stacking of sheet piles
Z profile piles
Z profile piles – Dimensions & properties
Interlocking in pairs
Crimping and welding of interlocks
Pile form
Circular construction
U profile piles
U profile piles – Dimensions & properties
Interlocking in pairs
Crimping and welding of interlocks
Pile form
Circular construction
Straight web piles
AS-500 straight web piles – Dimensions
& properties
Combined wall systems
HZ/AZ pile system
Box piles
Special arrangements – CAZ + AZ combinations
Combined walls with U-type sections
Load bearing foundations
Jagged walls
Cold formed sheet piles
PAL and PAU sections – Dimensions & properties
PAZ sections – Dimensions & properties
Trench sheet sections
Threading options
Sheet pile assembly
Thickness
Handling holes
Tolerances in accordance with EN 10249 Part 2
Page
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3
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6
6
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8
9
9
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15
16
16
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17
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25
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49
50
Piling Handbook, 8th edition (revised 2008)
Product information
Piling Handbook, 8th edition (revised 2008)
Product information
1.1 Introduction
Steel sheet piling is used in many types of temporary works and
permanent structures. The sections are designed to provide the
maximum strength and durability at the lowest possible weight
consistent with good driving qualities. The design of the section
interlocks facilitates pitching and driving and results in a
continuous wall with a series of closely fitting joints.
A comprehensive range of sections in both Z and U forms with a
wide range of sizes and weights is obtainable in various different
grades of steel which enables the most economic choice to be
made to suit the nature and requirements of any given contract.
For applications where corrosion is an issue, sections with
minimum thickness can be delivered to maximise the effective life
of the structure. The usual requirements for minimum overall
thickness of 10 mm, 12 mm or 1/2 inch can be met.
Corner and junction piles are available to suit all requirements.
1.2 Typical uses
River control structures and flood defence
Steel sheet piling has traditionally been used for the support and
protection of river banks, lock and sluice construction, and flood
protection. Ease of use, length of life and the ability to be driven
through water make piles the obvious choice.
Ports and harbours
Steel sheet piling is a tried and tested material to construct quay
walls speedily and economically. Steel sheet piles can be
designed to cater for heavy vertical loads and large bending
moments.
Pumping stations
Historically used as temporary support for the construction of
pumping stations, sheet piling can be easily designed as the
permanent structure with substantial savings in time and cost.
Although pumping stations tend to be rectangular, circular
construction should be considered as advantages can be gained
from the resulting open structure.
Bridge abutments
Abutments formed from sheet piles are most cost effective in
situations when a piled foundation is required to support the
bridge or where speed of construction is critical. Sheet piling can
act as both foundation and abutment and can be driven in a
single operation, requiring a minimum of space and time for
construction.
Road widening retaining walls
Key requirements in road widening include minimised land take
and speed of construction – particularly in lane rental situations.
Steel sheet piling provides these and eliminates the need for soil
excavation and disposal.
Chapter 1/1
Piling Handbook, 8th edition (revised 2008)
Product information
Basements
Sheet piling is an ideal material for constructing basement walls
as it requires minimal construction width. Its properties are fully
utilised in both the temporary and permanent cases and it offers
significant cost and programme savings. Sheet piles can also
support vertical loads from the structure above.
Underground car parks
One specific form of basement where steel sheet piling has been
found to be particularly effective is for the creation of underground
car parks. The fact that steel sheet piles can be driven tight
against the boundaries of the site and the wall itself has minimum
thickness means that the area available for cars is maximised and
the cost per bay is minimised.
Containment barriers
Sealed sheet piling is an effective means for the containment of
contaminated land. A range of proprietary sealants is available to
suit particular conditions where extremely low permeability is
required.
Load bearing foundations
Steel sheet piling can be combined with special corner profiles to
form small diameter closed boxes which are ideally suited for the
construction of load bearing foundations. Developed for use as a
support system for motorway sign gantries, the concept has also
been used to create foundation piles for bridges.
Temporary works
For construction projects where a supported excavation is
required, steel sheet piling should be the first choice. The
fundamental properties of strength and ease of use - which steel
offers - are fully utilised in temporary works. The ability to extract
and re-use sheet piles makes them an effective design solution.
However, significant cost reductions and programme savings can
be achieved by designing the temporary sheet pile structure as
the permanent works.
Chapter 1/2
Piling Handbook, 8th edition (revised 2008)
Product information
1.3 Steel qualities
Hot rolled steel piling is supplied to EN 10248 Part 1 to the grade
designations detailed below.
Table 1.3.1 Steel qualities - Hot rolled steel piles
Grade
Min Yield Point*
Min. Tensile strength*
N/mm2
N/mm2
Minimum elongation
on a gauge length of L0
= 5.65 √S0
%
S 240 GP
240
340
26
S 270 GP
270
410
24
S 320 GP
320
440
23
S 355 GP
355
480
22
S 390 GP
390
490
20
S 430 GP
430
510
19
460
550
17
Mill specification
S 460 AP
* The values in the table apply to longitudinal test pieces for the tensile test.
S 460 AP (Mill specification) is also available but please contact
ArcelorMittal Commercial RPS before specifying.
Steel grades with increased copper content offering higher
durability in the splash zone as discussed in the Durability chapter
can be supplied upon request.
Steel grades compliant with other standards (i.e. ASTM, JIS ) and
special steels are also available by prior arrangement.
Cold formed sheet piling is supplied to EN10249 Part 1 to the
grade definitions detailed below.
Table 1.3.2 Steel qualities - Cold formed steel piles
Grade
Min. yield
strength
Tensile
strength
Min.
elongation
N /mm2
N /mm2
%
S 235 JRC
235
340 - 470
S 275 JRC
275
410 - 560
S 355 JOC
355
490 - 630
Former references
France
Germany
U.K.
Belgium
26
E 24-2
St 37-2
40 B
AE 235-B
22
E 28-2
St 44-2
43 B
AE 275-B
22
E 36-3
St 52-3 U
50 C
AE 335-C
Chapter 1/3
Piling Handbook, 8th edition (revised 2008)
Product information
1.4 Product tolerances
Hot rolled sheet piling products are supplied to EN 10248 Part 2
unless an alternative standard (i.e. ASTM, JIS ) is specified.
Fig 1.4
Z piles
U piles
t
H piles
t
Straight web piles
t
s
t
s
h
h
h
s
b
b
b
b
Table 1.4
Height
Width
Single piles
Interlocked piles
Z piles
h < 200mm
± 5mm
200mm < h < 300mm
± 6mm
U piles
h < 200mm
± 4mm
H piles
h < 500mm
± 5mm
h > 300mm
± 7mm
± 2% b
± 3% nominal width
h > 200mm
± 5mm
± 2% b
± 3% nominal width
h > 500mm
± 7mm
± 2% b
± 3% nominal width
Wall thickness
Z piles
t ≤ 8.5 mm
± 0.5 mm
t > 8.5 mm
±6%
s ≤ 8.5 mm
± 0.5 mm
s > 8.5 mm
±6%
U piles
t ≤ 8.5 mm
± 0.5 mm
t > 8.5mm
±6%
s ≤ 8.5 mm
± 0.5 mm
s > 8.5mm
±6%
H piles
t ≤ 12.5 mm
+2 / -1 mm
t > 12.5 mm
+2.5 / -1.5 mm
s ≤ 12.5 mm
+2 / -1 mm
s > 12.5 mm
+2.5 / -1.5 mm
Straight
web piles
t ≤ 8.5 mm
± 0.5 mm
t > 8.5mm
±6%
All sections
Straightness
≤ 0.2 % of pile length
Length
Squareness of cut
Mass
± 200 mm
±2%b
±5%
Cold formed tolerances can be found on page 1/50
1.5 Section profiles
Chapter 1/4
Drawings of all the pile sections available from ArcelorMittal are
located at the following website
www.arcelormittal.com/sheetpiling
Sheet pile sections are subject to periodic review and minor
changes to the profile may result. It is, therefore, recommended
that users visit the ArcelorMittal Sheet Piling website to ensure
that they are using the latest pile profiles.
Piling Handbook, 8th edition (revised 2008)
Product information
1.6 Maximum and Minimum lengths
Steel sheet piling can be supplied in lengths up to 31 m (HZ piles
are available up to 33m long) but particular care will be required
when handling long lengths of the lighter sections.
Should piles be needed which are longer than 31m, splicing to
create the required length may be carried out on site.
When short piles are to be supplied direct from the mill it may be
advantageous to order them in multiples of the required length and
in excess of 6m long with cutting to length being carried out on site.
When considering piles at either end of the length range, we
recommend that contact is made with one of our representatives
to discuss availability.
Following table summarizes the maximum rolling lengths of the
different sections:
Section
AZ
31
AU, PU
31
PU-R
24
GU sp1) GU dp1) AS 500 HZ
24
22
31
33
1) sp = single pile, dp = double pile
RH / RZ
24
OMEGA 18
16
C9 / C14
18
DELTA 13
17
1.7 Interlocking options
AZ, AU, PU, PU-R and GU sheet piles feature Larssen interlocks
in accordance with EN 10248. AZ, AU, PU and PU-R can be
interlocked together.
The theoretical interlock swing of ArcelorMittal’s Larssen
interlock is 5°.
1.8 Handling holes
Sheet pile sections are normally supplied without handling holes.
If requested, they can be provided as illustrated below on the
centreline of the section.
Table 1.8
Dia
Y
50mm
200mm
50mm
250mm
40mm
75mm
40mm
150mm
40mm
300mm
2 / in
9 in
12
(Dia = 63.5mm; Y = 230mm)
Fig 1.8
Z Sections
Y
U Sections
Y
Straight Web Sections
Y
HZ Sections
Y
Chapter 1/5
Piling Handbook, 8th edition (revised 2008)
Product information
1.9 Plating to increase section modulus
When increased section modulus or inertia is required to cater for
high bending moments over part of the pile length, it may be
economic to attach appropriately sized plates to the pans of the
piles to locally enhance the engineering properties of the section.
It is generally economic to consider this option rather than just
selecting a larger pile section when the pile is very long or when
the pile is at the top of the range anyway.
1.10 Plating to enhance durability
Plates can be attached to Z and U piles to provide increased
durability to parts of the pile where corrosion activity may be high.
This may be the case where the piles are to be installed in a
facility where increased corrosion is expected. The economics of
providing additional sacrificial steel instead of a heavier pile
section will depend upon individual conditions but when the high
corrosion effect is only expected over a short length of the pile,
the plating option will very often prove to be the more cost
effective solution.
1.11 Corners and junctions
The diagram below illustrates the comprehensive range of hot
rolled special sections that is available for use with ArcelorMittal
hot rolled sheet piles to create corners and junctions (except for
GU sections). The special section is attached to the main sheet
pile by welding in accordance with EN12063 and is set back from
the top of the pile by 200mm to facilitate driving.
Corner profiles can also be formed by
• bending single rolled sections for changes in direction up to 25°;
• combining two single bent piles for angles up to 50°;
• cutting the piles and welding them together in the required
orientation.
A comprehensive range of junction piles can be formed by
welding a C9 hot rolled section onto the main sheet pile at the
appropriate location and angle.
One advantage that the special connector has over the more
traditional fabricated corner or junction section is that once a
fabricated pile is formed it cannot easily be changed. In the case
of temporary works, the rolled corners or junctions can be
tacked in place before driving and burned off after extraction to
leave a serviceable pile section and a junction or corner for use
elsewhere. In the case of the Omega 18 and Delta 13 profiles,
the angle is variable and enables corners to be formed at angles
other than 90°.
Chapter 1/6
Piling Handbook, 8th edition (revised 2008)
Product information
Fig 1.11a
-
C 14
Mass ~ 14.4 kg/m
C9
Mass ~ 9.3 kg/m
DELTA 13
Mass ~ 13.1 kg/m
-
OMEGA 18
Mass ~ 18.0 kg/m
Fig 1.11b
2071
2051
2158
2151
2061
Technical assistance is available on request to ascertain what is
required for a particular project.
Drawings of the various rolled profiles may be downloaded from
the following website www.arcelormittal.com/sheetpiling.
Please note that:
- generally bent corners will be supplied as single piles.
- corner sections (C9, C14, Delta13, Omerga18) are not
compatible with GU sections. Contact our technical department
for alternative solutions.
Chapter 1/7
Piling Handbook, 8th edition (revised 2008)
Product information
1.12 Stacking of sheet piles
Fig 1.12
When stacking piles on site it is recommended that they are
placed on timber or steel spacers – to allow straps or chains to be
placed around the bundles – and on a level surface to prevent the
piles being distorted. The spacers should be placed at regular
intervals up to 4m apart along the length of the piles and it is
recommended that the overhang is limited to 1.5m. It is
recommended that pile bundles are stacked not more than 4 high
to prevent excessive loads on the bottom tier.
Bundles should ideally be staggered in plan - as illustrated above
– to provide stability.
Chapter 1/8
Piling Handbook, 8th edition (revised 2008)
Product information
1.13 Z profile piles
1.13.1 Dimensions and properties
t
s
h
b
b
Table 1.13.1a
AZ 12
AZ 13
AZ 13 10/10
AZ 14
AZ 17
AZ 18
AZ 18 10/10
AZ 19
AZ 25
AZ 26
AZ 28
AZ 46
AZ 48
AZ 50
Width
Height
Thickness
b
mm
h
mm
t
mm
s
mm
670
670
670
670
630
630
630
630
630
630
630
580
580
580
302
303
304
304
379
380
381
381
426
427
428
481
482
483
8.5
9.5
10.0
10.5
8.5
9.5
10.0
10.5
12.0
13.0
14.0
18.0
19.0
20.0
8.5
9.5
10.0
10.5
8.5
9.5
10.0
10.5
11.2
12.2
13.2
14.0
15.0
16.0
Sectional
area
Mass
Moment Elastic
Static
Plastic
of inertia section moment section
modulus
modulus
kg/m of kg/m2
cm2/m single pile of wall cm4/m
126
137
143
149
138
150
157
164
185
198
211
291
307
322
66.1
72.0
75.2
78.3
68.4
74.4
77.8
81.0
91.5
97.8
104.4
132.6
139.6
146.7
99 18140
107 19700
112 20480
117 21300
109 31580
118 34200
123 35540
129 36980
145 52250
155 55510
166 58940
229 110450
241 115670
253 121060
Class*
cm3/m
cm3/m
cm3/m
S 240 GP
S 270 GP
S 320 GP
S 355 GP
S 390 GP
S 430 GP
S 460 AP
Section
1200
1300
1350
1400
1665
1800
1870
1940
2455
2600
2755
4595
4800
5015
705
765
795
825
970
1050
1095
1140
1435
1530
1625
2650
2775
2910
1409
1528
1589
1651
1944
2104
2189
2275
2873
3059
3252
5295
5553
5816
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
2
2
3
2
2
2
2
2
2
2
2
2
3
3
2
2
3
3
2
2
2
2
2
2
2
2
3
3
3
2
3
3
3
2
2
2
2
2
2
2
3
3
3
3
3
3
3
3
2
2
2
2
2
2
AZ-700 and AZ-770
AZ 12-770
770 344
8.5
8.5
120
72.6
94 21430 1245
740
1480 2 2 3 3 3 3
AZ 13-770
770 344
9.0
9.0
126
76.1
99 22360 1300
775
1546 2 2 3 3 3 3
AZ 14-770
770 345
9.5
9.5
132
79.5
103 23300 1355
805
1611 2 2 2 2 3 3
AZ 14-770 10/10 770 345 10.0
10.0
137
82.9
108 24240 1405
840
1677 2 2 2 2 2 3
AZ 17-700
700 420
8.5
8.5
133
73.1
104 36230 1730
1015
2027 2 2 3 3 3 3
AZ 18-700
700 420
9.0
9.0
139
76.5
109 37800 1800
1060
2116 2 2 3 3 3 3
AZ 19-700
700 421
9.5
9.5
146
80.0
114 39380 1870
1105
2206 2 2 2 3 3 3
AZ 20-700
700 421 10.0
10.0
152
83.5
119 40960 1945
1150
2296 2 2 2 2 2 3
AZ 24-700
700 459 11.2
11.2
174
95.7
137 55820 2430
1435
2867 2 2 2 2 2 2
AZ 26-700
700 460 12.2
12.2
187
102.9
147 59720 2600
1535
3070 2 2 2 2 2 2
AZ 28-700
700 461 13.2
13.2
200
110.0
157 63620 2760
1635
3273 2 2 2 2 2 2
AZ 37-700
700 499 17.0
12.2
226
124.2
177 92400 3705
2130
4260 2 2 2 2 2 2
AZ 39-700
700 500 18.0
13.2
240
131.9
188 97500 3900
2250
4500 2 2 2 2 2 2
AZ 41-700
700 501 19.0
14.2
254
139.5
199 102610 4095
2370
4745 2 2 2 2 2 2
*: Classification according to EN 1993-5.
Class 1 is obtained by verification of the rotation capacity for a class-2 cross-section.
A set of tables with all the data required for design in accordance with EN 1993-5 is available from our Technical Department.
3
3
3
3
3
3
3
3
2
2
2
2
2
2
3
3
3
3
3
3
3
3
3
2
2
2
2
2
Chapter 1/9
Piling Handbook, 8th edition (revised 2008)
Product information
Z profile piles - Dimensions and properties
Table 1.13.1b
Section
S = Single pile Sectional
D = Double pile
area
cm2
Mass
kg/m
Moment Elastic Radius of Coating
of inertia section gyration area*
modulus
cm4
cm3
cm
m2/m
AZ 12
302
y
303
y
304
y
379
45.4°
y
380
y
8.5
y
381
8.5
y
~360
1340
Per S
Per D
Per m of wall
84.2
168.4
125.7
66.1
132.2
98.7
12160
24320
18140
805
1610
1200
12.02
12.02
12.02
0.83
1.65
1.23
Per S
Per D
Per m of wall
91.7
183.4
136.9
72.0
144.0
107.5
13200
26400
19700
870
1740
1300
11.99
11.99
11.99
0.83
1.65
1.23
Per S
Per D
Per m of wall
99.7
199.4
148.9
78.3
156.6
116.9
14270
28540
21300
940
1880
1400
11.96
11.96
11.96
0.83
1.65
1.23
Per S
Per D
Per m of wall
87.1
174.2
138.3
68.4
136.8
108.6
19900
39800
31580
1050
2100
1665
15.12
15.12
15.12
0.86
1.71
1.35
Per S
Per D
Per m of wall
94.8
189.6
150.4
74.4
148.8
118.1
21540
43080
34200
1135
2270
1800
15.07
15.07
15.07
0.86
1.71
1.35
Per S
Per D
Per m of wall
103.2
206.4
163.8
81.0
162.0
128.6
23300
46600
36980
1225
2445
1940
15.03
15.03
15.03
0.86
1.71
1.35
AZ 13
9.5
y
45.4°
9.5
~360
1340
AZ 14
10.5
y
45.4°
10.5
~360
1340
AZ 17
8.5
8.5
y
~348
55.4°
1260
AZ 18
9.5
9.5
y
~348
55.4°
1260
AZ 19
10.5
10.5
y
55.4°
~348
1260
* One side, excluding inside of interlocks.
Chapter 1/10
Piling Handbook, 8th edition (revised 2008)
Product information
Z profile piles - Dimensions and properties
Table 1.13.1c
Section
S = Single pile
D = Double pile
Sectional
area
Mass
Moment Elastic
of inertia section
modulus
cm4
cm3
Radius of Coating
gyration
area*
cm2
kg/m
Per S
Per D
Per m of wall
116.6
233.2
185.0
91.5
183.0
145.2
32910
65820
52250
1545
3090
2455
16.80
16.80
16.80
0.90
1.78
1.41
Per S
Per D
Per m of wall
124.6
249.2
197.80
97.8
195.6
155.2
34970
69940
55510
1640
3280
2600
16.75
16.75
16.75
0.90
1.78
1.41
Per S
Per D
Per m of wall
133.0
266.0
211.1
104.4
208.8
165.7
37130
74260
58940
1735
3470
2755
16.71
16.71
16.71
0.90
1.78
1.41
Per S
Per D
Per m of wall
168.9
337.8
291.2
132.6
265.2
228.6
64060
128120
110450
2665
5330
4595
19.48
19.48
19.48
0.95
1.89
1.63
Per S
Per D
Per m of wall
177.8
355.6
306.5
139.6
279.2
240.6
67090
134180
115670
2785
5570
4800
19.43
19.43
19.43
0.95
1.89
1.63
Per S
Per D
Per m of wall
186.9
373.8
322.2
146.7
293.4
252.9
70215
140430
121060
2910
5815
5015
19.38
19.38
19.38
0.95
1.89
1.63
cm
m2/m
12.0
AZ 25
~347
58.5°
426
11.2
y
y
1260
13.0
AZ 26
~347
58.5°
427
y
y
428
12.2
y
1260
14.0
AZ 28
13.2
y
~347
58.5°
1260
18.0
AZ 46
481
~387
71.5°
y
482
y
y
483
14.0
y
1160
19.0
AZ 48
15.0
y
~387
71.5°
1160
20.0
AZ 50
16.0
y
71.5°
~387
1160
* One side, excluding inside of interlocks.
Chapter 1/11
Piling Handbook, 8th edition (revised 2008)
Product information
Z profile piles - Dimensions and properties
Table 1.13.1d
Section
S = Single pile
D = Double pile
Sectional
area
Mass
Moment
of inertia
Elastic Radius of Coating
section gyration
area*
modulus
3
cm
cm
m2/m
cm2
kg/m
cm4
Per S
Per D
Per m of wall
95.8
191.6
143.0
75.2
150.4
112.2
13720
27440
20480
905
1810
1350
11.97
11.97
11.97
0.83
1.65
1.23
Per S
Per D
Per m of wall
99.1
198.1
157.2
77.8
155.5
123.4
22390
44790
35540
1175
2355
1870
15.04
15.04
15.04
0.86
1.71
1.35
Per S
Per D
Per m of wall
92.5
185.0
120.1
72.6
145.2
94.3
16500
33000
21430
960
1920
1245
13.36
13.36
13.36
0.93
1.85
1.20
Per S
Per D
Per m of wall
96.9
193.8
125.8
76.1
152.1
98.8
17220
34440
22360
1000
2000
1300
13.33
13.33
13.33
0.93
1.85
1.20
Per S
Per D
Per m of wall
101.3
202.6
131.5
79.5
159.0
103.2
17940
35890
23300
1040
2085
1355
13.31
13.31
13.31
0.93
1.85
1.20
Per S
Per D
Per m of wall
105.6
211.2
137.2
82.9
165.8
107.7
18670
37330
24240
1085
2165
1405
13.30
13.30
13.30
0.93
1.85
1.20
AZ 13 10/10
45.4°
303.5
y
10.0
y
380.5
10.0
y
~360
1340
AZ 18 10/10
10.0
10.0
y
55.4°
~348
1260
AZ 12-770
343.5
~346
y
344.0
39.5°
y
344.5
y
y
345
8.5
8.5
y
1540
AZ 13-770
9.0
9.0
y
39.5°
~346
1540
AZ 14-770
9.5
y
39.5°
9.5
~346
1540
AZ 14-770-10/10
10.0
y
39.5°
10.0
~346
1540
* One side, excluding inside of interlocks.
Chapter 1/12
Piling Handbook, 8th edition (revised 2008)
Product information
Z profile piles - Dimensions and properties
Table 1.13.1e
Section
S = Single pile
D = Double pile
AZ 17 - 700
Sectional
area
Mass
Moment
of inertia
cm2
kg/m
cm4
Elastic Radius of Coating
section gyration
area*
modulus
cm3
cm
m2/m
8.5
419.5
y
420
~346
51.2°
y
420.5
y
y
421
8.5
y
1400
AZ 18 - 700
Per S
Per D
Per m of wall
93.1
186.2
133.0
73.1
146.2
104.4
25360
50720
36230
1210
2420
1730
16.50
16.50
16.50
0.93
1.86
1.33
Per S
Per D
Per m of wall
97.5
194.9
139.2
76.5
153.0
109.3
26460
52920
37800
1260
2520
1800
16.50
16.50
16.50
0.93
1.86
1.33
Per S
Per D
Per m of wall
101.9
203.8
145.6
80.0
160.0
114.3
27560
55130
39380
1310
2620
1870
16.50
16.50
16.50
0.93
1.86
1.33
Per S
Per D
Per m of wall
106.4
212.8
152.0
83.5
167.0
119.3
28670
57340
40960
1360
2725
1945
16.40
16.40
16.40
0.93
1.86
1.33
9.0
9.0
y
~346
51.2°
1400
AZ 19 - 700
9.5
9.5
y
~346
51.2°
1400
AZ 20 - 700
10.0
10.0
y
51.2°
~346
1400
* One side, excluding inside of interlocks.
Chapter 1/13
Piling Handbook, 8th edition (revised 2008)
Product information
Z profile piles - Dimensions and properties
Table 1.13.1f
Section
S = Single pile
D = Double pile
AZ 24-700
Sectional
area
Mass
Moment
of inertia
Elastic Radius of Coating
section gyration
area*
modulus
3
cm
cm
m2/m
cm2
kg/m
cm4
Per S
Per D
Per m of wall
121.9
243.8
174.1
95.7
191.4
136.7
39080
78150
55820
1700
3405
2430
17.90
17.90
17.90
0.97
1.93
1.38
Per S
Per D
Per m of wall
131.0
262.1
187.2
102.9
205.7
146.9
41800
83610
59720
1815
3635
2600
17.86
17.86
17.86
0.97
1.93
1.38
Per S
Per D
Per m of wall
140.2
280.3
200.2
110.0
220.1
157.2
44530
89070
63620
1930
3865
2760
17.83
17.83
17.83
0.97
1.93
1.38
Per S
Per D
Per m of wall
158.2
316.4
226.0
124.2
248.4
177.4
64680
129350
92400
2590
5185
3705
20.22
20.22
20.22
1.03
2.04
1.46
Per S
Per D
Per m of wall
168.0
336.0
240.0
131.9
263.7
188.4
68250
136500
97500
2730
5460
3900
20.16
20.16
20.16
1.03
2.04
1.46
Per S
Per D
Per m of wall
177.8
355.5
254.0
139.5
279.1
199.4
71830
143650
102610
2865
5735
4095
20.10
20.10
20.10
1.03
2.04
1.46
11.2
459
y
460
~361
55.2°
y
461
11.2
y
y
1400
12.2
AZ 26-700
12.2
y
~361
55.2°
1400
AZ 28-700
13.2
13.2
y
~361
55.2°
1400
y
~426
63.2°
499
17.0
y
500
13.3
12.2
y
501
AZ 37-700
y
13.3
1400
AZ 39-700
14.3
18.0
13.2
y
~426
63.2°
14.3
1400
AZ 41-700
15.3
19.0
14.2
y
~426
63.2°
15.3
1400
* One side, excluding inside of interlocks.
Chapter 1/14
Piling Handbook, 8th edition (revised 2008)
Product information
1.13.2 Interlocking in pairs
AZ piles are normally supplied in pairs which saves time in
handling and pitching. They can however, be supplied singly by
prior arrangement but the purchaser must be warned that the
bending strength of single AZ piles, especially the lighter ones, is
very low and damage by plastic deformation under self-weight
can easily occur during handling and driving.
1.13.3 Crimping and welding of the interlocks
Crimping or welding of AZ piles is not necessary to guarantee the
strength of the piled wall, but can be of benefit during handling
and driving.
Fig 1.13.3
AZ-Section
Standard
Crimping
Pile length ≥ 6.0m
6 crimping points every 3,6 m = 1,7 points/m
700
100 100
100 100
100 100
2900
3600
100 100
1800
Crimping
points
1800
3600
700
100 100
100 100
1800
Crimping
points
< 500
3 crimping points every 1,80 m = 1,7 points/m
< 500
Pile length < 6.0m
AZ-Section Standard
Crimping
Chapter 1/15
Piling Handbook, 8th edition (revised 2008)
Product information
1.13.4 Pile form
Piles can be supplied as illustrated.
Fig 1.13.4
Single pile
Pos. A
Pos. B
Double pile
Form I standard
Double
pile
Form II on request
If no particular preference is specified at the time of order, double
piles will be supplied as Form 1.
1.13.5 Circular construction
Steel sheet piling can be driven to form a complete circle without
the need for corner piles. AZ piles have a maximum angle of
deviation of 5°.
The following table gives the approximate minimum diameters of
circular cofferdam which can be constructed using various sheet
pile sections. The diameters are only intended to be for guidance
as the actual interlock deviation achieved will be a function of the
pile length, the pile section, the penetration required. Smaller
diameters can be achieved by introducing bent corner piles, but
larger diameters will result if pairs of piles that have been crimped
or welded are used.
Table 1.13.5
Section
AZ 12, AZ 13, AZ 13/10/10, AZ 14
AZ 17, AZ 18, AZ 18/10/10, AZ 19
AZ 25, AZ 26, AZ 28
AZ 46, AZ 48, AZ 50
AZ 12-770, AZ 13-770,
AZ 14-770, AZ 14-770-10/10
AZ 17-700, AZ 18-700, AZ 19-700,
AZ 20-700
AZ 24-700, AZ 26-700, AZ 28-700
AZ 37-700, AZ 39-700, AZ 41-700
Minimum Approx. min diameter to
number of
internal face of wall
single piles
used
Angle = 5°
m
72
15.1
72
14.1
72
14.0
72
12.8
72
17.3
72
72
72
15.6
15.6
15.5
Contact our technical representatives to obtain data for situations
where plated box piles, double box piles or HZ systems are to be used.
Chapter 1/16
Piling Handbook, 8th edition (revised 2008)
Product information
1.14 U profile piles
1.14.1 Dimensions and properties
Table 1.14.1a
Width Height
Thickness
Sectional
area
b
mm
h
mm
t
mm
s
mm
cm2/m
AU sections
AU 14
AU 16
AU 17
AU 18
AU 20
AU 21
AU 23
AU 25
AU 26
750
750
750
750
750
750
750
750
750
408
411
412
441
444
445
447
450
451
10.0
11.5
12.0
10.5
12.0
12.5
13.0
14.5
15.0
8.3
9.3
9.7
9.1
10.0
10.3
9.5
10.2
10.5
132
147
151
150
165
169
173
188
192
PU sections
PU 12
PU 12 10/10
PU 18 - 1.0
PU 18
PU 22 - 1.0
PU 22
PU 28 - 1.0
PU 28
PU 32
600
600
600
600
600
600
600
600
600
360
360
430
430
450
450
452
454
452
9.8
10.0
10.2
11.2
11.1
12.1
14.2
15.2
19.5
9.0
10.0
8.4
9.0
9.0
9.5
9.7
10.1
11.0
140
148
154
163
174
183
207
216
242
Mass
kg/m of
single pile
Moment Elastic
Static
Plastic
of inertia section moment section
modulus
modulus
kg/m2
of wall
cm4/m
cm3/m
77.9
86.3
89.0
88.5
96.9
99.7
102.1
110.4
113.2
104
115
119
118
129
133
136
147
151
28680
32850
34270
39300
44440
46180
50700
56240
58140
66.1
69.6
72.6
76.9
81.9
86.1
97.4
101.8
114.1
110
116
121
128
137
144
162
170
190
21600
22580
35950
38650
46380
49460
60580
64460
72320
Class*
S 240 GP
S 270 GP
S 320 GP
S 355 GP
S 390 GP
S 430 GP
S 460 AP
Section
cm3/m
cm3/m
1405
1600
1665
1780
2000
2075
2270
2500
2580
820
935
975
1030
1155
1200
1285
1420
1465
1663
1891
1968
2082
2339
2423
2600
2866
2955
2
2
2
2
2
2
2
2
2
2
2
2
3
2
2
2
2
2
3
2
2
3
2
2
2
2
2
3
2
2
3
3
2
3
2
2
3
2
2
3
3
3
3
2
2
3
3
2
3
3
3
3
3
2
3
3
3
3
3
3
3
3
3
1200
1255
1670
1800
2060
2200
2680
2840
3200
715
755
980
1055
1195
1275
1525
1620
1825
1457
1535
1988
2134
2422
2580
3087
3269
3687
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
2
2
2
2
2
3
2
3
2
2
2
2
2
2
The moment of inertia and section moduli values given assume correct shear transfer across the interlock.
*: Classification according to EN 1993-5.
Class 1 is obtained by verification of the rotation capacity for a class 2 cross-section.
A set of tables with all the data required for design in accordance with EN 1993-5 is available from our Technical
Department.
Chapter 1/17
Piling Handbook, 8th edition (revised 2008)
Product information
U profile piles - Dimensions and properties
Table 1.14.1a continued
Width Height
Thickness
Sectional
area
b
mm
h
mm
t
mm
s
mm
PU-R sections
PU 8R
600
PU 9R
600
PU 10R
600
PU 11R
600
PU 13R
675
PU 14R
675
PU 15R
675
280
360
360
360
400
400
400
7.5
7.0
8.0
9.0
10.0
11.0
12.0
6.9
6.4
7.0
7.6
7.4
8.0
8.6
103
105
114
123
124
133
142
GU sections
GU 7-600
GU 8-600
GU 9-600
GU 12-500
GU 13-500
GU 15-500
GU 16-400
GU 18-400
309
309
309
340
340
340
290
292
7.5
8.5
9.5
9.0
10.0
12.0
12.7
15.0
6.4
7.1
7.9
8.5
9.0
10.0
9.4
9.7
100
110
121
144
155
177
197
221
600
600
600
500
500
500
400
400
cm2/m
Mass
kg/m of
single pile
Moment Elastic
Static
Plastic
of inertia section moment section
modulus
modulus
kg/m2
of wall
cm4/m
cm3/m
48.7
49.5
53.8
58.1
65.6
70.5
75.4
81
82
90
97
97
104
112
10830
16930
18960
20960
25690
28000
30290
47.0
51.8
57.0
56.6
60.8
69.3
62.0
69.3
78
86
95
113
122
139
155
173
11350
12690
14060
19640
21390
24810
22580
26090
Class*
S 240 GP
S 270 GP
S 320 GP
S 355 GP
S 390 GP
S 430 GP
S 460 AP
Section
cm3/m
cm3/m
775
940
1055
1165
1285
1400
1515
445
545
610
675
750
815
885
905
1115
1245
1370
1515
1655
1790
3
3
3
2
2
2
2
3
3
3
2
2
2
2
4
4
3
3
2
2
2
4
4
3
3
2
2
2
4
4
3
3
3
2
2
4
4
4
3
3
2
2
-
735
820
910
1155
1260
1460
1560
1785
435
485
540
680
740
855
885
1015
890
995
1105
1390
1515
1755
1815
2080
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
2
3
2
2
2
2
2
2
2
3
2
2
2
2
2
2
2
-
-
-
The moment of inertia and section moduli values given assume correct shear transfer across the interlock.
*: Classification according to EN 1993-5.
Class 1 is obtained by verification of the rotation capacity for a class 2 cross-section.
A set of tables with all the data required for design in accordance with EN 1993-5 is available from our Technical
Department.
Chapter 1/18
Piling Handbook, 8th edition (revised 2008)
Product information
U profile piles - Dimensions and properties
Table 1.14.1b
Section
S = Single pile
D = Double pile
T = Triple pile
AU 14
y'
122.6
408
~303
y
y''
40.9
1500
AU 16
47.8° 11.5
9.3
y'
~303
y'
126.3
411
y
y''
y
42.1
y''
1500
y'
y'
127.4
412
~303
y
42.5
y''
1500
54.7° 10.5
AU 18
~336
441
y'
y
y''
y'
y
y''
1500
54.7° 12.0
~336
444
y'
y'
y
y''
1500
54.7° 12.5
~336
445
y'
140.5
y'
y
y''
1500
59.6° 13.0
y'
~374
y'
y
49.0
y''
1500
AU 25
59.6° 14.5
y'
S
D
T
m of wall
99.2
198.5
297.7
132.3
77.9
155.8
233.7
103.8
6590
43020
59550
28680
457
2110
2435
1405
8.15
14.73
14.15
14.73
0.96
1.91
2.86
1.27
Per
Per
Per
Per
S
D
T
m of wall
109.9
219.7
329.6
146.5
86.3
172.5
258.7
115.0
7110
49280
68080
32850
481
2400
2750
1600
8.04
14.98
14.37
14.98
0.96
1.91
2.86
1.27
Per
Per
Per
Per
S
D
T
m of wall
113.4
226.9
340.3
151.2
89.0
178.1
267.2
118.7
7270
51400
70960
34270
488
2495
2855
1665
8.01
15.05
14.44
15.05
0.96
1.91
2.86
1.27
Per
Per
Per
Per
S
D
T
m of wall
112.7
225.5
338.2
150.3
88.5
177.0
265.5
118.0
8760
58950
81520
39300
554
2670
3065
1780
8.82
16.17
15.53
16.17
1.01
2.00
2.99
1.33
Per
Per
Per
Per
S
D
T
m of wall
123.4
246.9
370.3
164.6
96.9
193.8
290.7
129.2
9380
66660
92010
44440
579
3000
3425
2000
8.72
16.43
15.76
16.43
1.01
2.00
2.99
1.33
Per
Per
Per
Per
S
D
T
m of wall
127.0
253.9
380.9
169.3
99.7
199.3
299.0
132.9
9580
69270
95560
46180
588
3110
3545
2075
8.69
16.52
15.84
16.52
1.01
2.00
2.99
1.33
~374
y'
y
50.1
y''
1500
AU 26
59.6° 15.0
451
y'
y
~374
Per S
130.1
102.1
9830
579
8.69
1.03
Per D
260.1
204.2
76050
3405
17.10
2.04
Per T
390.2
306.3
104680
3840
16.38
3.05
Per m of wall
173.4
136.1
50700
2270
17.10
1.36
Per S
140.6
110.4
10390
601
8.60
1.03
Per D
281.3
220.8
84370
3750
17.32
2.04
Per T
422.0
331.3
115950
4215
16.58
3.05
Per m of wall
187.5
147.2
56240
2500
17.32
1.36
Per S
144.2
113.2
10580
608
8.57
1.03
Per D
288.4
226.4
87220
3870
17.39
2.04
Per T
432.6
339.6
119810
4340
16.64
3.05
Per m of wall
192.2
150.9
58140
2580
17.39
1.36
10.2
150.3
450
y
y''
Per
Per
Per
Per
9.5
147.1
447
y
y''
cm4
10.3
46.8
AU 23
y''
kg/m
10.0
139.3
46.4
AU 21
y
y''
cm2
Elastic Radius of Coating
section gyration
area*
modulus
cm3
cm
m2/m
9.1
135.3
45.1
AU 20
y
y''
Moment
of inertia
47.8° 12.0
9.7
AU 17
y
y''
Mass
47.8° 10.0
8.3
y'
y
y''
Sectional
area
10.5
y'
151.3
50.4
1500
– S: considered neutral axis y'-y'
– D, wall: considered neutral axis y-y
– T: considered neutral axis y"-y"
y
y''
* One side, excluding inside of interlocks.
Chapter 1/19
Piling Handbook, 8th edition (revised 2008)
Product information
U profile piles - Dimensions and properties
Table 1.14.1c
Section
S = Single pile
D = Double pile
T = Triple pile
50.4° 9.8
PU 12
360
y
y''
y'
~258
100.2
9.0
y'
y
33.4
y''
1200
50.4°
PU 12 10/10
y
~256
360
y''
y'
100.4
10.0
10.0
y'
y
33.5
y''
1200
57.5° 10.2
PU 18-1
y'
y
~269
430
y''
8.4
y'
125.6
y y''
41.9
1200
57.5° 11.2
PU 18
y'
y
~269
430
y''
9.0
y'
127.6
y y''
42.5
1200
62.4° 11.1
PU 22-1
y'
~297
450
y
y''
9.0
y'
136.2
y y''
45.4
1200
62.4° 12.1
PU 22
y'
y
~297
450
y''
9.5
y'
138.1
y y''
46.0
1200
Mass
Moment
of inertia
cm2
kg/m
cm4
Elastic Radius of
section gyration
modulus
cm3
cm
Coating
area*
m2/m
Per
Per
Per
Per
S
D
T
m of wall
84.2
168.4
252.6
140.0
66.1
132.2
198.3
110.1
4500
25920
36060
21600
370
1440
1690
1200
7.31
12.41
11.95
12.41
0.80
1.59
2.38
1.32
Per
Per
Per
Per
S
D
T
m of wall
88.7
177.3
266.0
147.8
69.6
139.2
208.8
116.0
4600
27100
37670
22580
377
1505
1765
1255
7.20
12.36
11.90
12.36
0.80
1.59
2.38
1.32
Per
Per
Per
Per
S
D
T
m of wall
92.5
185.0
277.5
154.2
72.6
145.2
217.8
121.0
6960
43140
59840
35950
473
2005
2330
1670
8.67
15.3
14.69
15.3
0.87
1.72
2.58
1.43
Per
Per
Per
Per
S
D
T
m of wall
98.0
196.0
294.0
163.3
76.9
153.8
230.7
128.2
7220
46380
64240
38650
484
2160
2495
1800
8.58
15.38
14.78
15.38
0.87
1.72
2.58
1.43
Per
Per
Per
Per
S
D
T
m of wall
104.3
208.7
313.0
173.9
81.9
163.8
245.7
136.5
8460
55650
77020
46380
535
2475
2850
2060
9.01
16.33
15.69
16.33
0.90
1.79
2.68
1.49
Per
Per
Per
Per
S
D
T
m of wall
109.7
219.5
329.2
182.9
86.1
172.3
258.4
143.6
8740
59360
82060
49460
546
2640
3025
2200
8.93
16.45
15.79
16.45
0.90
1.79
2.68
1.49
Per
Per
Per
Per
S
D
T
m of wall
124.1
248.2
372.3
206.8
9740
72700
100170
60580
576
3215
3645
2680
8.86
17.12
16.40
17.12
0.93
1.85
2.77
1.54
68.0° 14.2
PU 28-1.0
9.7
y'
y
~339
452
y'
y''
Sectional
area
146.4
y
48.8
1200
– S: considered neutral axis y'-y'
– D, wall: considered neutral axis y-y
– T: considered neutral axis y"-y"
Chapter 1/20
y''
97.4
194.8
292.2
162.3
* One side, excluding inside of interlocks.
Piling Handbook, 8th edition (revised 2008)
Product information
U profile piles - Dimensions and properties
Table 1.14.1c continued
Section
S = Single pile
D = Double pile
T = Triple pile
10.1
y'
y'
~339
148.5
454
y
y
49.5
y''
1200
68.1° 19.5
PU 32
y'
y
~342
149.4
452
y''
Mass
Moment
of inertia
cm2
kg/m
cm4
Elastic Radius of Coating
section gyration
area*
modulus
cm3
cm
m2/m
68.0° 15.2
PU 28
y''
Sectional
area
11.0
y'
y
49.8
y''
1200
Per
Per
Per
Per
S
D
T
m of wall
129.7
259.4
389.0
216.1
101.8
203.6
305.4
169.6
10070
77350
106490
64460
589
3405
3850
2840
8.81
17.27
16.55
17.27
0.93
1.85
2.77
1.54
Per
Per
Per
Per
S
D
T
m of wall
145.4
290.8
436.2
242.0
114.1
228.3
342.4
190.2
10950
86790
119370
72320
633
3840
4330
3200
8.68
17.28
16.54
17.28
0.92
1.83
2.74
1.52
Sectional
area
Mass
Moment
of inertia
cm2
kg/m
cm4
Table 1.14.1d
Section
S = Single pile
D = Double pile
T = Triple pile
y''
y
~323
280
PU 8R
49.5° 7.5
6.9
y'
y'
84.5
y
28.2
Per S
PU 9R
y
~296
y'
102.8
y'
y
34.3
y''
1200
PU 10R
y
y'
~296
105.8
y'
y
35.3
y''
1200
PU 11R
200
930
1070
775
5.78
10.24
9.85
10.24
0.76
1.51
2.27
1.26
Per
Per
Per
Per
S
D
T
m of wall
63.0
126.0
189.1
105.0
49.5
98.9
148.4
82.5
3500
20320
28260
16930
285
1130
1320
940
7.45
12.70
12.23
12.70
0.81
1.62
2.42
1.35
Per
Per
Per
Per
S
D
T
m of wall
68.5
137.1
205.6
114.2
53.8
107.6
161.4
89.7
3700
22750
31570
18960
295
1265
1465
1055
7.35
12.88
12.39
12.88
0.81
1.62
2.42
1.35
Per
Per
Per
Per
S
D
T
m of wall
74.1
148.1
222.2
123.4
58.1
116.3
174.4
96.9
3890
25150
34830
20960
305
1395
1610
1165
7.25
13.03
12.52
13.03
0.81
1.62
2.42
1.35
54.5° 9.0
7.6
y
~296
360
y''
2070
13000
18030
10830
54.5° 8.0
7.0
360
y''
48.7
97.3
146.0
81.1
54.5° 7.0
6.4
360
y''
Per T
Per m of wall
62.0
124.0
186.0
103.3
y'' Per D
1200
Elastic Radius of Coating
section gyration
area*
modulus
cm3
cm
m2/m
y'
108.3
y'
y
36.1
1200
– S: considered neutral axis y'-y'
– D, wall: considered neutral axis y-y
– T: considered neutral axis y"-y"
y''
* One side, excluding inside of interlocks.
Chapter 1/21
Piling Handbook, 8th edition (revised 2008)
Product information
U profile piles - Dimensions and properties
Table 1.14.1d continued
Section
S = Single pile
D = Double pile
T = Triple pile
PU 13R
400
y
y''
49.5° 10.0
y'
y
39.9
y''
1350
PU 14R
400
y''
49.5° 11.0
y
y'
8.0
y'
121.5
~300
y
40.5
y''
1350
PU 15R
400
y''
49.5° 12.0
y
y'
~300
123.2
8.6
y'
y
41.1
1350
– S: considered neutral axis y'-y'
– D, wall: considered neutral axis y-y
– T: considered neutral axis y"-y"
Chapter 1/22
Mass
Moment
of inertia
cm2
kg/m
cm4
Elastic Radius of Coating
section gyration
area*
modulus
cm3
cm
m2/m
7.4
y'
119.6
~300
Sectional
area
y''
Per
Per
Per
Per
S
D
T
m of wall
83.6
167.2
250.8
123.8
65.6
131.2
196.9
97.2
5390
34680
48040
25690
385
1735
2005
1285
8.03
14.40
13.84
14.40
0.89
1.78
2.66
1.32
Per
Per
Per
Per
S
D
T
m of wall
89.8
179.7
269.5
133.1
70.5
141.0
211.5
104.5
5630
37800
52280
28000
395
1890
2175
1400
7.92
14.51
13.93
14.51
0.89
1.78
2.66
1.32
Per
Per
Per
Per
S
D
T
m of wall
96.1
192.1
288.2
142.3
75.4
150.8
226.2
111.7
5860
40890
56470
30290
410
2045
2340
1515
7.81
14.59
14.00
14.59
0.89
1.78
2.66
1.32
* One side, excluding inside of interlocks.
Piling Handbook, 8th edition (revised 2008)
Product information
U profile piles - Dimensions and properties
Table 1.14.1e
Section
S = Single pile
D = Double pile
T = Triple pile
GU 7-600
42.5° 7.5 6.4
309
y
y''
y'
y'
85.5
y
y''
28.5
~249
1200
GU 8-600
y
y'
86.6
y
y''
28.9
~249
1200
GU 9-600
42.5° 9.5 7.9
y'
309
y''
y
y'
87.4
y
y''
29.1
~249
1200
GU 12-500
y
y'
92.9
y
31.0
~262
y''
1000
GU 13-500
60.0° 10.0
340
y''
y
y'
93.8
y'
y
y''
1000
60.0° 12.0
10.0
340
y
y'
95.1
y'
y
31.7
~262
y''
1000
GU 16-400
82.1°
290
y''
y
y'
~252
kg/m
cm4
Per
Per
Per
Per
S
D
T
m of wall
59.8
119.7
179.5
99.7
47.0
94.0
140.9
78.3
2440
13620
18980
11350
230
880
1035
735
6.39
10.67
10.28
10.67
0.76
1.51
2.27
1.26
Per
Per
Per
Per
S
D
T
m of wall
66.0
132.0
198.0
110.0
51.8
103.6
155.4
86.4
2670
15230
21190
12690
245
985
1155
820
6.36
10.74
10.35
10.74
0.76
1.51
2.27
1.26
Per
Per
Per
Per
S
D
T
m of wall
72.6
145.2
217.8
121.0
57.0
114.0
170.9
95.0
2900
16880
23470
14060
265
1090
1280
910
6.32
10.78
10.38
10.78
0.76
1.51
2.27
1.26
Per
Per
Per
Per
S
D
T
m of wall
72.1
144.3
216.4
144.3
56.6
113.2
169.9
113.2
3600
19640
27390
19640
315
1155
1365
1155
7.06
11.67
11.25
11.67
0.73
1.44
2.16
1.44
Per
Per
Per
Per
S
D
T
m of wall
77.5
155.0
232.5
155.0
60.8
121.7
182.5
121.7
3870
21390
29810
21390
335
1260
1480
1260
7.07
11.75
11.32
11.75
0.73
1.44
2.16
1.44
Per
Per
Per
Per
S
D
T
m of wall
88.3
176.5
264.8
176.5
69.3
138.6
207.9
138.6
4420
24810
34550
24810
370
1460
1715
1460
7.07
11.86
11.42
11.86
0.73
1.44
2.16
1.44
87.8
Per
Per
Per
Per
S
D
T
m of wall
78.9
157.9
236.8
197.3
62.0
123.9
185.9
154.9
2950
18060
25060
22580
265
1245
1440
1560
6.11
10.70
10.29
10.70
0.65
1.28
1.92
1.60
Per
Per
Per
Per
S
D
T
m of wall
88.3
176.7
265.0
220.8
69.3
138.7
208.0
173.3
3290
20870
28920
26090
290
1430
1645
1785
6.10
10.87
10.45
10.87
0.65
1.28
1.92
1.60
12.7
9.4
y'
y
29.3
y''
800
GU 18-400
82.1°
292
y''
cm2
Elastic Radius of Coating
section gyration
area*
modulus
cm3
cm
m2/m
9.0
31.3
~262
GU 15-500
y''
Moment
of inertia
60.0° 9.0
8.5
y'
340
y''
Mass
42.5° 8.5 7.1
y'
309
y''
Sectional
area
y
y'
~252
90.0
30.0
15.0
9.7
y'
y
y''
800
– S: considered neutral axis y'-y'
– D, wall: considered neutral axis y-y
– T: considered neutral axis y"-y"
* One side, excluding inside of interlocks.
Chapter 1/23
Piling Handbook, 8th edition (revised 2008)
Product information
1.14.2 Interlocking in pairs
U piles are normally supplied as single piles and are easily
handled, stacked and pitched in that form. Subject to prior
arrangement, U piles can be supplied interlocked in pairs to
minimise the number of handling and pitching operations on site.
It should be noted however that when interlocked in pairs, the
resulting shape is asymmetric requiring care when stacking.
When U piles are interlocked prior to delivery in pairs there are
two possible orientations when viewed from the end of the pile
with the lifting hole as illustrated in Fig 1.14.4. The orientation can
be reversed by burning lifting holes at the bottom of the pile and
picking it up using the revised holes.
Development of section modulus
When sheet piles are driven into reasonably competent soils the
longitudinal shear force that develops between the inner and outer
leaves of a pair of U piles as a result of bending is resisted by:
• Friction resulting from the variation of interlock geometry along
the length of a pile
• Friction due to soil particles being forced into the interlocks
during driving
• Embedment of the piles below excavation level to a depth
necessary to create sufficient passive resistance
• Friction at the soil/pile interfaces
• Interaction with walings and capping beams
• The type of the installed sheet pile (single, double, triple)
• The driving method
If the resistance generated by these factors is sufficient to
counteract the longitudinal shear force, the piles will develop full
section modulus.
However, it is advisable, in certain conditions, to connect together
the inner and outer leaves of a wall by crimping or welding the
common interlock to ensure that the necessary resistance to
longitudinal shear is developed. Such conditions arise when:
• The piles are acting in cantilever
• The piles are prevented from penetrating to the design depth of
embedment by rock or hard ground
• The piles are supporting open water or very soft clays and silts;
• The pile interlocks have been lubricated
Chapter 1/24
Piling Handbook, 8th edition (revised 2008)
Product information
U piles have been in use for almost a century for the construction
of embedded retaining walls and the need for caution when
designing walls in the situations mentioned above is understood.
Whilst adoption of the maximum modulus in the situations
mentioned above may be slightly optimistic, the automatic
reduction of the wall modulus developed by U piles to that of the
unconnected sections is far too pessimistic.
1.14.3 Crimping and welding of the interlocks
Pairs of piles can be crimped or welded together if required.
Normally 3 to 4 crimps per metre are requested but other
configurations can be accommodated with prior agreement. Each
crimp is applied to provide an allowable shear resistance of 75kN
with less than 5mm movement.
Fig 1.14.3
PU, PU-R and
GU Sections
Standard
Crimping
6 crimping points every 1,7 m = 3,5 points/m
AU-Section
Standard
Crimping
100 100
100 100
Crimping
points
700
700
100 100
100 100
< 500
< 500
3 crimping points every 0,75 m = 4 points/m
800
Smaller crimping
paths on request.
1000
Smaller crimping
paths on request.
100 100
100 100
700
700
100 100
100 100
1000
800
Crimping
points
1.14.4 Pile form
Piles can be supplied as illustrated.
Fig 1.14.4
Form S standard
Single pile
Form Z on request
Double pile
Triple pile
Chapter 1/25
Piling Handbook, 8th edition (revised 2008)
Product information
1.14.5 Circular construction
Steel sheet piling can be driven to form a complete circle without
the need for corner piles. The maximum angle of deviation for AU,
PU, PU-R and GU sections is 5° for single piles.
The following table gives the approximate minimum diameters of
circular cofferdam which can be constructed using various sheet
pile sections. The diameters are only intended to be for guidance
as the actual interlock deviation achieved will be a function of the
pile length, the pile section, the penetration required. Smaller
diameters can be achieved by introducing bent corner piles, but
larger diameters will result from using pairs of piles that have been
crimped or welded.
Table 1.14.5
Section
Chapter 1/26
Minimum
number of
single piles
used
Angle = 5°
Approx. min diameter to
internal face of wall
AU 14, AU 16, AU 17
72
16.8
AU 18, AU 20, AU 21
72
16.8
AU 23, AU 25, AU 26
72
16.8
PU 12, PU 12 10/10
72
13.4
PU 18, PU 22, PU28, PU 32
72
13.3
PU 8R
72
13.5
PU 9R, PU 10R, PU 11R
72
13.4
PU 13R, PU 14R, PU 15R
72
15.1
GU 7-600, GU 8-600, GU 9-600
72
13.4
GU 12-500, GU 13-500, GU 15-500
72
11.1
GU 16-400, GU 18-400
72
8.9
m
Piling Handbook, 8th edition (revised 2008)
Product information
1.15 Straight web piles
1.15.1 Dimensions and properties for AS-500 Straight Web piles
Fig 1.15.1a
finger
t
δ
thumb
b
~ 92mm
α
Table 1.15.1
Section
AS
AS
AS
AS
AS
500-9,5
500-11,0
500-12,0
500-12,5
500-12,7
Nominal
Web
Deviation PeriSteel
Mass per
width* thickness
angle meter of section
m of a
a single
of a
single
pile
single pile
pile
b
t
δ
mm
mm
°
cm
cm2
kg/m
500
500
500
500
500
9.5
11.0
12.0
12.5
12.7
4.5**
4.5**
4.5**
4.5**
4.5**
138
139
139
139
139
81.3
90.0
94.6
97.2
98.2
63.8
70.6
74.3
76.3
77.1
Mass
per m2
of wall
Moment Section
of inertia modulus
of a single pile
Coating
area***
kg/m2
cm4
cm3
m2/m
128
141
149
153
154
168
186
196
201
204
46
49
51
51
51
0.58
0.58
0.58
0.58
0.58
Note: all straight web sections interlock with each other.
* The effective width to be taken into account for design purposes (lay-out) is 503 mm for all AS 500 sheet piles.
** Max. deviation angle 4.0° for pile length > 20 m.
*** On one side, excluding inside of interlocks.
Chapter 1/27
Piling Handbook, 8th edition (revised 2008)
Product information
Interlock Strength
The interlock complies with EN 10248. Following interlock strength
Fmax can be achieved with a steel grade S 355 GP. However, higher
steel grades are available.
Sheet pile
AS 500 - 9.5
AS 500 - 11.0
AS 500 - 12.0
AS 500 - 12.5
AS 500 - 12.7
Fmax [ kN/m]
3,000
3,500
5,000
5,500
5,500
Junction piles
In general junction piles are assembled by welding in accordance
with EN 12063.
Fig 1.15.1b
2
b_
2
b_
120°
θ
θ
b
_
2
b_
2
b_
2
b_
2
BI
150mm
BP
Y
The connecting angle θ should be in the range from 30° to 45°.
Types of cell
Fig 1.15.1c
Circular cells with 35° junction piles and
one or two connecting arcs.
Diaphragm cells with 120° junction piles.
Bent piles
If deviation angles exceeding the values given in table 1.15.1 have
to be attained, piles pre-bent in the mill may be used.
Fig 1.15.1d
β
CI
Chapter 1/28
β
CP
Piling Handbook, 8th edition (revised 2008)
Product information
1.16 Combined wall systems
1.16.1 HZ/AZ pile system
The HZ /AZ wall is a combined wall system involving HZ king piles
as the main structural support elements, AZ sheet piles as the
infill members with special connectors to join the parts together.
The following tables give dimensions and properties for the
component parts (AZ pile data can be found in Section 1.13.1).
A new combined wall system HZ-M/AZ will be available from
end of 2008 on, based on an innovative concept. During a
transition period, both HZ and HZ-M systems will be
manufactured.
Table 1.16.1a
Section
Dimensions
h
mm
t
HZ
r
h
y
y
b
mm
Sec- Mass Moment
tional
of
area
inertia
t
s
r
y-y
mm mm mm cm2 kg/m
cm4
Elastic
Perisection meter
modulus
y-y
cm3
m2/m
Interlocking
section
HZ 775 A 775.0 460.0 17.0 12.5 20
257.9 202.4 280070
7230
3.39 RH16-RZDU16
HZ 775 B 779.0 460.0 19.0 12.5 20
276.3 216.9 307930
7905
3.40 RH16-RZDU16
HZ 775 C 783.0 461.5 21.0 14.0 20
306.8 240.8 342680
8755
3.41 RH20-RZDU18
HZ 775 D 787.0 461.5 23.0 14.0 20
325.3 255.3 371220
9435
3.42 RH20-RZDU18
HZ 975 A 975.0 460.0 17.0 14.0 20
297.0 233.1 476680
9780
3.79 RH16-RZDU16
HZ 975 B 979.0 460.0 19.0 14.0 20
315.4 247.6 520700
10635
3.79 RH16-RZDU16
HZ 975 C 983.0 462.0 21.0 16.0 20
353.9 277.8 582170
11845
3.81 RH20-RZDU18
HZ 975 D 987.0 462.0 23.0 16.0 20
372.4 292.3 627120
12710
3.81 RH20-RZDU18
s
b
RH
z
y h
y
RH 16
62
68
–
12.2
–
20.4
16.0
83
26
–
–
RH 20
67
79
–
14.2
–
25.5
20.0
123
34
–
–
RZU 16
62
80
–
–
–
20.6
16.1
70
18
–
–
RZU 18
67
84
–
–
–
22.9
17.9
95
23
–
–
RZD 16
62
80
–
–
–
20.6
16.2
58
19
–
–
RZD 18
67
84
–
–
–
22.9
18.1
80
22
–
–
z
b
RZU
z
y h
y
z
b
RZD
z
y
y h
z
b
Chapter 1/29
Piling Handbook, 8th edition (revised 2008)
Product information
The outstanding feature of this form of wall is the range of options
that can be created by combining different beams, sheet piles and
connectors.
For example the combination of a single beam and sheet pile with
connectors to join everything together can be modified by adding
additional ‘connectors’ to the rear flange of the beam at the level
of highest bending moment applied or by adopting two beams for
every pair of sheet piles.
The following tables give an indication of what properties can be
generated for particular combinations of components.
Table 1.16.1b
Section
Combination HZ … -12 / AZ 18
h
y
y
1790
Combination HZ … -24 / AZ 18
h
y
y
2270
* Referring to outside of connector
** Referring to outside of HZ flange
*** Length of RZ connector = Length of AZ
*** Length of RH connector = Length of HZ
Chapter 1/30
Dimension
Properties per metre of wall
h
Sectional
area
Moment
of inertia
Mass***
mm
cm /m
cm /m
HZ 775 A
775.0
273.0
210000
5720
4765
174
214
2.332
HZ 775 B
779.0
283.3
225980
6095
5140
182
222
2.332
HZ 775 C
783.0
303.0
248530
6660
5630
197
238
2.346
HZ 775 D
787.0
313.3
264810
7040
6005
205
246
2.346
HZ 975 A
975.0
294.8
337840
7340
6180
191
231
2.332
HZ 975 B
979.0
305.1
363060
7815
6655
199
240
2.332
HZ 975 C
983.0
329.3
402610
8610
7360
217
258
2.347
HZ 975 D
987.0
339.6
428250
9095
7835
225
267
2.347
HZ 775 A
775.0
346.8
317820
7120
7675
240
272
2.866
HZ 775 B
779.0
363.0
342750
7690
8270
253
285
2.866
HZ 775 C
783.0
396.5
382550
8540
9190
279
311
2.886
HZ 775 D
787.0
412.8
407960
9120
9780
291
324
2.886
HZ 975 A
975.0
381.3
521630
9505
10090
267
299
2.865
HZ 975 B
979.0
397.5
561040
10220
10840
280
312
2.865
HZ 975 C
983.0
438.0
629940
11440
12135
311
344
2.888
HZ 975 D
987.0
454.3
670070
12170
12885
324
357
2.888
2
4
Elastic**
section
l AZ =
modulus 60 % l HZ
3
cm /m
kg/m2
Coating area
Elastic*
section
modulus
cm3/m
l AZ =
l HZ
kg/m2
Waterside
m2/m
Piling Handbook, 8th edition (revised 2008)
Product information
Table 1.16.1c
Section
Dimension
Properties per meter of wall
b
h
Sectional
area
mm
mm
cm /m
Mass
Moment of Elastic* Elastic**
inertia section section
modulus modulus
cm4/m
cm3/m cm3/m
Coating area
kg/m
Waterside
m2/m
HZ 775 A 475.0 775.0
585.8
649450
16595
15615
460
0.534
HZ 775 B 475.0 779.0
624.5
708720
17985
17030
490
0.534
HZ 775 C 479.0 783.0
693.7
789060
20055
18735
545
0.540
HZ 775 D 479.0 787.0
732.3
849160
21470
20140
575
0.540
HZ 975 A 475.0 975.0
668.1
1098910 22515
21185
524
0.534
HZ 975 B 475.0 979.0
706.8
1192510 24280
22970
555
0.534
* Referring to outside of connector HZ 975 C 480.0 983.0
790.4
1330350 27130
25380
620
0.541
** Referring to outside of HZ-flange HZ 975 D 480.0 987.0
828.9
1424880 28915
27155
651
0.541
Combination C1
b
h
Driving Direction
y
1.16.2 Box piles
y
2
2
General
Welded box piles are fabricated from conventional hot rolled sheet
piles and can therefore be supplied in the steel grades indicated
in table 1.3.1 and to the lengths indicated in section 1.6. Where
greater lengths are required or in cases where equipment on site
is unable to handle the total required length, the piles can be
extended with minimal effort using site butt welds. Welding details
are available on request.
Box piles, formed from four AZ sections, a pair of AZ’s and a plate
or a pair of U sections can be conveniently introduced into a line
of sheet piling at any point where heavy loads are to be applied.
They can be used to resist vertical and horizontal forces and can
generally be positioned in the wall such that its appearance is
unaffected.
Boxes may also be used as individual bearing piles for
foundations or in open jetty and dolphin construction. Their large
radius of gyration makes them particularly suitable for situations
where construction involves long lengths of pile with little or no
lateral support.
In general, box piles are driven open ended. Soil displacement
and ground heave is normally eliminated since the soil enters the
open end of the pile during initial penetration and forms an
effective plug as the toe depth increases. Box piles can be driven
into all normal soils, very compact ground and soft rocks.
CAZ box piles
CAZ box piles are formed by welding together two pairs of
interlocked and intermittently welded AZ sheet piles.
Chapter 1/31
Piling Handbook, 8th edition (revised 2008)
Product information
h
b
Table 1.16.2a Dimensions and properties of CAZ box piles
Section
b
h
mm
mm
cm
cm2
cm2
kg/m
y-y
cm4
z-z
cm4
CAZ 12
1340
604
348
293
4166
230
125610
369510
4135
5295
20.7
3.29
CAZ 13
1340
606
349
320
4191
251
136850
402270
4490
5765
20.7
3.29
CAZ 14
1340
608
349
348
4217
273
148770
436260
4865
6255
20.7
3.29
CAZ 17
1260
758
360
305
4900
239
205040
335880
5385
5105
25.9
3.41
CAZ 18
1260
760
361
333
4925
261
222930
365500
5840
5560
25.9
3.41
CAZ 19
1260
762
361
362
4951
284
242210
396600
6330
6035
25.9
3.41
CAZ 25
1260
852
376
411
5540
323
343000
450240
8020
6925
28.9
3.57
CAZ 26
1260
854
377
440
5566
346
366820
480410
8555
7385
28.9
3.57
CAZ 28
1260
856
377
471
5592
370
392170
513050
9125
7820
28.9
3.57
CAZ 46
1160
962
401
595
5831
467
645940
527590
13380
8825
32.9
3.81
CAZ 48
1160
964
402
628
5858
493
681190
556070
14080
9300
32.9
3.81
CAZ 50
1160
966
402
661
5884
519
716620
584560
14780
9780
32.9
3.81
CAZ 12-770
1540
687
389
328
5431
257
175060
557980
3295
4545
23.1
3.67
CAZ 13-770
1540
688
389
344
5446
270
183440
584640
3445
4755
23.1
3.67
CAZ 14-770
1540
689
390
360
5461
283
191840
611290
3600
4985
23.1
3.67
CAZ 14-770-10/1 1540
690
390
376
5476
295
200280
637960
3750
5190
23.1
3.67
CAZ 17 - 700
1400
839
391
330
6015
259
265280
457950
6300
6285
28.3
3.69
CAZ 18 - 700
1400
840
391
347
6029
272
277840
479790
6590
6590
28.3
3.69
CAZ 19 - 700
1400
841
392
363
6044
285
290440
501620
6880
6890
28.3
3.69
CAZ 20 - 700
1400
842
392
379
6058
297
303090
523460
7170
7195
28.3
3.69
CAZ 24 - 700
1400
918
407
436
6616
342
412960
596900
8965
8260
30.8
3.85
CAZ 26 - 700
1400
920
407
469
6645
368
444300
641850
9625
8900
30.8
3.85
CAZ 28 - 700
1400
922
408
503
6674
395
475810
686880
10285
9510
30.8
3.85
CAZ 37 - 700
1400
998
431
556
7223
437
652440
738380
13030 10285
34.2
4.10
CAZ 39 - 700
1400 1000
432
592
7253
465
692730
784530
13805 10930
34.2
4.10
CAZ 41 - 700 1400 1002
432
628
7283
* The mass of welds is not taken into account
** Outside surface, excluding inside of interlocks
493
733230
830690
14585 11570
34.2
4.10
Chapter 1/32
Perim Sectional Total Mass*
Area
Section
Area
Moment of
Inertia
Elastic section Min Coating **
modulus
Rad of area
gyration
y-y
z-z
cm3
cm3
cm
m2/m
Piling Handbook, 8th edition (revised 2008)
Product information
z
y
y
h
z
b
Table 1.16.2b Dimensions and properties of CAU, CU, CPU-R and CGU box piles
Section
b
h
mm
mm
Perim Sectional Total Mass*
Area
Section
Area
cm
cm2
cm2
CAU double box piles
CAU 14 - 2
750 451
230
198
2598
CAU 16 - 2
750 454
231
220
2620
CAU 17 - 2
750 455
231
227
2626
CAU 18 - 2
750 486
239
225
2888
CAU 20 - 2
750 489
240
247
2910
CAU 21 - 2
750 490
240
254
2916
CAU 23 - 2
750 492
244
260
3013
CAU 25 - 2
750 495
245
281
3034
CAU 26 - 2
750 496
245
288
3041
CU double box piles
CU 12 - 2
600 403
198
168
1850
CU 12 10/10 - 2 600 403
198
177
1850
CU 18 - 2
600 473
212
196
2184
CU 22 - 2
600 494
220
219
2347
CU 28 - 2
600 499
226
259
2468
CU 32 - 2
600 499
223
291
2461
CPU-R double box piles
CPU 8R-2
600 318
188
124
1555
CPU 9R-2
600 399
199
126
1893
CPU 10R-2
600 399
199
137
1893
CPU 11R-2
600 399
199
148
1893
CPU 13R-2
675 441
215
167
2275
CPU 14R-2
675 441
215
180
2275
CPU 15R-2
675 441
215
192
2275
* The mass of welds is not taken into account
** Outside surface, excluding inside of interlocks
* The mass of welds is not taken into account
** Outside surface, excluding inside of interlocks
Moment of
Inertia
Elastic section Min Coating **
modulus
Rad of area
gyration
y-y
z-z
cm3
cm3
cm
m2/m
kg/m
y-y
cm4
z-z
cm4
155.8
172.5
178.1
177.0
193.8
199.3
204.2
220.8
226.4
54400
62240
64840
73770
83370
86540
94540
104810
108260
121490
130380
133330
142380
151220
153990
157900
166600
169510
2415
2745
2855
3035
3405
3530
3845
4235
4365
3095
3325
3400
3625
3850
3920
4020
4240
4315
16.6
16.8
16.9
18.1
18.4
18.5
19.1
19.3
19.4
2.04
2.04
2.04
2.14
2.14
2.14
2.19
2.19
2.19
132.2
139.2
153.8
172.3
203.6
228.3
34000
35580
58020
73740
96000
108800
70000
73460
78300
88960
103560
109200
1685
1765
2455
2985
3850
4360
2205
2315
2470
2800
3260
3435
14.2
14.2
17.2
18.3
19.2
19.3
1.72
1.72
1.86
1.94
2.00
1.97
97.3
98.9
107.6
116.3
131.2
141.0
150.8
17380
25850
28930
31970
43580
47510
51400
52200
54900
57700
60490
82570
86610
90640
1095
1295
1450
1600
1975
2155
2330
1655
1740
1825
1915
2335
2450
2560
11.8
14.3
14.5
14.7
16.1
16.3
16.4
1.62
1.73
1.73
1.73
1.89
1.89
1.89
Chapter 1/33
Piling Handbook, 8th edition (revised 2008)
Product information
Table 1.16.2b – continued
Section
b
h
mm
mm
Perim Sectional Total Mass*
Area
Section
Area
cm
cm2
CGU double box piles
CGU 7-600
600 350
184
120
CGU 8-600
600 352
184
132
CGU 9-600
600 354
184
145
CGU 12-500
500 381
178
144
CGU 13-500
500 383
179
155
CGU 15-500
500 387
180
177
CGU 16-400
400 336
169
158
CGU 18-400
400 340
169
177
* The mass of welds is not taken into account
** Outside surface, excluding inside of interlocks
Chapter 1/34
Moment of
Inertia
cm2
kg/m
y-y
cm4
z-z
cm4
1613
1625
1638
1514
1525
1546
1170
1187
94.0
103.6
114.0
113.2
121.7
138.6
123.9
138.7
18320
20760
23330
25800
28420
33750
25270
29520
50470
54520
58990
44790
47370
52570
31900
34560
Elastic section Min Coating **
modulus
Rad of area
gyration
y-y
z-z
cm3
cm3
cm
m2/m
1045
1180
1320
1355
1485
1740
1505
1735
1595
1725
1865
1665
1760
1955
1465
1585
12.4
12.5
12.7
13.4
13.5
13.8
12.7
12.9
1.60
1.60
1.60
1.54
1.54
1.54
1.40
1.40
Piling Handbook, 8th edition (revised 2008)
Product information
z
y
y
h
z
b
Table 1.16.2c Dimensions and properties of CAU, CU and CPU-R box piles
Section
b
h
mm
mm
Perim Sectional Total Mass*
Area Section
Area
cm
cm2
CAU triple box piles
CAU 14 - 3
957
908
341
298
CAU 16 - 3
960
910
342
330
CAU 17 - 3
960
910
343
340
CAU 18 - 3
1009 927
355
338
CAU 20 - 3
1012 928
356
370
CAU 21 - 3
1013 929
359
381
CAU 23 - 3
1036 930
361
390
CAU 25 - 3
1038 931
364
422
CAU 26 - 3
1039 932
364
433
CU triple box piles
CU 12 - 3
800
755
293
253
CU 12 10/10 - 3 800
755
293
266
CU 18 - 3
877
790
315
294
CU 22 - 3
912
801
326
329
CU 28 - 3
938
817
336
389
CU 32 - 3
926
809
331
436
CPU-R triple box piles
CPU 8R-3
757
709
278
186
CPU 9R-3
815
750
295
189
CPU 10R-3
815
750
295
206
CPU 11R-3
815
750
295
222
CPU 13R-3
888
836
319
251
CPU 14R-3
888
836
319
269
CPU 15R-3
888
836
319
288
* The mass of welds is not taken into account
** Outside surface, excluding inside of interlocks
Moment of
Inertia
y-y
cm4
z-z
cm4
Elastic section Min Coating **
modulus Rad of area
gyration
y-y
z-z
cm3
cm3
cm
m2/m
cm2
kg/m
6454
6486
6496
6886
6919
6926
7073
7106
7115
233.7
258.7
267.2
265.5
290.7
299.0
306.3
331.3
339.6
300330
333640
344760
363690
399780
411460
431940
469030
481240
6510
7235
7475
7825
8570
8810
9235
9995
10245
6275
6955
7180
7205
7900
8125
8340
9035
9260
31.7
31.8
31.8
32.8
32.9
32.9
33.3
33.3
33.3
3.03
3.03
3.03
3.17
3.17
3.17
3.24
3.24
3.24
4431
4432
4931
5174
5356
5345
198.3
208.8
230.7
258.4
305.4
342.4
173100
182100
227330
268440
330290
367400
4555
4790
5475
6310
7720
8585
4325
4555
5185
5890
7040
7935
26.2
26.2
27.8
28.6
29.1
29.0
2.54
2.54
2.76
2.87
2.96
2.92
3983
4492
4492
4492
5483
5483
5483
146.0
148.4
161.4
174.4
196.9
211.5
226.2
116000
131850
143590
155280
214670
230660
246580
3120
3490
3800
4110
5110
5490
5870
3065
3235
3525
3810
4835
5195
5555
25.0
26.4
26.4
26.4
29.3
29.3
29.3
2.40
2.57
2.57
2.57
2.81
2.81
2.81
Chapter 1/35
Piling Handbook, 8th edition (revised 2008)
Product information
z
y h
y
z
b
Table 1.16.2d Dimensions and properties of CAU, CU and CPU-R box piles
Section
b
h
mm
mm
Perim Sectional Total
Area
Section
Area
cm
cm2
CAU quadruple box piles
CAU 14 - 4
1222 1222
453
397
CAU 16 - 4
1225 1225
454
440
CAU 17 - 4
1226 1226
454
454
CAU 18 - 4
1258 1258
471
451
CAU 20 - 4
1261 1261
472
494
CAU 21 - 4
1262 1262
473
508
CAU 23 - 4
1263 1263
481
520
CAU 25 - 4
1266 1266
482
563
CAU 26 - 4
1267 1267
483
577
CU quadruple box piles
CU 12 - 4
1025 1025
388
337
CU 12 10/10 - 4 1025 1025
388
355
CU 18 - 4
1095 1095
417
392
CU 22 - 4
1115 1115
432
439
CU 28 - 4
1120 1120
445
519
CU 32 - 4
1120 1120
440
582
CPU-R quadruple box piles
CPU 8R-4
938
938
369
248
CPU 9R-4
1019 1019
391
252
CPU 10R-4
1019 1019
391
274
CPU 11R-4
1019 1019
391
296
CPU 13R-4
1136 1136
423
334
CPU 14R-4
1136 1136
423
359
CPU 15R-4
1136 1136
423
384
* The mass of welds is not taken into account
** Outside surface, excluding inside of interlocks
Chapter 1/36
Mass*
Moment
of inertia
y-y
cm4
z-z
cm4
cm2
kg/m
11150
11193
11206
11728
11771
11783
11977
12020
12033
311.6
345.0
356.2
354.0
387.6
398.6
408.4
441.6
452.8
692030
770370
796520
826550
910010
937100
979870
1064910
1093300
7565
7565
8231
8556
8799
8782
264.4
278.4
307.6
344.6
407.2
456.6
6958
7637
7637
7637
9376
9376
9376
194.7
197.9
215.2
232.5
262.5
282.1
301.6
Elastic
section
modulus
y-y
cm3
z-z
cm3
Min.
Coating
radius of area**
gyration
cm
m2/m
11325
12575
12990
13140
14430
14855
15510
16820
17250
41.7
41.8
41.9
42.8
42.9
43.0
43.4
43.5
43.5
4.02
4.02
4.02
4.20
4.20
4.20
4.30
4.30
4.30
394000
414830
507240
593030
725730
811100
7690
8095
9270
10635
12955
14480
34.2
34.2
36.0
36.8
37.4
37.3
3.36
3.36
3.65
3.80
3.93
3.87
268400
297710
325130
352430
490480
528080
565540
5725
5840
6380
6915
8640
9300
9960
32.9
34.4
34.4
34.5
38.3
38.3
38.4
3.18
3.41
3.41
3.41
3.70
3.70
3.70
Piling Handbook, 8th edition (revised 2008)
Product information
1.16.3 Special arrangements - CAZ + AZ combinations
bsys
y
y
AZ-sheet pile
AZ-box pile
Table 1.16.3
Section
Dimension
Mass 100
Mass 60
bsvs
mm
kg/m
kg/m
CAZ 13 / AZ 13
2680
147
126
60910
2000
CAZ 18 / AZ 13
CAZ 18 / AZ 18
2600
2520
156
163
134
139
95900
105560
2510
2765
CAZ 26 / AZ 13
CAZ 26 / AZ 18
2600
2520
188
196
166
173
151240
162660
3530
3795
CAZ 48 / AZ 13
CAZ 48 / AZ 18
2500
2420
255
265
232
241
283040
299290
5850
6190
CAZ 13-770 / AZ 13-7
3080
137
117
70740
2045
CAZ 18-700 / AZ 13-7
CAZ 18-700 / AZ 18-7
2940
2800
144
152
124
130
106220
118130
2530
2800
CAZ 26-700 / AZ 13-7
CAZ 26-700 / AZ 18-7
2940
2800
177
186
156
164
162840
177580
3530
3845
CAZ 39-700 / AZ 13-7
CAZ 39-700 / AZ 18-7
2940
2800
210
221
189
199
247340
266300
4930
5305
Mass
Mass
100
60
2
2
Moment
of inertia
Isvs/m
Elastic
section
modulus
Wsvs/m
cm4/m
cm3/m
LAZ = 100% Lbox pile
LAZ = 60% Lbox pile
Chapter 1/37
Piling Handbook, 8th edition (revised 2008)
Product information
1.16.4 Combined walls with U-type sections
1/1
1/2
1/3
1/4
Table 1.16.4
Section
1/1
Mass
kg/m2
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
AU box piles / AU sheet piles
AU 14
208
72530
3220
AU 16
230
82990
3660
AU 17
238
86450
3805
AU 18
236
98360
4045
AU 20
258
111160
4545
AU 21
266
115390
4705
AU 23
272
126050
5125
AU 25
294
139750
5645
AU 26
302
144350
5820
PU box piles / PU sheet piles
PU 12
220
56670
2810
PU 12 10/1 232
59300
2945
PU 18
256
96700
4090
PU 22
287
122900
4975
PU 28
339
160000
6415
PU 32
381
181330
7270
PU-R box piles / PU-R sheet piles
PU 8R
162
28970
1825
PU 9R
165
43080
2160
PU 10R
179
48210
2415
PU 11R
194
53280
2670
PU 13R
194
64560
2930
PU 14R
209
70390
3190
PU 15R
223
76150
3455
Chapter 1/38
1/2
Mass
kg/m2
1/3
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
Mass
kg/m2
1/4
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
Mass
kg/m2
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
156
173
178
177
194
199
204
221
226
40660
46230
48070
55020
61830
64080
69580
76800
79230
1805
2035
2115
2260
2525
2615
2830
3105
3195
139
153
158
157
172
177
182
196
201
43300
49560
51660
58990
66680
69250
75820
84080
86880
1920
2185
2275
2425
2725
2825
3080
3395
3505
130
144
148
148
162
166
170
184
189
37980
43440
45270
51760
58460
60700
66410
73590
76020
1550
1755
1820
1950
2180
2255
2435
2675
2755
165
174
192
215
255
285
32080
33480
54370
68730
88390
99790
1590
1660
2300
2785
3545
4000
147
155
171
192
226
254
33290
34820
58000
73940
96310
108660
1650
1730
2450
2995
3860
4355
138
145
160
180
212
238
29190
30520
50940
64920
84370
95070
1370
1430
1980
2395
3050
3445
122
124
135
145
146
157
168
16210
24460
27190
29880
36270
39360
42410
1020
1225
1365
1500
1645
1785
1925
108
110
120
129
130
139
149
16880
25650
28710
31730
38650
42130
45570
1065
1285
1440
1590
1755
1910
2065
101
103
112
121
122
131
140
14760
22550
25210
27830
33930
36960
39950
875
1050
1170
1290
1415
1535
1655
Piling Handbook, 8th edition (revised 2008)
Product information
1.16.4 Combined walls with U-type sections
Table 1.16.4 continued
Section
1/1
Mass
kg/m2
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
GU box piles / GU sheet piles
GU 7-600
157
30540
1745
GU 8-600
173
34600
1965
GU 9-600
190
38880
2195
GU 12-500 227
51590
2705
GU 13-500 243
56830
2965
GU 15-500 277
67490
3485
GU 16-400 310
63180
3760
GU 18-400 347
73800
4340
1/2
Mass
kg/m2
117
130
142
170
183
208
232
260
1/3
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
17300
19520
21850
29390
32290
38160
35270
41010
990
1110
1235
1540
1685
1970
2100
2410
Mass
kg/m2
104
115
127
151
162
185
207
231
1/4
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
17750
19990
22340
30290
33200
39040
36110
41990
1015
1135
1260
1590
1730
2015
2150
2470
Mass
kg/m2
98
108
119
142
152
173
194
217
Moment Elastic
of inertia section
modulus
cm4/m
cm3/m
15540
17480
19500
26590
29110
34150
31460
36530
850
955
1060
1325
1445
1695
1805
2075
Chapter 1/39
Piling Handbook, 8th edition (revised 2008)
Product information
1.16.5 Load bearing foundations
The development of rolled corner sections has enabled a new
generation of bearing pile to be created. By interlocking a number
of sheet piles with the same number of Omega bars a closed tube
results which can be driven into the ground sequentially. Using
equipment that installs piles without noise and vibration, the
ability to drive a closed section pile by pile means that load
bearing foundations made of steel can be installed at sensitive
sites and in urban areas where impact driven piles would not be
tolerated.
In addition to the reduction in environmental disturbance offered
by this system, the foundation is effectively load tested as it is
installed and can be loaded immediately. Furthermore, the
opportunity exists to extract the piles once the useful life of the
structure is passed in a reversal of the installation process.
Table 1.16.5 gives the dimensions and properties for foundations
created using 4, 5 and 6 sheet pile/omega combinations and
ultimate load capacities for both S270GP and S355GP steel
grades. The capacity of the foundation in geotechnical terms will
need to be assessed for the particular site location.
The effective radius of the pile (used for calculating torsional
resistance) is the value given in the column headed ‘Maximum
boundary distance’.
Fig 1.16.5
Chapter 1/40
Piling Handbook, 8th edition (revised 2008)
Product information
Table 1.16.5 Dimensions and properties for foundations using sheet
pile / omega combinations
Section
Steel Perimeter Moment
Radius
area
of inertia of gyration
cm2
mm
cm4
mm
Max
boundary
distance
mm
AU 16
4
5
6
531.2
664.1
796.8
4750
5950
7160
970430
1826530
3062970
427
524
620
632.7
784.5
928.9
15340
23285
32975
14342
17931
21514
18858
23575
28287
4.50
5.62
6.75
AU 20
4
5
6
585.5
731.8
878.2
4920
6170
7410
1114760
2083840
3476950
436
534
629
649.6
801.3
945.7
17160
26005
36765
15809
19759
23711
20784
25981
31177
4.67
5.84
7.01
AU 25
4
5
6
654.3
817.8
981.4
5020
6290
7560
1278190
2383790
3968200
442
540
636
652.4
804.1
948.5
19595
29645
41835
17666
22081
26498
23226
29033
34840
4.77
5.96
7.15
PU 12
4
5
6
428.5
535.7
642.8
4090
5130
6170
525260
983560
1645660
350
429
506
522.6
655.9
773.6
10050
14995
21275
11570
14464
17356
15213
19016
22819
3.84
4.80
5.76
PU 18
4
5
6
483.6
604.5
725.4
4380
5490
6600
645550
1194290
1979340
365
444
522
567.4
690.9
808.6
11380
17285
24480
13057
16322
19586
17167
21458
25750
4.13
5.16
6.19
PU 22
4
5
6
530.7
663.4
796.1
4520
5670
6820
735850
1353710
2233930
372
452
530
577.4
700.9
818.6
12745
19315
27290
14329
17912
21495
18840
23552
28260
4.27
5.34
6.41
PU 32
4 673.4
5 841.8
6 1,010.1
4580
5740
6900
964470
1771180
2915900
378
459
537
578.4
701.9
819.6
16675
25235
35575
18182
22729
27273
23905
29883
35857
4.33
5.41
6.49
PU 11R
4
5
6
390.2
487.7
585.3
4150
5170
6180
486560
908170
1516130
353
432
509
532.3
672.5
773.6
9140
13505
19600
10535
13168
15802
13851
17314
20777
3.90
4.84
5.77
PU 14R
4
5
6
453.3
566.6
679.9
4460
5560
6650
696450
1304470
2181080
392
480
566
589.8
740.5
858.6
11810
17615
25405
12238
15298
18358
16091
20114
24137
4.21
5.23
6.24
4
GU 13-500 5
6
403.9
504.9
605.9
3810
4740
5680
373590
693400
1153520
304
371
436
472.3
590.3
677.0
7910
11750
17040
10906
13633
16359
14340
17924
21509
3.56
4.41
5.27
3520
4380
5240
inside of
271530
499730
826250
interlocks
257
312
367
397.3
501.3
565.4
6835
9970
14615
11061
13827
16592
14544
18179
21815
3.27
4.05
4.83
4 409.7
GU 16-400 5 512.1
6 614.5
* = one side, excluding
Elastic
section
modulus
cm3
Ultimate axial capacity Coating *
area
S270GP
S355GP
kN
kN
m2
Chapter 1/41
Piling Handbook, 8th edition (revised 2008)
Product information
1.16.6 Jagged walls
Jagged walls may be formed by threading AZ piles together in the
reverse direction as illustrated below.
This arrangement results in a very wide system which is particularly
efficient for the creation of walls such as contamination barriers
where section strength is not the main criterion for pile selection,
but water-tightness and reduced costs for sealing are.
Fig 1.16.6a AZ Jagged wall
h
b
Table 1.16.6a AZ Jagged wall
Section
Sectional
area
Mass
Moment
of interia
b
mm
h
mm
Coating
area*
cm4/m
Elastic
section
modulus
cm3/m
cm2/m
kg/m2
AZ 12
AZ 13
AZ 14
718
718
718
185
186
187
117
128
139
92.1
100.3
109.1
2540
2840
3130
275
305
335
1.14
1.14
1.14
AZ 17
AZ 18
AZ 19
714
714
714
223
225
226
122
133
144
95.8
104.2
113.4
3840
4280
4720
345
380
420
1.19
1.19
1.19
AZ 25
AZ 26
AZ 28
736
736
736
237
238
239
158
169
181
124.3
132.9
141.8
6070
6590
7110
515
555
595
1.21
1.21
1.21
AZ 46
AZ 48
AZ 50
725
725
725
308
310
312
233
245
258
182.9
192.6
202.3
16550
17450
18370
1,070
1,125
1,180
1.30
1.30
1.30
AZ 13 10/10
AZ 18 10/10
718
714
187
225
133
139
104.7
109.0
2980
4500
320
400
1.14
1.19
AZ
AZ
AZ
AZ
12-770
13-770
14-770
14-770 10-10
826
826
826
826
181
182
182
183
112
117
123
128
87.9
92.1
96.2
100.4
2330
2460
2600
2730
255
270
285
300
1.12
1.12
1.12
1.12
AZ
AZ
AZ
AZ
17-700
18-700
19-700
20-700
795
795
795
795
212
212
213
214
117
123
128
134
92.0
96.2
101.0
105.0
3690
3910
4120
4330
330
350
365
385
1.16
1.16
1.16
1.16
AZ 24-700
AZ 26-700
AZ 28-700
813
813
813
241
242
243
150
161
172
117.7
126.6
135.4
5970
6500
7030
495
535
580
1.19
1.19
1.19
AZ 37-700
834
287
AZ 39-700
834
288
AZ 41-700
834
289
* One side, excluding inside of interlocks.
190
201
213
149.0
158.2
167.4
11600
12390
13170
810
860
910
1.22
1.22
1.22
Chapter 1/42
Dimensions
m2/m2
Piling Handbook, 8th edition (revised 2008)
Product information
It is also possible to arrange pairs of U piles to form a jagged wall
by connecting them together with Omega 18 special connectors.
In this arrangement, the pile pairs are orientated at 90° to each
other creating a deep wall with very high inertia and section
modulus. The choice of section for this type of wall must include
driveability criteria and the designer must ensure that the sections
are crimped or welded together in order to guarantee the shear
force transfer across the interlock on the neutral axis. Omega 18
connectors must also be welded if their contribution is taken into
account during design.
Fig 1.16.6b U Jagged wall
1.17 Cold formed sheet piles
Cold formed sheet piles increase the range of sections available
to designers particularly at the lower end of the section modulus
range. Manufactured in accordance with European standards,
cold formed sections are complementary to the range of hot rolled
sheet piles.
Cold formed sheet piles are normally used in the structural
protection of river banks from erosion and collapse. They are
recommended for retaining walls of medium height and are
particularly effective as containment walls at polluted sites.
Chapter 1/43
h
α
Form II standard
tseuqer no I mroF
N
b
Table 1.17.1
Type
Thickness System
Height
Angle
Other dimensions
width
Mass
single
e
b
h
α
M
N
pile
mm
mm
mm
°
mm
mm
kg/m
PAL3030
PAL3040
PAL3050
3.00
4.00
5.00
660
660
660
89.0
90.0
91.0
41
41
41
260
260
260
466
466
466
PAL3130
PAL3140
PAL3150
3.00
4.00
5.00
711
711
711
125.0
126.0
127.0
79
79
79
350
350
350
PAL3260
PAL3270
PAL3280
PAL3290
6.00
7.00
8.00
9.00
700
700
700
700
149.0
150.0
151.0
152.0
61
61
61
61
PAU2240
PAU2250
PAU2260
4.00
5.00
6.00
922
921
921
252.0
253.0
254.0
PAU2440
PAU2450
PAU2460
4.00
5.00
6.00
813
813
813
PAU2760
PAU2770
PAU2780
6.00
7.00
8.00
804
804
804
wall
Section
Inertia
modulus
Radius of
gyration
Cross Coating area (*)
section
single SSP
elastic
I
kg/m2
cm3/m
cm4/m
cm
cm2/m
m2/m
19.4
25.8
32.2
29.4
39.2
48.8
112
147
181
500
666
831
3.70
3.70
3.70
37.5
49.9
62.2
0.80
0.80
0.80
419
419
419
23.5
31.3
39.0
33.1
44.0
54.9
199
261
322
1244
1655
2063
5.40
5.40
5.40
42.2
56.1
70.0
0.97
0.97
0.97
299
299
299
299
471
471
471
471
46.2
53.2
61.6
70.0
66.0
76.0
88.0
100.0
413
479
545
605
3096
3604
4109
4611
6.10
6.10
6.10
6.00
84.1
96.8
112.1
127.4
0.92
0.92
0.92
0.92
48
48
48
252
252
252
725
725
725
39.0
48.7
58.3
42.3
52.8
63.3
404
504
600
5101
6363
7620
9.70
9.70
9.70
53.9
67.3
80.7
1.22
1.22
1.22
293.0
294.0
295.0
60
60
60
252
252
252
615
615
615
39.0
48.7
58.3
48.0
59.9
71.8
537
669
801
7897
9858
11813
11.40
11.40
11.40
61.1
76.3
91.4
1.22
1.22
1.22
295.0
296.0
297.0
60
60
60
252
252
252
615
615
615
60.4
70.4
80.3
75.1
87.5
99.8
803
934
1063
12059
14030
15995
11.20
11.20
11.20
95.7
111.4
127.1
1.16
1.16
1.16
Other thicknesses in the PAL and PAU series can be formed.
area
(*) 1 side, excluding inside of interlocks
Piling Handbook, 8th edition (revised 2008)
e
Product information
M
1.17.1 PAL and PAU sections
Chapter 1/44
Fig 1.17.1
Position B
Form II standard
Type
Thickness
Form I on request
Height
Angle
e
mm
System
width
b
mm
h
mm
α
°
M
mm
N
mm
PAZ4350
5.00
770
213.0
34
465
1078
208
182
38.2
49.6
448
4770
8.7
63.2
0.91
PAZ4360
6.00
770
214.0
34
465
1078
208
182
45.8
59.4
534
5720
8.7
75.7
0.91
PAZ4370
7.00
770
215.0
34
465
1078
208
182
53.3
69.2
619
6660
8.7
88.2
0.91
PAZ4450
5.00
725
269.0
45
444
988
203
177
37.7
52.0
612
8240
11.2
66.2
0.91
PAZ4460
6.00
725
270.0
45
444
988
203
177
45.1
62.2
730
9890
11.2
79.3
0.91
PAZ4470
7.00
725
271.0
45
444
988
203
177
52.4
72.3
846
11535
11.2
92.1
0.91
PAZ4550
5.00
676
312.0
55
444
890
203
177
37.7
55.8
772
12065
13
71.0
0.91
PAZ4560
6.00
676
313.0
55
444
890
203
177
45.1
66.7
922
14444
13
85.0
0.91
PAZ4570
7.00
676
314.0
55
444
890
203
177
52.4
77.5
1069
16815
13
98.8
0.91
PAZ4650
5.00
621
347.0
65
438
778
203
177
37.7
60.7
940
16318
14.5
77.3
0.91
PAZ4660
6.00
621
348.0
65
438
778
203
177
45.1
72.6
1122
19544
14.5
92.5
0.91
PAZ4670
7.00
621
349.0
65
438
778
203
177
52.4
84.4
1302
22756
14.5
107.5
0.91
O
mm
P
mm
Mass
Section
Per m of wall
Cross
single wall modulus Inertia
Radius
section
pile
elastic
I
of gyration
area
cm4
cm
cm2
kg/m kg/m2 cm3/m
Coating area (*)
single SSP
m2/m
(*) 1 side, excluding inside of interlocks
Piling Handbook, 8th edition (revised 2008)
Chapter 1/45
Other section and thickness PAZ’s can be formed.
Other dimensions
1.17.2 PAZ sections
Position A
Product information
Fig 1.17.2
Form II standard
Type
Thickness
Height
Angle
e
mm
System
width
b
mm
h
mm
α
°
M
mm
N
mm
O
mm
P
mm
Mass
Section
Per m of wall
Cross
single wall modulus Inertia
Radius
section
pile
elastic
I
of gyration
area
kg/m kg/m2 cm3/m
cm4
cm
cm2
PAZ5360
6.00
857
300.0
37
453
1245
192
173
54.3
63.3
766
11502
11.9
80.7
PAZ5370
7.00
857
301.0
37
453
1245
192
173
63.2
73.7
888
13376
11.9
93.9
1.04
PAZ5380
8.00
857
302.0
37
453
1245
192
173
72.1
84.0
1009
15249
11.9
107.1
1.04
PAZ5390
9.00
857
303.0
37
453
1245
192
173
81.0
94.4
1131
17123
11.9
120.3
1.04
PAZ5460
6.00
807
351.0
45
442
1149
180
167
53.9
66.8
968
16989
14.1
85.1
1.04
PAZ5470
7.00
807
352.0
45
442
1149
180
167
62.6
77.6
1123
19774
14.1
98.9
1.04
PAZ5480
8.00
807
353.0
45
442
1149
180
167
71.4
88.4
1277
22546
14.1
112.7
1.04
PAZ5490
9.00
807
354.0
45
442
1149
180
167
80.2
99.3
1431
25318
14.1
126.5
1.04
PAZ5560
6.00
743
407.0
55
438
1020
180
167
53.9
72.5
1233
25074
16.5
92.4
1.04
PAZ5570
7.00
743
408.0
55
438
1020
180
167
62.6
84.3
1432
29179
16.5
107.4
1.04
PAZ5580
8.00
744
409.0
55
438
1020
180
167
71.4
96.0
1628
33263
16.5
122.3
1.04
PAZ5590
9.00
744
410.0
55
438
1020
180
167
80.2
107.8
1825
37387
16.5
137.3
1.04
PAZ5660
6.00
671
451.0
65
434
875
180
167
53.9
80.3
1525
34340
18.3
102.3
1.04
PAZ5670
7.00
671
452.0
65
434
874
180
167
62.6
93.3
1770
39954
18.3
118.9
1.04
PAZ5680
8.00
672
453.0
65
434
874
180
167
71.4
106.3
2013
45537
18.3
135.4
1.04
PAZ5690
9.00
672
454.0
65
434
874
180
167
80.2
119.3
2259
51180
18.4
151.9
1.04
Other section and thickness PAZ’s can be formed.
Other dimensions
Form I on request
Coating area (*)
single SSP
m2/m
1.04
(*) 1 side, excluding inside of interlocks
Piling Handbook, 8th edition (revised 2008)
Position B
Product information
Position A
1.17.2 PAZ sections continued
Chapter 1/46
Fig 1.17.2
Piling Handbook, 8th edition (revised 2008)
Product information
1.17.3 Trench sheet sections
267
e
h
48
b
Table 1.17.3
Type
Thickness System
width
e
b
mm
mm
Height
Mass
h
mm
single
pile
kg/m
wall
kg/m2
Section
modulus
elastic
cm3/m
Inertia
Radius of
gyration
cm4/m
cm
Cross
section
area
cm2/m
Coating area(*)
single
SSP
m2/m
RC 8 600
6.0
742
92.0
40.9
55.1
194
896
3.6
70.2
0.87
RC 8 700
7.0
742
93.0
47.6
64.2
224
1045
3.6
81.8
0.87
RC 8 800
8.0
742
94.0
54.2
73.0
254
1194
3.6
93.0
0.87
(*) 1 side, excluding inside of interlocks
1.17.4 Threading options
PAZ sheet piles are usually delivered threaded in pairs and welded at
regular intervals using 100 mm runs of weld, the amount is dependent on
the length of the sheet piles.
Table 1.17.4
Series
30
PAL
31
PAL
30
X
X
PAL
31
X
X
PAL
32
PAU
22
X
X
PAU
24
X
X
PAU
27
PAZ
44
PAZ
54
PAZ
55
32
22
PAU
24
X
X
PAZ
54
55
X
X
X
X
X
X
X
X
27
44
X
X
X
Chapter 1/47
Piling Handbook, 8th edition (revised 2008)
Product information
1.17.5 Sheet pile assembly
Fig 1.17.5
PAL or PAU welded
assembly
PAZ welded T
assembly
75°
90°
90° and 0° bent
assembly
45° and 30° bent
assembly
30° and 30° bent
assembly
60°
Chapter 1/48
Piling Handbook, 8th edition (revised 2008)
Product information
1.17.6 Thickness
Maximum allowable thickness per type of sheet pile and grade of
steel
Table 1.17.6
Grade of steel
Series
S 235 JRC
S 275 JRC
S 355 JOC
PAL
30
5.0
5.0
4.5
PAL
31
5.0
5.0
4.5
PAL
32
9.0
9.0
7.0
PAU
22
6.0
6.0
5.0
PAU
24
6.0
6.0
5.0
PAU
27
8.0
8.0
6.5
PAZ
44
7.0
7.0
6.0
PAZ
54
9.0
9.0
7.5
PAZ
55
9.0
9.0
7.5
RC
8000
10.0
10.0
10.0
1.17.7 Handling holes
Table 1.17.7
The sheet pile sections can be provided with the following standard
handling holes
PAL 30-31
PAL 32
PAU
PAZ
Ø = 40 mm
Ø = 45 mm
Ø = 45 mm
Ø = 50 mm
Y = 150 mm
Y = 150 mm
Y = 200 mm
Y = 200 mm
Other dimension on request
Fig 1.17.7
Chapter 1/49
Piling Handbook, 8th edition (revised 2008)
Product information
1.17.8 Tolerances in accordance with EN 10249 Part 2.
Characteristics
Figures
SECTIONAL DEPTH
depth h
SECTIONAL WIDTH
width l
Nominal size
(in mm)
Tolerances
(in mm)
h ≤ 200
200 < h ≤ 300
300 < h ≤ 400
400 < h
± 4
± 6
± 8
± 10
single sheet piles
± 2% l
double sheet piles
± 3% l
e = 3,00
3,00 ≤ e ≤ 4,00
4,00 < e ≤ 5,00
5,00 < e ≤ 6,00
6,00 < e ≤ 8,00
8,00 < e ≤ 10,00
± 0,26
± 0,27
± 0,29
± 0,31
± 0,35
± 0,40
l
SECTIONAL THICKNESS
Section thickness tolerance is as specified in Table 3 of EN 10051
for a nominal width of steel strip or sheet of 1800 mm.
BENDING
Deflection (S)
0,25% L
Plan view
CURVING
Deflection (C)
0,25% L
Elevation
TWIST
Dimension (V)
LENGTH
SQUARENESS OF ENDS
Out-of-squareness (t) of end cuts:
MASS OF SECTIONS
Difference between total actual and total theoretical mass delivered:
Chapter 1/50
2% L
with
100 mm max
± 50
2%
of width
± 7%
Sealants
2
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Piling Handbook, 8th edition (revised 2008)
Sealants
Contents
Page
2.1
Introduction
1
2.2
Basements
1
2.3
Containment barriers
2
2.4
Demountable foundations
2
2.5
Site or factory application
3
2.6
How the sealants work
3
2.7
Installation techniques
4
2.8
Location of the sealants
5
Chemical durability
6
2.10
2.9
Permeability
6
2.11
Welding
7
2.12
Horizontal sealing
9
Piling Handbook, 8th edition (revised 2008)
Sealants
Piling Handbook, 8th edition (revised 2008)
Sealants
2.1 Introduction
The ability of retaining walls to prevent or restrict the passage of
ground water is of great importance in many applications e.g. in
basements, underground tanks, temporary cofferdams and
containment barriers.
A sealed sheet pile wall provides a safe, economic solution in any
situation where control of groundwater, to minimise the risk of
settlement of adjacent property and keeping excavations dry, is
an issue. The water-tightness of sheet pile interlocks almost
invariably improves with time but a sealant will provide a means
by which the flow/passage of water can be controlled
immediately.
All construction projects are unique with ground conditions and
installation methods varying from site to site; therefore the sealant
system adopted must be designed accordingly.
The integrity of a sealant system in use will depend upon it’s
suitability with respect to the method of pile installation adopted
and the ground conditions. Sealants are available to make driving
easier and systems are also available to protect the sealants when
driving the piles into gravels and difficult ground.
2.2 Basements
The use of permanent sheet piling for the walls of basement
structures has, until recently, been considered on relatively few
occasions partly because the interlocks were assumed to be a
potential leakage point. If a steel basement was built, the
interlocks would be seal welded following installation to give a
fully watertight wall. With narrow piles this would involve a
substantial amount of welding on site but following development
of wider piles, the amount of sealing to be carried out reduced
considerably making sealed basement walls a much more
attractive option. The development of new forms of sealant and
improved installation techniques means that sealed substructures
can now be created using non-welded piles.
The table below is extracted from BS 8102:1990, ‘The protection
of structures against water from the ground’ and indicates the
performance level required for the range of possible basement
grades. These are all achievable using steel sheet pile walls and
appropriate interlock sealants or sealing systems.
Chapter 2/1
Piling Handbook, 8th edition (revised 2008)
Sealants
Table 2.2 Extract from BS 8102 indicating basement
performance levels
Basement
grade
Basement usage
Performance level
1
Car parking; plant rooms
(excluding electrical
equipment); workshops
Some seepage and
damp patches tolerable
2
Workshops & plant rooms
requiring drier environment;
retail storage areas
No water penetration
but moisture vapour
tolerable
3
Ventilated residential &
working areas including
offices, restaurants etc.;
leisure centres
Dry environment
4
Archives and stores requiring
controlled environment
Totally dry environment
2.3 Containment Barriers
Sealed sheet pile cut off walls can be used to prevent leachate
from contaminated ground or refuse and disposal sites leaking
beyond the boundaries of the site.
Traditionally these barriers to horizontal movement of liquids have
been made using clay bunds or cement bentonite walls. These
traditional methods take up large areas of ground, are generally
formed away from the edge of the site and are prone to leakage.
It should be noted that concrete and slurry wall systems are
porous in the long term and, as they are both relatively brittle
materials, their ability to retain water will diminish if cracks appear
as a result of movement or exposure to loading fluctuations.
Sheet pile barriers offer a sealed solution on a much smaller
footprint and the barrier can be placed at the site boundaries to
maximise the ground area contained. Sheet piles used in
basements or as the foundations at the perimeter of a building
can also be sealed to prevent gases and leachate from
redeveloped brown field sites from entering the building.
Steel sheet piles can also be removed at a later date and reused
or recycled.
2.4 Demountable foundations
With the rapidly changing use of buildings and structures,
designers are required to take into consideration the demolition
and removal of the building at the end of its life. For a truly
sustainable design, this requirement should also include the
foundations.
Chapter 2/2
Piling Handbook, 8th edition (revised 2008)
Sealants
All steel pile foundations and retaining systems, including most
sealed pile walls, can be extracted and either reused or recycled.
This has the advantage that the site will be free of obstructions
and in a much better state to be redeveloped and is therefore less
likely to lose value in the long term.
2.5 Site or factory application
It has been shown by performance testing the various sealant
products that best results are obtained by thoroughly preparing
the interlocks prior to the application of the sealant. This has the
effect of removing any mill scale or other deleterious materials
from the interlock and producing a steel surface that the sealant
can properly adhere to. Not only is it difficult to clean and prepare
the interlocks to the required standard on the construction site but
weather conditions, temperature and humidity or the presence of
surface moisture may be detrimental to the bond between the
sealant and the steel. Interlock preparation to new piles will
ensure good adhesion of the sealant to the steel, reducing the risk
of damage when driving the piles and loss of performance in
service.
Once they have cured, most sealant products are inert and
therefore a non-hazard but handling the constituents requires care
as this operation introduces the possibility of exposure to
potentially hazardous substances and may involve working with
hot fluids. By applying sealants in the workshop, rather than on a
construction site, the handling of these materials can be
controlled by stringent safety standards. The work is confined to
experienced personnel operating in a controlled environment and
third parties are not subjected to unnecessary risk.
Once the sealants have cured, the safety risks reduce dramatically
so it is possible to carry out a risk assessment for sealant
application in the workshop that is complete as the operation is
carried out in a fixed and controlled environment. This does not
occur on the construction site where conditions will vary with
location.
2.6 How the sealants work
Sealant systems are designed to stop water penetrating the
interlocking joints in sheet pile walls and consequently the actual
performance of a sealant system will be a function of the interlock
geometry and amount of sealant applied by different suppliers.
Sealants can generally be said to operate in two ways; those that
create a compression seal between adjacent parts of the interlock
and those that displace to fill the voids. Compression sealants will
Chapter 2/3
Piling Handbook, 8th edition (revised 2008)
Sealants
generally resist greater water pressures than displacement sealants
but as indicated above, preparation of the steel surface is essential
to performance.
The sealants that are soft in texture when applied to the interlock
will generally perform as displacement seals when piles are
interlocked together as the material can be squeezed into the
voids in the interlocks preventing water flow. However these
sealants are usually supplied unprotected and performance can be
affected when driving in gravelly soil or by jetting.
Sealants that are firmer in texture will tend to be squashed during
installation and form a compression seal when piles are interlocked
together. They are generally more durable than displacement
sealants from both the design and installation points of view.
Hydrophilic compression sealants can also be supplied which have
a relatively low volume during the installation phase of a project
but swell up following contact with water to fill the voids in the
interlocks. The swelling action can occur if the sealant is wetted
accidentally by spraying or in heavy rain but a protected form of
hydrophilic sealant is available to overcome these issues.
In addition to the materials that are applied before driving, it is also
possible to seal weld the interlocks after installation. Further
information is given in 2.11.
2.7 Installation techniques
One of the best ways to minimise the risk of water ingress
through a sheet pile wall is to reduce the number of interlocks.
This can be achieved by selecting profiles with a larger system
width or, where installation conditions allow, it is recommended
that sheet piles are welded together into multiple units e.g. pairs
or triples and that they are driven in that form.
It has been found during site trials that pitch and drive methods to
install sheet piles are usually more practical than panel driving
when using pre-applied sealants. Traditionally, panel driving rather
than pitch and drive techniques, have been recommended to
improve the accuracy with which sheet piles are installed.
However, the need to work above ground level can make sealed
sheet piles more difficult to pitch and sequential driving may
disturb the sealants more. Dependant upon the type, more sealant
may be extruded before the piles have been fully driven when
panel driving.
Significant technological advances in sheet pile installation
equipment have facilitated pitch & drive methods. Telescopic
leader rigs and silent pressing machines have revolutionised pile
installation and, in the right conditions, it is now possible to install
piles accurately using this technique.
Chapter 2/4
Piling Handbook, 8th edition (revised 2008)
Sealants
To ensure good joint integrity it is important to control the
alignment of the piles in both the horizontal and vertical planes but
excessive corrective actions can damage the sealants. If it is
necessary to remove a pile then suitable repairs should be carried
out to the sealant before reuse. If repair is not practical, withdrawn
piles should be replaced by new ones.
It is essential not to overdrive sealed sheet piles with a vibratory
hammer as the heat generated by vibro driving may cause the
sealant to decompose or burn. If hard driving or refusal is
encountered it is recommended that vibro driving ceases at once.
The pile should then be driven to level with an impact hammer.
It has been found that displacement sealants can reduce friction in
the interlocks and make driving easier, but a compression sealant
can increase the interlock friction making pitching more difficult.
This will not normally be a problem for silent pressing machines
and telescopic rigs provided that the mast is of adequate size to
enable the piles to be pitched easily.
It is essential that any application of heat to interlocks containing
sealant, for example for cutting or welding, should only take place in
well-ventilated areas. Inhalation of smoke and vapours could be
harmful and should be prevented. It is the Contractor’s responsibility
to carry out adequate risk assessment procedures for any site
operations that involve handling damaged sealant substances,
welding, cutting or trimming of piles and carrying out repairs.
When trimming piles containing sealants using oxy acetylene
equipment, suitable fire extinguishing equipment and breathing
apparatus should be available.
2.8 Location of the sealants
Hydrophilic sealants should always be applied to the trailing
interlock to avoid early swelling. Parts of a sheet pile that will be
below excavation level in service cannot be economically sealed
after installation and, if required, the sealant system should be
applied before driving. Displacement or compression sealants
should be applied to the leading interlock when it is necessary to
seal the lower part of the pile.
If only the upper part of the pile requires sealant, a sealant system
suitable for application to the trailing interlock should be specified.
However it should not be forgotten that any exposed lengths of
sheet pile can be seal welded after driving to achieve the required
water tightness.
The sealant system may be curtailed above the bottom of the pile
if penetration into an impermeable strata is required and sealant is
not necessary over that part of the pile.
Chapter 2/5
Piling Handbook, 8th edition (revised 2008)
Sealants
Piles should always be specified and ordered long enough to
allow for trimming, in order that the piles and sealed lengths are
driven to the required depth. Please note that contractors and
designers should specify the distance from the top of the piles to
the start of the sealant if trimming with oxy-acetylene equipment
is foreseeable.
2.9 Chemical durability
After installation, the durability of the various sealant options in
the presence of a number of chemicals can be summarised as
follows:
Chemical
Hot applied bituminous Compressible sealant
product
product
Hydrophilic sealant
product
pH 3.5 to pH 11.5
Excellent
Excellent
Excellent
Seawater
Excellent
Excellent
Excellent
Mineral oil
Low
Excellent
Excellent
Petrol
Very low
Excellent
Excellent
Crude oil
Very low
No data available
Excellent
2.10 Permeability
The level of permeability achieved by an unsealed sheet pile wall will
depend on the soil conditions, the pile section chosen, the water head
and the quality of the installation. For this reason it is not easy to
predict the permeability of an unsealed wall with any degree of
accuracy. However when sealants have been applied to the interlocks
many of the variables are no longer relevant and the permeability of
the wall and sealant system as a whole may be assessed.
It is imperative for a wall to be watertight that the sheet piles must
interlock correctly at corners and junctions. De-clutching caused by
faulty installation practice has to be avoided.
A special de-clutching detector, Dixeran, has been developed by
ArcelorMittal to confirm that pile interlocking has been successfully
achieved. It is welded to the leading interlock of the previously
installed pile and gives a signal when the pile being installed has
reached the design toe position and is still interlocked. Further
information is available from the ArcelorMittal Technical Department.
Sealed and welded sheet pile walls should be impermeable if the
sealant system is performing adequately and as a sheet pile wall is
very resistant to structural loading, movements occurring after the
construction phase, that are sufficient to cause a seal to displace, are
not expected in the normal course of events.
Chapter 2/6
Piling Handbook, 8th edition (revised 2008)
Sealants
The following table gives an indication of the relative permeability
values for a number of sealant options.
Table 2.10 Relative permeability of sealant options
Approx
permeability
of system
ρ [10-10
m/s]
r (10-9 m/s)
100 kPa
200kPa
100 kPa
200 kPa
>1000(1 bar)
- (2 bar)
Sealing system
System
No sealant
Application of
Cost ratio1)
Application of
the system
the System
0
Interlock with
Beltan
Empty
Joints
<600 >100
not recommended
-
easy
-
1
TM
<600 < 60
not Not
recommended
recommended
easy
Easy
2.5
Interlock
with bituminous
Arcoseal product
Hot applied
TM
Interlock
with ROXAN
Compressible
sealantSystem
product
Welded
interlocksealing product
Hydrophillic
1)
Cost ratio =
0.3 ≤ 0.2
0
≤ 0.3
Cost of sealing system
Cost of bituminous sealing system
3 ≤ 0.2
0
0.3
2)
with care
Relatively easy5
2)
With Care 15
After excavation for the interlock
to be threaded on jobsite
2.11 Welding
Welding of the sheet pile interlocks is perhaps the most effective
way of permanently sealing sheet pile interlocks. This is
commonly carried out in basement construction where the
exposed face of the piling is easily accessed and water tightness
to Grade 2 or 3 as defined in Table 2.2 is required. However to
achieve a quality weld it is necessary to clean the surface and
carry out the welding in dry conditions. A special welding
procedure for this situation is available from the ArcelorMittal
Commercial RPS Technical Department.
Chapter 2/7
Piling Handbook, 8th edition (revised 2008)
Sealants
Fig 2.11.1
When the gap between adjacent interlocks is small enough, it is
possible to create a seal by applying a simple fillet weld across
the joint as illustrated above.
However, as sheet piling work is subject to on site tolerances, a
range of practical options have been developed to cope with gaps
of varying sizes.
Fig 2.11.2
Where the gap is too large to be bridged by a single pass,
introduction of a small diameter bar can be effective with a weld
run applied to either side of the joint to create the seal.
Fig 2.11.3
For wide gaps or where water is running through the interlock
making an acceptable weld difficult to achieve, by welding a plate
of sufficient width to suit the specific conditions across the joint it
is possible to create a vertical drain to channel any seepage away
from the weld.
Chapter 2/8
Piling Handbook, 8th edition (revised 2008)
Sealants
2.12 Horizontal sealing
In addition to sealing the walls of an underground structure, it is
also necessary to prevent water flow through the joint between
the walls and floor. As with many construction activities, attention
to detail and workmanship will ensure that the joint remains
watertight, but the picture below illustrates a simple waterstop
arrangement that can be formed by welding a plate to the piles
before it is cast into the base slab. In this example, a hydrophilic
strip has been attached to the plate to further enhance the
performance of this water barrier.
Fig 2.12
When designing the horizontal joint it is suggested that
consideration is given to welding the slab reinforcement to the
piles to prevent the concrete shrinking away as it cures thereby
creating a crack.
Chapter 2/9
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Durability
3
Piling Handbook, 8th edition (revised 2008)
Durability
Contents
Page
3.1
Introduction
1
3.2
Corrosion of piling in various environments
1
3.2.1
Underground corrosion of steel piles
1
3.2.2
Atmospheric corrosion
2
3.2.3
Corrosion in fresh waters
2
3.2.4
Corrosion in marine environments
3
3.2.5
Other environments
4
3.2.6
Localised corrosion
4
3.3
The effective life of steel sheet piles
6
3.4
Example durability calculations
3.5
Protection for new and existing structures
3.5.1
8
15
Measures for new structures
15
3.5.1.1
Use of a heavier section
15
3.5.1.2
Use of a high yield steel
16
3.5.1.3
Coating systems
16
3.5.1.4
Cathodic protection
17
3.5.1.5
Concrete encasement
18
Measures for existing structures
19
3.5.2.1
Plating of sections
19
3.5.2.2
Protective coatings
19
3.5.2.3
Cathodic protection
20
3.5.2.4
Frontal protection
20
3.5.2.5
Other protection options
20
Recommendations for various environments
21
3.5.2
3.6
Piling Handbook, 8th edition (revised 2008)
Durability
Piling Handbook, 8th edition (revised 2008)
Durability
3.1 Introduction
Steel piling is widely used in permanent earth retaining and
structural foundation works, and in the majority of circumstances
it can be used in an unprotected condition. The degree of
corrosion and whether protection is required depends upon the
working environment - which can be variable, even within a single
installation.
In general, marine environments are the most corrosive and
variable. In the few metres of vertical zoning which most
structures encompass, piles are exposed to underground,
seawater immersion, inter-tidal, splash and marine atmospheric
environments. For most environments characteristic corrosion
rates have been established. However, in some cases, localised
corrosion may occur, requiring detailed site examinations and
data analysis.
This chapter outlines the corrosion performance and effective life
of steel piling in various environments and reviews the protective
measures that can be taken to increase piling life in aggressive
environments.
3.2 Corrosion of piling in various environments
In determining the effective life of unprotected piles, the
selection of piling section and the need for protection it is
necessary to consider the corrosion performance of bare steels
in different environments. The corrosion data given for the
following environments indicate the loss of section where only
one face is exposed to the environment. In practice, opposite
sides of a piling structure may be exposed to different
environments. For example, one side of a harbour retaining wall
may be subject to a marine environment whilst the opposite side
is in contact with soil.
These situations are taken into account in 3.3, the tables of
corrosion losses being based on those given in Eurocode 3:
Part 5.
3.2.1 Underground corrosion of steel piles
The underground corrosion of steel piles has been studied
extensively. A review of published data, outlining mainly overseas
experiences, concluded that the underground corrosion of steel
piles driven into undisturbed soils is negligible, irrespective of the
soil type and characteristics; the insignificant corrosion attack
being attributed to the very low oxygen levels present in
undisturbed soils. Pitting corrosion in the water table zone is
frequently reported in the literature, but nowhere is this regarded
as affecting the structural integrity of piling, except for excessive
pitting found in some Norwegian marine sediments. Evaluations of
Chapter 3/1
Piling Handbook, 8th edition (revised 2008)
Durability
piles extracted from UK sites, ranging from canal and river
embankments through harbours and beaches to a chemical slurry
lagoon containing acid liquors (pH 2.8), also confirm negligible
underground corrosion losses.
A further evaluation in Japan of test piles driven into natural soils
at ten locations which were considered to be corrosive gave a
maximum corrosion rate of 0.015 mm/side per year after ten years
exposure.
An aspect of underground corrosion that can arise is that of
microbial corrosion by sulphate-reducing bacteria, which is
characterised by iron sulphide-rich corrosion products. Although
this form of corrosion has been observed on buried steel
structures, e.g. pipelines, there is no evidence from the literature
or within ArcelorMittal experience that this is a problem with
driven steel piles.
It is concluded that in natural, undisturbed soils steel pile
corrosion is very slight and, for the purpose of calculations, a
maximum corrosion rate of 0.012 mm/side per year can be used.
In the special case of recent-fill soils or industrial waste soils,
where corrosion rates may be higher, protective systems should
be considered.
3.2.2 Atmospheric corrosion
At inland sites, piles used for foundation work may also be used
as support columns or retaining walls above ground level. In such
cases bare steel will corrode in the atmosphere at a rate which
depends upon the site environment. In order of increasing
corrosivity, this can be broadly classified as rural, urban or
industrial. Similarly, piling at coastal sites may be subject to a
marine atmospheric environment.
Eurocode 3: Part 5 indicates that the atmospheric corrosion of
steel averages approximately 0.01 mm/side per year and this
value can be used for most atmospheric environments.
However, higher corrosion rates may be experienced in close
proximity to the sea or when pollution produces very
aggressive microclimates.
3.2.3 Corrosion in fresh waters
Fresh waters are very variable and can contain dissolved salts,
gases or pollutants which may be either beneficial or harmful to
steel. The term ‘fresh waters' is used to distinguish these from sea
or estuarine brackish waters.
Chapter 3/2
Piling Handbook, 8th edition (revised 2008)
Durability
The corrosion of steel in fresh waters depends upon the type of
water, although acidity/alkalinity has little effect over the range pH
4 to pH 9, which covers the majority of natural waters. Corrosion
losses from fresh water immersion generally are lower than for sea
water and effective lives are normally proportionately longer.
However fresh waters are very variable and these variable
conditions are reflected in the guidelines on corrosion rates given
in Eurocode 3: Part 5.
3.2.4 Corrosion in marine environments
Marine environments normally encompass several exposure zones of
differing aggressivity and the corrosion performance of marine
structures in these zones requires separate consideration. Factors
which can contribute to loss of pile thickness due to localised
corrosion are also considered in 3.2.6. Information on loss of section
thickness with time is given in tables 3.3.1 and 3.3.2.
Below the Bed-Level
Where piles are below the bed level very little corrosion occurs
and the corrosion rate given for underground corrosion is
applicable, i.e. 0.012 mm/side per year.
Sea Water Immersion Zone
Above the bed-level, and depending upon the tidal range and
local topography, there may be a continuous seawater immersion
zone in which, with time, piling exposed to unpolluted waters
acquires a protective blanket of marine growth, consisting mainly
of seaweeds, anemones and seasquirts. Corrosion of steel piling
in immersion conditions therefore is normally low.
Tidal Zones
This zone lies between the low-water neap tides and high-water
spring tides and tends to accumulate dense barnacle growths
with fiIamentous green seaweeds. The marine growths again give
some protection to the piling, by sheltering the steel from wave
action between tides and by limiting the oxygen supply to the
steel surface.
Corrosion investigations show that rust films formed in this zone
contain lime, derived from barnacle secretions, which also helps
to limit the long term corrosion rate of steels to a level similar to
that of immersion zone corrosion.
Low Water Zone
At the low water level, where a lack of marine growth is observed,
higher corrosion rates are often experienced. It has been
established that, for piles in tidal waters, the low water level and
the splash zone are regions of highest thickness losses.
Chapter 3/3
Piling Handbook, 8th edition (revised 2008)
Durability
Higher corrosion rates are sometimes encountered at the low water
level because of specific local conditions and it is recommended
that periodic inspection of these areas is undertaken.
Splash and atmospheric zones
Above the tidal zone are the splash and marine atmospheric
zones, the former being subject to wave action and salt spray and
the latter mainly to airborne chlorides. Unlike the tidal zone, these
zones are not covered with marine growths. In the splash zone,
which is a more aggressive environment than the atmospheric
zone, corrosion rates are similar to the low water level, i.e. 0.075
mm/side per year. In this zone thick stratified rust layers can
develop and at thicknesses above about 10 mm these tend to
spall from the steel, especially on curved parts of the piles such
as the shoulders and the clutches. However, it should be borne in
mind that rust has a much greater volume than the steel from
which it is derived and steel corrosion losses may amount to no
more than 10% to 20% of the rust thickness.The boundary
between the splash and atmospheric zones is not well defined;
however, corrosion rates diminish rapidly with distance above
peak wave height and the mean atmospheric corrosion rate of
0.02 mm/side per year can be used for this zone.
3.2.5 Other environments
The corrosion performance of piling in natural environments has
so far been considered. For environments such as industrial waste
tips, land reclamation schemes or those affected by man-made
pollution, guidelines on corrosion rates are given in Eurocode
3:Part 5.
3.2.6 Localised corrosion
Localised corrosion can occur particularly in marine environments
and recently anomalous corrosion effects have been observed in
parts of structures within a number of ports throughout Western
Europe. In these cases, highly localised corrosion has occurred at
the low water level which conforms to a specific pattern. This
form of localised corrosion has become known as 'accelerated
low water corrosion'.
Localised corrosion in the low water zone
This form of corrosion has been experienced on sheet piles, pipe
piles, and H sections and on parts of fabricated structures, e.g.
angle and channel sections and plate material. These products
have been produced by various manufacturers in Europe and
Japan and therefore this phenomenon is not restricted to a
particular section or steel manufacturer. Localised corrosion at the
low water level has been investigated in Japan where it is termed
Chapter 3/4
Piling Handbook, 8th edition (revised 2008)
Durability
'concentrated corrosion'. In a recent survey of port and harbour
authorities throughout five Western European countries it was
found that, on steel sheet piles, the localised corrosion followed a
distinct pattern. In almost all cases the effect was confined to the
outpans of sheet piled walls in a zone at, or just below, the mean
low water level. The inpans were almost invariably unaffected. On
'U' shaped piles, this corrosion is most severe in the centre of the
outpans, whilst for 'Z' shaped piles, the effect tends to be
concentrated on the corners or webs of the outpans. Corrosion
rates of 0.3 - 0.8 mm/year have been observed in these
circumstances.
In extreme cases, pile thickness reductions in the outpan areas
may lead to the premature formation of localised holes or slits in
the steel. This can cause a reduction in structural integrity and in
some cases, loss of fill material from behind the wall.
Factors affecting localised corrosion
In marine environments, localised higher rates of corrosion can be
caused by several mechanisms, individually or in combination, as
discussed below:a. Macro-cell effects have been found to occur on steel sheet
piling in tidal waters where a range of corrosive environments
is experienced. Research investigations have shown that
potential differences exist between the various zones that
occur in a marine environment such that the low water zone is
anodic with respect to the tidal zone and that a corrosion
peak occurs at the low water level due to the formation of a
large differential aeration cell. The macro-cathode of this cell
being in the tidal zone, where oxygen is available for the
cathodic reduction reaction, and the macro-anode being in
the adjacent low water zone. These macro-cell effects will
vary depending upon local conditions.
b. Continual removal of the protective corrosion product layer
through abrasion or erosion, by the action of fendering
systems, propeller wash, bow-thrusters, waterborne sands
and gravels or repeated stresses, can lead to intense localised
corrosion. The area where the rust layer is continually
removed becomes anodic to the unaffected areas, particularly
in the low water zone where macro-cell effects are strongest.
c. In some cases, localised corrosion at the low water level has
been associated with microbiological activity. A detailed
evaluation of corrosion products from affected structures
indicates the presence of compounds e.g. sulphides, which
stimulate localised corrosion. It is considered that these
compounds are associated with the presence of a consortia
of bacteria including sulphate reducing bacteria and aerobic
species.
Chapter 3/5
Piling Handbook, 8th edition (revised 2008)
Durability
d. Bi-metallic corrosion can occur where steel is electrically
connected to other steels, metals or alloys, having nobler
potentials or where weld metals are significantly less noble than
the parent material. Corrosion is concentrated in the less noble
steel, often at the junction between the dissimilar materials.
e. Discontinuous marine fouling by plants and animals can
accelerate the corrosion rate in localised areas because of
differential environmental conditions caused by their presence
(resulting in the formation of differential aeration cells etc.) or
possibly by their biological processes. However, dense
continuous marine growth can stifle general corrosion by
impeding the diffusion of oxygen to the steel surface.
f.
Stray currents entering the structure from improperly
grounded DC power sources can cause local severe localised
damage at the point where the current leaves the structure.
3.3 The effective life of steel sheet piles
The effective life of unpainted or otherwise unprotected steel
piling, depends upon the combined effects of imposed
stresses and corrosion.
Performance is clearly optimised where low corrosion rates
exist at positions of high imposed stresses.
The opposite faces of a sheet pile may be exposed to
different combinations of environments. The following tables
indicate the mean loss of thickness due to corrosion for these
environments in temperate climates over a given life span.
Table 3.3.1 Loss of thickness [mm] due to corrosion for piles
and sheet piles in soils, with or without groundwater
5 years
25 years
50 years
Undisturbed natural soils (sand, silt
clay, schist, ...)
Required design working life
75 years 100 years
0,00
0,30
0,60
0,90
1,20
Polluted natural soils and industrial
grounds
0,15
0,75
1,50
2,25
3,00
Aggressive natural soils (swamp,
marsh, peat, ...)
0,20
1,00
1,75
2,50
3,25
Non-compacted and non-aggressive
fills (clay, schist, sand, silt, ...)
0,18
0,70
1,20
1,70
2,20
Non-compacted and aggressive fills
(ashes, slag, ...)
0,50
2,00
3,25
4,50
5,75
Notes:
1) The values given are only for guidance
2) Corrosion rates in compacted fills are lower than those in noncompacted ones. In compacted fills the figures in the table should
be divided by two.
3) The values given for 5 and 25 years are based on measurements,
whereas the other values are extrapolated.
Chapter 3/6
Piling Handbook, 8th edition (revised 2008)
Durability
Table 3.3.2 Loss of thickness [mm] due to corrosion for piles
and sheet piles in fresh water or in sea water
Required design working life
Common fresh water (river, ship canal, ...)
in the zone of high attack (water line)
5 years
25 years
50 years
75 years 100 years
0,15
0,55
0,90
1,15
1,40
Very polluted fresh water (sewage, industrial
effluent, ...) in the zone of high attack
(water line)
0,30
1,30
2,30
3,30
4,30
Sea water in temperate climate in the zone
of high attack (low water and splash zones)
0,55
1,90
3,75
5,60
7,50
Sea water in temperate climate in the zone
permanent immersion or in the intertidal zone
0,25
0,90
1,75
2,60
3,50
Notes:
1) The values given are only for guidance.
2) The highest corrosion rate is usually found at the splash zone or at
the low water level in tidal waters.
However, in most cases, the highest bending stresses occur in the
permanent immersion zone,
3) The values given for 5 and 25 years are based on measurements,
whereas the other values are extrapolated.
The corrosion losses quoted are extracted from Eurocode
3:part 5 and based upon investigations carried out over many
years on steel exposed in temperate climates. While the
values quoted are considered to be relevant to the design and
performance of most sheet piling structures, in some
circumstances the designer may have local knowledge which
leads to the adoption of higher values.
For combinations of environments where low water corrosion
is involved, higher losses than those quoted have been
observed at or just below the low water level mark and it is
recommended that periodic inspection is undertaken.
Recent fill ground or waste tips will require special
consideration.
Chapter 3/7
Piling Handbook, 8th edition (revised 2008)
Durability
3.4 Example durability calculations
To establish the pile section needed for a given effective life in a
specific environment it is necessary to follow the procedure
below:
1
Establish the corrosion losses for each zone using tables
3.3.1, and 3.3.2.
2
Using the bending moment diagram Fig 3.4b establish the
maximum bending moment in each corrosion zone.
3
Calculate the minimum required section modulus for each
corrosion zone.
4
Using the graphs in 3.4.1, 3.4.2 and 3.4.3 determine the most
appropriate section giving the required minimum section
modulus after the loss of thickness calculated in step 1
above.
Fig 3.4a Design cross section
Chapter 3/8
Fig 3.4b Typical marine wall bending
moments
Piling Handbook, 8th edition (revised 2008)
Durability
Using the design cross section and bending moment diagrams
given in Figs 3.4a and 3.4b, assess the pile section needed to
give a 50 year design life.
Step 1
Depth
0
1
5
6
12
Step 2
-
1m
5m
6m
12m
18m
Face
1
Soil
Soil
Soil
Soil
Soil
Face
2
Splash
Tidal
Low Water
Immersion
Soil
Total thickness loss
over 50 year life (mm)
4.35
2.35
4.35
2.35
1.2
Depth
Maximum ultimate bending moment
0
1
5
6
12
10kNm/m
440kNm/m
520kNm/m
590kNm/m
370kNm/m
-
1m
5m
6m
12m
18m
This example is based on the use of S390GP steel and hence a
Yield Stress of 390N/mm 2 is used to determine the minimum
section modulus needed for each corrosion zone.
Step 3
Step 4
Depth
Minimum section modulus
0
1
5
6
12
10x10 x 1.2/390 = 31cm /m
-
1m
5m
6m
12m
18m
3
3
3
3
3
3
3
3
3
3
440x10 x 1.2/390 = 1354cm /m
520x10 x 1.2/390 = 1600cm /m
590x10 x 1.2/390 = 1815cm /m
370x10 x 1.2/390 = 1139cm /m
From the critical minimum section modulus requirements calculated in
Step 3 and the appropriate thickness loss from step 1
(Zmin = 1815cm3/m, t = 2.35mm or Zmin = 1600cm3/m, t = 4.35mm)
an appropriate pile section can be selected: in this case, AZ 25 in grade
S390GP steel is to be adopted.
With application of a coating suitable for marine exposure conditions, an
additional 20+ years can be anticipated.
Chapter 3/9
Piling Handbook, 8th edition (revised 2008)
Durability
3.4.1a Elastic section modulus against loss of thickness AZ piles
Chapter 3/10
Piling Handbook, 8th edition (revised 2008)
Durability
3.4.1b Elastic section modulus against loss of thickness AZ piles
AZ 41-700
AZ 39-700
AZ 37-700
AZ 28-700
AZ 26-700
AZ 24-700
AZ 20-700
AZ 19-700
AZ 18-700
AZ 17-700
AZ 14-770-10/10
AZ 14-770
AZ 13-770
AZ 12-770
Chapter 3/11
Piling Handbook, 8th edition (revised 2008)
Durability
3.4.2 Elastic section modulus against loss of thickness AU piles
Chapter 3/12
Piling Handbook, 8th edition (revised 2008)
Durability
3.4.3a Elastic section modulus against loss of thickness PU piles
PU 32
PU 28
PU 28-1
PU 22
PU 22-1
PU 18
PU 18-1
PU 15R
PU 14R
PU 13R
PU 12 10/10
PU 12
PU 11R
PU10R
PU 9R
PU 8R
Chapter 3/13
Piling Handbook, 8th edition (revised 2008)
Durability
3.4.3b Elastic section modulus against loss of thickness GU piles
GU 18-400
GU 16-400
GU 15-500
GU 13-500
GU 12-500
GU 9-600
GU 8-600
GU 7-600
Chapter 3/14
Piling Handbook, 8th edition (revised 2008)
Durability
3.5 Protection for new and existing structures
In many circumstances steel corrosion rates are low and the use
of protective systems etc. is not necessary. However, there are
circumstances where corrosion of steel piling can be more
significant:
In these circumstances methods of increasing the effective life of
a structure may need to be considered and the measures that can
be taken include the following:
(a) Use of a heavier section
(b) Use of a high yield steel at mild steel stress levels
(c) Applying a protective organic coating or concrete encasement
(d) Applying cathodic protection
If a sheet piling wall is to be constructed in an area which may be
prone to localised corrosion, one or more of the specified
measures to provide the desired effective life should be
considered at the design stage to allow for the possibility of
higher corrosion rates on unprotected steel piles particularly at or
around the low water level. (Given the effects are highly localised,
the additional expense involved in engineering a repair, when
necessary, to account for the phenomenon is often modest in the
context of the overall project cost).
Consideration should be given to the provision of an engineered
solution to structures which are likely to be subject to abrasion or
erosion. The effects of abrasion and erosion should also be taken
into account when methods of corrosion protection are being
considered, e.g. the use of a paint coating.
3.5.1 Measures for new structures
3.5.1.1 Use of a heavier section
Effective life can be increased by the use of additional steel
thickness as a corrosion allowance. The extra steel thickness
required depends upon the working life and environment of the
piling structure. The thickness losses for steel piling in various
service environments have been outlined in 3.3. In determining this
corrosion allowance it is important to consider the stress distribution
in the structure in order to locate the region where corrosion losses
can be least tolerated. It is possible that the most corrosive zones
will not coincide with the most highly stressed zone and therefore, in
many circumstances, the use of a corrosion allowance can be a cost
effective method of increasing effective life.
Alternatively, it may prove more economical to increase the pile
thickness locally in the low water zone by the attachment of
plates. Typically, these will need to be 2-3m in length.
Chapter 3/15
Piling Handbook, 8th edition (revised 2008)
Durability
3.5.1.2 Use of a high yield steel
An alternative approach to using mild steel in a heavier section is
to use a higher yield steel and retain the same section. Although
all grades of carbon steel have similar corrosion rates, the
provision for example, of grade S355GP sheet piles to EN10248
designed to grade S270GP stresses will allow an additional 30%
loss of permissible thickness to be sustained without detriment.
This method, in effect, builds in a corrosion allowance and gives
an increase of 30% in effective life of a steel piling structure for an
increase of less than 2% in steel costs. An even greater
performance increase can be achieved by specifying S390GP or
S430GP steels for piles designed to S270GP stresses.
3.5.1.3 Coating systems
Atmospheric exposure.
In industrial and coastal regions, the corrosion process may be
accelerated by the presence of salt and/or industrial pollution –
particularly sulphur dioxide. The life of conventional paints is
rather short, resulting in frequent maintenance periods. The use of
heavy duty epoxy/polyurethane systems will extend the time to
first maintenance and reduce the overall cost of steel protection.
Sheet piling is often used in situations where part of it is exposed
to the atmosphere, for example as a retaining wall. In such
applications, the aesthetic and functional look is important. A coal
tar epoxy finish or a rusty surface are unlikely to be acceptable
and so polyurethane finishes become an automatic choice. They
combine gloss and colour retention and the latest formulations are
easy to apply and maintain.
Suggested system:
Zinc silicate epoxy primer
Re-coatable epoxy intermediate coating
Aliphatic polyurethane topcoat
Nominal dry film thickness of the system 240 µm
Fresh water immersion.
Fresh water is usually less corrosive than sea water although
brackish or polluted water conditions can still be quite severe.
There are often aesthetic considerations in fresh water projects.
For convenience a system has been chosen which is capable of
performing well both above and below water avoiding the need to
apply separate systems and hence saving time and cost.
The proposed system is tar free and suitable for both immersion
and atmospheric exposure. Where maximum colour and gloss
retention is required, a polyurethane finish may be applied as a
topcoat.
Chapter 3/16
Piling Handbook, 8th edition (revised 2008)
Durability
Suggested system:
Polyamine cured epoxy coating
Nominal dry film thickness of the system 300 µm
Seawater immersion.
Structures continuously or partially immersed in sea water require
careful attention. Abrasion and impact (direct or indirect) may
damage the coating system and soluble salts from the sea will
accelerate the rate of corrosion for the damaged areas.
For long term performance in immersed conditions, there should
be no compromise on quality. The specification must be clear and
the surface preparation must be good.
The application must be properly carried out and inspected and
the coating system must be of high quality. Cathodic protection is
often specified in combination with a coating system and it is
essential that the chosen coating system has been fully tested for
compatibility.
Suggested system:
Polyamide cured epoxy primer
Polyamide cured coal tar epoxy coating
Nominal dry film thickness of the system 450 µm
(As an alternative, glass flake reinforced epoxy coating could
be used with the appropriate primer and sealer).
Waste disposal.
Sheet piling is increasingly being used to isolate severely
contaminated ground. It is also used to contain polluted soil
which has been moved from other areas. Here, an excellent
standard of steel protection is essential. The coating system may
have to protect the steel from highly acidic soil. It must have an
outstandingly good chemical resistance and especially good
resistance to mineral and organic acids. The system must be able
to withstand abrasion and impact.
Suggested system:
Micaceous iron oxide pigmented polyamide cured epoxy primer
Polyamine cured epoxy coating with increased chemical
resistance
Nominal dry film thickness of the system 480 µm
3.5.1.4 Cathodic protection
The design and application of cathodic protection systems to
marine piled structures is a complex operation requiring the
knowledge and experience of specialist firms. The principles
involved are outlined below.
Two systems are employed, utilising either sacrificial anodes or
impressed DC currents. In normal electrochemical corrosion all
Chapter 3/17
Piling Handbook, 8th edition (revised 2008)
Durability
metal-loss occurs at the anode and both types of CP system
impart immunity from corrosion by rendering the steel structure
cathodic to externally placed anodes. Bare steel structures initially
require an average current density at about 100 mA/m 2 in
seawater, but this value normally falls over a long period of
continuous operation to within the range 30 to 70 mA/m 2.
Therefore, for a sheet piled structure of large surface area, the
total current required could be considerable. If piles are coated
below the water level then, depending upon the type of coating
employed, current requirements are considerably reduced and
can be as low as 5mA/m2. Deterioration of the protective coating
occurs with time, though this is counteracted to some extent, by
the deposition of protective calcium and magnesium salts on bare
areas of the sheet piling and the growth of marine organisms.
However, in the long term, an increase in total current may be
necessary and the cathodic protection system should be
designed with an appropriate margin of capacity to cover this
situation. Not all protective coatings can be used in conjunction
with cathodic protection. The coating should be of high electrical
resistance, as continuous as possible, and resistant to any alkali
which is generated by the cathodic reaction on the steel surface.
The coating system suggested for sea water immersion in 3.5.1.3
can be used with cathodic protection.
When considering cathodic protection it should be borne in mind
that this method is considered to be fully effective only up to the
half-tide mark. For zones above this level, including the splash
zone, alternative methods of protection are required.
Sacrificial anode or impressed current alone or in conjunction
with CP compatible protective coating systems have been
evaluated and recommended as a method of protection against
localised corrosion at the low water level in both Europe and
Japan. These evaluations include bioreactor tests in the
presence of bacteria.
It is considered that CP is effective at sea bed level where
localised corrosion occurs due to sand eroding away the
corrosion product layer (rather than the steel surface). However,
sand erosion prevents the deposition of protective calcareous
deposits normally formed during CP and, therefore, the
protective current density would be higher than typical values.
3.5.1.5 Concrete encasement
Concrete encasement can be used to protect steel piles in marine
environments. Often the use of concrete is restricted to the splash
zone by extending the concrete cope to below the mean high
water level. However, in some circumstances, both splash and
tidal zones are protected by extending the cope to below the
lowest low water level.
Chapter 3/18
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Durability
Experience has shown that where the splash zone is only partially
encased, a narrow zone of increased corrosion can occur at the
steel-concrete junction. This is a result of electrochemical effects
at the steel-concrete junction, i.e. a potential difference is
generated between steel in concrete and in seawater which,
combined with the effects of differential aeration at the junction,
causes the exposed steel immediately adjacent to the concrete to
become anodic and corrode preferentially.
Concrete is not itself always free from deterioration problems. It
normally has a pH value of about 12 to 13 and within this pH
range steel remains passive and corrosion is superficial. However,
diffusion of chloride ions into the concrete from seawater can
break down steel passivity and stimulate the corrosion reactions.
Therefore, concrete for protecting steel in seawater must be of
good quality, i.e. have high strength, good bonding
characteristics, low permeability and be free initially from
chlorides. It must also provide adequate cover and be properly
placed and cured. If these requirements are not met, then rust
formed from corrosion of the steel piles or steel reinforcement
within the concrete can exert sufficient pressure to spall the
concrete and expose the steel to the marine environment.
Remedial work on partially spalled concrete and exposed steel is
difficult and expensive.
With correct design and the use of good quality concrete,
encasement is an effective method of increasing the working life
of a steel piling structure.
3.5.2 Measures for existing structures
3.5.2.1 Plating of sections
Affected areas of a sheet pile wall can be 'thickened' by the
attachment of plates, which can also be used to repair holes and
slits. Welding of plates is feasible in either wet or dry conditions
but the latter is normally preferable to avoid the necessity for
divers and special techniques. Limpet dam type devices can be
used to dewater around the affected regions and allow welding in
dry conditions. After repair, further protective measures can be
considered such as the application of a protective coating or
cathodic protection.
3.5.2.2 Protective coatings
Protective coatings can be applied on site to areas affected by
localised corrosion. However, it should be noted that surface
preparation and cleanliness as well as the properties of the
coating are critical to long-term durability.
Chapter 3/19
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Durability
Surface tolerant coatings are available that can be applied under
dry conditions using a limpet dam. Such devices have limited
depth and enable application of coatings to below the low water
level but not necessarily down to bed level.
Solvent free coatings also have been developed that can be
applied and will cure under water using special application
equipment which enables large surface areas to be treated. Two
coats are normally applied to minimise the possibility of through
coating defects and such coatings can be applied to bed level.
3.5.2.3 Cathodic protection
Cathodic protection can be retrofitted to affected or repaired
structures. Provided the structure to be protected is electrically
continuous and is maintained at the correct protection potential, a
good degree of attenuation of corrosion effects is feasible.
3.5.2.4 Frontal protection
In the extreme, a new steel face to the piled wall can be created
by driving a row of shorter piles in front of the existing structure
and connecting them together. Concrete may be used to fill the
gap. Thus, the front wall may be allowed to corrode away
completely without prejudicing the integrity of the overall
structure. Obviously, such measures will be impractical in many
circumstances owing to the geometrical requirements for berthing
etc.
3.5.2.5 Other protection options
Some developments that are being carried out at the time of
writing are outlined below.
An electrochemical method is being developed for the treatment
of localised corrosion during its early stages. The affected area is
electrochemically cleaned, sterilised and subsequently coated
with a calcareous deposit, formed from the salts dissolved in
seawater, which protects the treated surface from further
corrosion. However, the long term durability of the coating
remains to be validated.
Water based cementitious modified polymer coatings are available
which are tolerant of on-site conditions and have given long term
durability on steel surfaces at coating thicknesses of about 2mm.
These coatings are being further developed so that they can be
spray applied on-site at economical rates.
Alternatives to existing underwater coatings are currently being
developed and tested.
Chapter 3/20
Piling Handbook, 8th edition (revised 2008)
Durability
3.6 Recommendations for various environments
The recommendations outlined below are based on the corrosion
data given in 3.3 for the various environments and on our
experience. Where local conditions are likely to impair life, for
example where the piling is subject to localised corrosion, these
circumstances have also been considered.
Underground exposures
Steel piles driven into undisturbed ground require no protection
irrespective of the soil types encountered. This also applies to
piles driven into harbour, river and sea beds.
For piling driven into recent fill soils and particularly industrial fill
soils some protection may be necessary, though each case
should be judged on its merits. Where protection is required it is
recommended that a durable protective organic coating is applied
to a dry film thickness of 480 microns (see 3.5.1.3).
Seawater immersion exposures
Normally the corrosion rate of steel immersed in seawater is low
enough to give acceptable steel loss over the design life of a
piling structure. Therefore bare steel can be used in immersion
conditions. Alternatively, paint coatings or cathodic protection can
be used to achieve the required design life.
Fresh water immersion exposures
For practical purposes, the situation is the same as for seawater
immersion and corrosion is low enough to permit the use of bare
steel. In fresh water immersion conditions, protective organic
coatings would be expected to last longer.
Fresh water exposures at or above the water level
In non-tidal situations, corrosion can occur at the water line of
piled river embankments and, more usually, canals where these
support roughly a constant water level. On smaller canals where
this is likely to be a problem, protected trench sheets are normally
used. On larger canals etc., where piling is more often used, it is
recommended that a protective organic coating is applied to a
depth of 1 m above and below the water level to a dry film
thickness of 300 microns on the water side. At areas other than
the water line, protection is unnecessary. However, if the section
of piling above water level is required to be painted for aesthetic
reasons, then a protective coating can be used above the
recommended 1 m level, depending upon the cost and durability
requirements.
Where the water level is variable, protective systems are
unnecessary. However, if painting above the water line is required
for aesthetic reasons then again, depending upon requirements,
protective coatings can be used.
Chapter 3/21
Piling Handbook, 8th edition (revised 2008)
Durability
Marine tidal exposures
Tidal zones tend to accumulate marine fouling which affords some
protection to the underlying steel and acceptable corrosion rates
occur over this zone, although a corrosion peak tends to occur at
the low water level. Bare steel with an appropriate corrosion
allowance can be used or alternatively, the design life can be
achieved through the use of a paint coating or cathodic
protection. Localised corrosion can occur at the low water level
and possible corrosion protection measures that can be applied
are discussed in 3.5.2.
Marine splash zone exposures
This zone, together with the low water level, presents the most
corrosive conditions for steel and several options exist. In many
circumstances bare steel can be used with a corrosion allowance
where appropriate. The ASTM standard claims that Grade A690
steel (Mariner grade) gives a performance improvement of 2 to 3
times that of conventional carbon steel in marine splash zone
conditions. Alternatively, protection can be employed in the form
of organic coatings or concrete encasement. With the former it is
recommended that the coating be applied to a dry film thickness
of 450 microns and should extend to at least 1 m below mean
high water level. It should be borne in mind that, in the absence of
good borehole data, it is often impossible to estimate beforehand
the driven depth of piling. In such cases more of the pile length
may have to be coated to ensure that the piles in situ are
protected in the splash zone. The ease and effectiveness of
maintenance will depend upon local conditions, for instance the
degree of shelter from wave action.
Where the tidal range is small concrete encasement can also be
used. With this method the cope should be extended to a
minimum of 1 m below mean high water level and the highest
quality concrete used. Good coverage of the encased steel
should be ensured.
Atmospheric exposures
Piling exposed to rural, urban or industrial atmospheres is usually
painted for aesthetic reasons.
A variety of coatings can be used depending upon requirements.
Where aesthetic considerations are of prime importance, some
coatings can be overcoated on-site with a polyurethane finish
coat.
These coatings can also be used where sheet piled bridge
abutments or other piled land-sited structures are subject to road
salt spray or where piled walls or bridge abutments are hidden by
stand-off brick or stone facias.
Chapter 3/22
Piling Handbook, 8th edition (revised 2008)
Durability
The marine atmosphere zone of a piling structure is normally
considered on the same basis as the splash zone and if
protection is used on the splash zone then it is normally extended
to protect the atmospheric zone.
Chapter 3/23
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Earth and
water pressure
4
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Contents
Page
Notation
1
4.1
Introduction
3
4.2
Determination of soil properties
3
4.3
Types of boreholes samples
and methods of testing
5
4.3.1
Cohesionless soils (gravel, sand etc.)
5
4.3.2
Cohesive soils (clays and silts)
6
4.3.3
Mixed soils (sand with clay, sand with silt)
7
4.3.4
Rock
7
4.3.5
Geophysical methods of site investigation
7
4.3.6
Chemical analysis
8
4.3.7
Seepage water
8
4.4
Information required for design of steel sheet
pile retaining walls and cofferdams
8
4.5
Typical soil properties
9
4.6
Earth pressure calculation
9
4.7
Short term, total stress analysis
11
4.8
Long term, effective stress analysis
12
4.9
Tension crack
15
4.10
Groundwater pressures
16
4.11
Permanent structures
17
4.12
Temporary structures
17
4.13
Battered walls
18
4.14
Concentrated and linear surcharge
18
4.15
Sloping ground surface
19
4.16
Earth pressure calculation
19
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Piling Handbook, 8th edition (revised 2008)
Notation
Units
Bulk “weight density” of soil
kN/m3
Saturated “weight density” of soil
kN/m3
γ′
Submerged “weight density” of soil
kN/m3
γw
“Weight density” of water
kN/m3
c′
Effective cohesion
kN/m2
c′d
Design cohesion value (effective stress)
kN/m2
c′mc
Moderately conservative value of effective
cohesion
kN/m2
δ
Angle of wall friction
degrees
δ max
Limiting angle of wall friction between soil
and piles
degrees
Fs
Factor of safety
-
Fsc ′
Factor applied to the effective cohesion value
-
Fs ø ′
Factor applied to the effective angle of
shearing resistance
-
F ss u
Factor applied to the undrained shear strength
-
Ka
Coefficient of active earth pressure
-
K ac
Active pressure coefficient for cohesion
-
γ
γ
sat
Kp
Coefficient of passive earth pressure
-
K pc
Passive pressure coefficient for cohesion
-
pa
Intensity of active earth pressure (total stress)
p′a
Intensity of active earth pressure (effective stress) kN/m2
pp
Intensity of passive earth pressure (total stress)
kN/m2
p′p
Intensity of passive earth pressure
(effective stress)
kN/m2
ø
Total stress angle of shearing resistance
degrees
ø′
Effective stress angle of shearing resistance
degrees
ø′crit
Critical state angle of shearing resistance
(effective stress parameter)
degrees
ø′mc
Moderately conservative value of shearing
degrees
resistance of the soil (effective stress parameter)
ø′d
Design angle of shearing resistance
(effective stress)
continued
kN/m2
degrees
Chapter 4/1
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Notation
Units
q
Surcharge Pressure
kN/m2
su
Undrained shear strength (total stress)
kN/m2
s ud
Design Undrained shear strength (total stress)
kN/m2
s umc
Moderately conservative value of
undrained shear strength (total stress)
kN/m2
s wmax
Limiting value of wall adhesion (total stress)
kN/m2
u
Water pressure
kN/m2
z
Depth
m
“Weight Density” in kN/m3 can be readily converted to Mass
Density” in kg/m3 by multiplying by 102.
Types of soil
1 Cohesionless soils: granular materials such as sand, gravel,
hardcore, rock, filling etc.
2 Cohesive soils: clays and silts. Under certain conditions chalk
and other similar materials can be treated as cohesive soils
3 Mixed soils: combinations of groups 1 and 2 such as sand with
clay, or sand with silt.
4 Rock
Chapter 4/2
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
4.1 Introduction
The assessment of soil stratification and assignment of
appropriate engineering parameters is a fundamental part of the
design process for an embedded retaining wall. The soil not only
creates the forces attempting to destabilise the wall but also
provides the means by which stability is achieved so an
understanding of the importance of soil in the design of retaining
walls is paramount.
It is assumed that the reader has a basic knowledge of soil
mechanics and consequently this chapter is included as a
refresher for some of the principles on which retaining wall design
is based.
Soil parameters for use in design calculations should, wherever
possible, be obtained by sampling and testing material from the
job site but indicative parameter values are included in this
chapter for use in preliminary calculations.
The amount and complexity of data needed to carry out the
design of a retaining wall is, to an extent, governed by the
calculation method to be used. For example, if the analysis is to
be carried out on the basis of limiting equilibrium, relatively simple
soil data can be used to obtain a satisfactory answer but if the
problem is to be analysed using finite element techniques, the
data input required to adequately describe the behaviour of the
soil is significantly more complex. Additional or more complex soil
data will involve a greater site investigation cost and it is often the
case that the client is not prepared to sanction greater expenditure
at this stage of a project. In many cases, however, the additional
cost is easily recouped by avoiding false economies and
conducting a more sophisticated analysis.
4.2 Determination of soil properties
Site Investigation, Boreholes, Soil Sampling and Testing
The precise and adequate determination of site conditions prior to
the commencement of any form of civil engineering construction
work is necessarily regarded as standard practice.
Where piled foundations, cofferdams, retaining walls etc. are to be
driven it is essential that as much information as possible be
obtained regarding strata, ground water, tidal water,
embankments, existing foundations, buried services and the like in
order to design the most suitable piling in terms of strength,
stability and economy.
Full use should therefore be made of all available information, no
matter how old, regarding previous investigation of the proposed
site and its surroundings. Such information should be
supplemented with data obtained from borehole sampling and
testing, the number of boreholes depending upon the size and
nature of the site.
Chapter 4/3
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
For piling work, the number of boreholes, or other form of
investigation, should be adequate to establish the ground
conditions along the length of the proposed piling and to
ascertain the variability in those conditions. The centres between
boreholes will vary from site to site but should generally be at
intervals of 10 to 50m along the length of the wall. The depth of
the investigation will be related to the geology of the site; it is
recommended that boreholes be taken down to at least three
times the proposed retained height. To assess the precise nature
of the ground, samples should be taken at regular intervals within
this depth or wherever a change in stratum occurs.
If ground anchorages are proposed, the ground investigation
should be of sufficient extent and depth to provide data for the
strata in which the anchorages will attain their bond length.
Samples obtained by the borehole method must be correctly
labelled to avoid possible error. Duplicate records of all boreholes
giving depth and location, should also be maintained.
Table 4.2 Field Identification of Soils
Very Soft
Exudes between fingers when squeezed in fist.
Soft
Can be readily excavated with a spade and can be easily
moulded by substantial pressure in the fingers.
Firm
Can be excavated with a spade and can be remoulded by
substantial pressure in the fingers.
Stiff
Requires a pick or pneumatic spade for its removal and
cannot be moulded with the fingers.
Very Stiff
Requires a pick or pneumatic spade for its removal and will
be hard and brittle or very tough.
Many stiff clays exist in their natural state with a network of joints
or fissures. A large piece of such clay, when dropped, will break
into polyhedral fragments. If possible, it should be determined
whether the clay is fissured or intact, as this could be a criterion in
the design of steel sheet pile structures.
Chapter 4/4
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
4.3 Types of borehole sample and methods of testing
4.3.1 Cohesionless soils (gravel, sand etc)
Air tight jar or bag samples (disturbed) are normally forwarded to
the laboratory for scientific analysis. When examined on site, this
should be carried out by a qualified engineer or geologist.
Table 4.3.1 Relationship of In-situ Tests to Relative Density of
Cohesionless Soils
Relative
Standard
Cone
ø′
Density
Penetration
Test
‘N’ Value
Penetration
Test
‘q s’ (MN/m2 )
(Degrees)
Very Loose
0-4
2.5
25
Loose
4-10
2.5-7.5
27.5
Medium Dense
10-30
7.5-15.0
30
Dense
30-50
15.0-25.0
35
Very Dense
Over 50
Over 25.0
40
(TESPA – Installation of Steel Sheet Piles)
Standard Penetration Test (in-situ density)
The resistance offered by a cohesionless soil to a 50mm external
diameter thick-walled sample tube when driven into the bottom of
a borehole can be approximated to the relative density of the soil
encountered. It is usual to neglect the first 150mm of penetration
because of possible loose soil in the bottom of the borehole from
the boring operations. The force applied is that of a free-falling
load of 64kg travelling 760mm before impact, the number of
blows (N) per 300mm of penetration being recorded. See Table
4.3.1 for interpretation of results.
Beware of false values in very fine grained soils when the stratum
is subject to high groundwater pressure. Under these conditions it
is possible for the bottom of the borehole to blow while the SPT
test equipment is being put into the borehole creating very loose
conditions for the test that will not be realised in practice.
Shear Box Test.
Used to determine the angle of internal friction. Because granular
soils are relatively free draining, any excess pore water pressures
developed, even under rapid loading, will dissipate readily. Hence
the results of this test will always give effective stress values (ø′).
Chapter 4/5
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Mechanical Analysis.
This comprises two stages involving the separation of coarser
particles by means of sieves and determination of the size of finer
particles by a special sedimentation process known as wet
analysis. The subject of mechanical analysis exceeds the scope of
this type of handbook. Reference should be made to appropriate
literature for methods of procedure.
4.3.2 Cohesive soils (clays and silts)
Shear strength. Two distinct methods of testing are given as the
correct procedure, ie “direct” shear tests and “indirect” shear
tests.
Direct shear testing involves the use of the Vane Test in which a
metal vane is pushed into the soil in the borehole and torque
applied. Measurement of the resultant angle-of-twist in the
transmitting rod or spring indicates the magnitude of the torque,
hence, the strength of the sample material.
Indirect shear tests are carried out on undisturbed samples in two
forms:
1 Triaxial Compression Test wherein a cylindrical specimen
(undrained) is subject to a constant lateral hydrostatic pressure
whilst the axial pressure is steadily increased to the yield point
of the material.
The test will give the ‘total’ stress parameters of ø and su for all
types of clay.
In the absence of site-specific data the undrained shear
strength value (su), of the clay, can be deduced from the soil
descriptions shown in table 4.3.2.1.
Table 4.3.2.1 Relationship between soil consistency and undrained
shear strength.
Chapter 4/6
Consistency of Clay
Undrained
Shear Strength (su)
(kN/m2)
Very Soft
<20
Soft
20 - 40
Firm
40 - 75
Stiff
75 - 150
Very Stiff
150 - 300
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
When “effective” stress parameters are required (ø′ and c′), a
drained triaxial test should be performed, with the strain rate
sufficiently low to ensure the dissipation of pore water pressures.
If no effective stress parameters are available from triaxial tests,
Table 4.3.2.2 may be used for initial design studies in conjunction
with an effective cohesion value c′=0.
Table 4.3.2.2 Relationship of Plasticity Index to the critical
angle of shearing resistance for cohesive soils.
Plasticity Index
%
ø′crit
(degrees)
15
30
30
25
50
20
80
15
2 Unconfined Compression Test which measures the shear
strength of undrained cohesive soils under zero lateral
pressures by means of a special test apparatus, normally
portable.
Natural Moisture Content. Determination of the natural or in-situ
moisture content of a soil sample by weighing before and after
drying the sample in a ventilated oven at 105°C. The loss of
weight is expressed as a percentage of the final or “dry weight”.
4.3.3 Mixed soils (sand with clay, sand with silt)
The method referred to in “Cohesive Soils” may be applied to the
testing of mixed or combined soils.
4.3.4 Rock
The resistance to drilling is a good indication of strata material
strength. Where possible, especially during the exploration of
virgin territory, samples of rock should be obtained for analysis.
4.3.5 Geophysical methods of site investigation
Information produced as a result of this type of survey should be
used only to supplement borehole sampling. It should not be
regarded as an alternative method to site investigation.
Chapter 4/7
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
4.3.6 Chemical analysis
The destructive influence of natural deposits and buried waste or
industrial effluent should be fully investigated during soil sampling
and testing. Examination will reveal the suitability of the anticorrosion measures referred to in Chapter 3, or the need for
special precautionary measures.
When sealants are to be used in the pile interlocks, and where
tests indicate aggressive compounds within the groundwater, for
example in landfill sites, the suitability of the sealant product
should be checked. Further information and advice on sample
testing may be obtained from the ArcelorMittal brochure ‘The
Impervious Steel Sheet Pile Wall – Practical Aspects’.
4.3.7 Seepage water The effect which water has on the engineering properties of a soil
must be clearly understood and carefully considered during the
site investigation period. In addition to the tests on individual soil
samples, the direction of seepage, upwards and downwards,
should be determined before any decision is reached on the
design of a piling system.
4.4 Information required for the design of steel sheet pile retaining walls
and cofferdams
Having determined the precise nature of the ground within the site
and ascertained the individual soil properties, it is desirable to
release certain basic information to the piling designer to ensure
the best possible arrangement in terms of strength and economy.
The minimum details should include the following:
• Copies of relevant site drawings showing the projected retaining
wall/cofferdam areas and the proximity of roads, rail or crane
tracks, buildings, embankments, viaducts and waterways.
• Information regarding any underground workings, surface traffic
loadings, capital plant or heavy machinery which could be
affected by piling operations or in turn, affect ground stability by
vibration.
• Copies of actual borehole logs, soil analyses and test reports.
• Details of any faults or fissures encountered during drilling.
• Details of seasonal rainfalls, standing water levels, tidal waters
and the depths of off-shore reaches. Stream and river velocities,
currents etc, should be given where possible.
Chapter 4/8
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
4.5 Typical soil properties
Table 4.5 Typical Moderately Conservative Soil Properties
Soil
Loose
Compacted
Loose or Compacted
Bulk
Bulk
Bulk
Bulk
Submerged Submerged
Density “Weight Density “Weight
Density
“Weight
Density”
Density”
Density”
kg/m3 kN/m3
kg/m3 kN/m3
kg/m3
kN/m3
Angle of Internal Friction Undrained
Loose Compacted
Shear
ø′
ø′
Strength
Su
Degrees
Degrees
kN/m2
Fine Sand
1750
17.2
1900
18.6
1050
10.3
30
35
0
Coarse Sand
1700
16.7
1850
18.2
1050
10.3
35
40
0
Gravel
1600
15.7
1750
17.2
1050
10.3
35
40
0
Brick Hardcore
1300
12.8
1750
17.2
800
7.9
40
45
0
Quarry Waste
1500
14.7
1750
17.2
1000
9.8
40
45
0
Rock Filling
1500
14.7
1750
17.2
1000
9.8
40
45
0
Slag Filling
1200
11.8
1500
14.7
900
8.8
30
35
0
Ashes
650
6.4
1000
9.8
400
3.9
35
40
0
Peat
-
-
1300
12.8
300
3.0
-
5
5
River Mud
1450
14.2
1750
17.2
1000
9.8
-
5
5
Loamy Soil
1600
15.7
2000
19.6
1000
9.8
-
10
10
Silt
-
-
1800
17.7
800
7.9
-
10
10
Sandy Clay
-
-
1900
18.6
900
8.8
-
0
15 to 40
Very Soft Clay
-
-
1900
18.6
900
8.8
-
0
<20
Soft Clay
-
-
1900
18.6
900
8.8
-
0
20 to 40
Firm Clay
-
-
2000
19.6
1000
9.8
-
0
40 to 75
Stiff Clay
-
-
2100
20.6
1100
10.8
-
0
75 to 150
Very Stiff Clay
-
-
2200
21.6
1200
11.8
-
0
>150
NOTE: Soil properties should normally be obtained from ground
investigation wherever possible.
4.6 Earth pressure calculation
Calculation of Earth Pressures using Limit State Design
Current standards and codes of practice used in the design of
embedded retaining walls favour limit state design philosophy.
The limit states to consider are the Ultimate Limit State (ULS),
which represents the state at which failure of all or part of the wall
occurs, and the Serviceability Limit State (SLS), which represents
the state, short of failure, beyond which specific service
performance requirements are no longer met.
It is important from the outset that the designer establishes the
performance criteria of the wall, as this will assist in determining
Chapter 4/9
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
which limit state will govern the design, and then demonstrate that
the ultimate or serviceability limit state will not be exceeded over
the design life of the wall.
It is generally recognised that the loading conditions under ULS
are normally more severe than the SLS condition, however there
are cases, (for example in the design and construction of urban
basements), when SLS conditions (wall deflections, associated
ground movements, watertightness etc.), are just as critical as the
structural integrity of the wall in the ULS condition.
In limit state design calculations it is usual practice to apply a
mobilisation/partial factor to the principal uncertainties, which in
geotechnical design tends to be soil strength. A direct adjustment
on the other hand, is normally made to any uncertainties in
groundwater pressure, excavation depth and ground levels etc.
Application of a mobilisation factor to soil strength is often referred
to as the Factor on Strength method, and is incorporated in many
of the established codes of practice. The value of the factor used
is dependent on the standard/code of practice adopted, whether
the design case is that of ULS or SLS, the soil strength parameter
under review and also whether the soil parameters are moderately
conservative or worst credible values.
Moderately conservative values are generally defined as being a
cautious best estimate. They are considered to be equivalent to
characteristic values as defined by EC7(1994) or representative
values as defined in the United Kingdom Standard BS8002 (1994).
Worst credible values on the other hand are the worst case values
that the designer believes might occur or values that are
considered unlikely, in practice
Generally, for ULS calculations, a factor of safety greater than 1.0
is applied to moderately conservative soil strength parameters, or
Fs=1.0 if using worst credible values. The more onerous of these
two sets of parameters is then used for the ULS design. With SLS
calculations, moderately conservative soil strength parameters are
used with Fs=1.0.
For the ULS design examples in this handbook, representative
moderately conservative soil values have been used. The
mobilisation factors used are those shown in section 4.7 (Short
term, total stress analysis) and section 4.8 (Long term effective
stress analysis).
The factored design soil strength parameters are used to
determine the earth pressure coefficients that increase the earth
pressures on the retained side and reduce the earth pressures on
the restraining side as the mobilisation factor increases above
unity.
Chapter 4/10
Piling Handbook, 8th edition (revised 2008)
The pressure applied to a vertical wall, when the ground surfaces
are horizontal are calculated as follows
Active pressure = p a = γ .z.tan 2(45 - ø )-2.s u .tan(45 - ø )
2
2
Passive Pressure = p p = γ .z.tan 2(45 + ø )+2.s u .tan(45 + ø )
2
2
The terms
tan 2(45 - ø ) and tan 2(45 + ø )
2
2
can be more conveniently referred to as Ka coefficient of active
earth pressure and Kp coefficient of passive pressure respectively.
Hence p a = K a γ .z – 2.s u . √ K a
and p p = K p γ .z + 2.s u . √ K p
The above expressions however do not allow for the effects of
friction and adhesion between the earth and the wall. They are
based on extensions of the Rankine Equation (by the addition of
cohesion), from ‘Earth Pressures’ – A.L. Bell: Proceedings of the
Institute of Civil Engineers, Vol. 199 - 1915.
Subsequent research has further developed these formulae to
allow for the effects of wall friction, wall adhesion etc on the earth
pressure coefficients. These are shown in 4.7 and 4.8 of this
chapter.
The above formulae represent the total stress condition. For
effective stress the undrained shear strength parameter of the soil
(su) is simply replaced by the effective cohesion value of the soil, c′.
4.7 Short term, total stress analysis
The short term total stress condition represents the state in the
soil before the pore water pressures have had time to dissipate
i.e. immediately after construction in a cohesive soil. The initial
(total stress) parameters are derived from undrained triaxial tests –
section 4.3.2.
For total stress the horizontal active and passive pressures are
calculated using the following equations :
p a = K a ( γ .z + q ) – s u K a c
p p = K p ( γ .z + q ) + s u K pc
where
( γ .z + q ) represents the total overburden pressure
K a = K p = 1.0 for cohesive soils.
Chapter 4/11
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Design s u = s ud = s umc / Fs s u where Fssu is typically 1.5.
The earth pressure coefficients, Kac and Kpc, make an allowance
for wall /soil adhesion and are derived as follows :
K ac= K pc= 2 .
√ (1+s s
w max
ud
)
The limiting value of wall adhesion swmax at the soil/sheet pile
interface is generally taken to be smaller than the design
undrained shear strength of the soil, sud, by a factor of 2 for stiff
clays. i.e. Sw max = α x Sud, where α = 0.5. Lower values of wall
adhesion, however, may be realised in soft clays.
A range of α values and corresponding Kac and Kpc values are
shown in Table 4.7.1.
Table 4.7.1
α=
s wmax
sud
Values of
K a c and K p c
0.00
2.00
0.25
2.24
0.50
2.45
In any case, the designer should refer to the design code they are
working to for advice on the maximum value of wall adhesion they
may use.
4.8 Long term, effective stress analysis
The long term effective stress condition represents the state when
all the excess pore water pressures, within the soil mass, have
dissipated. i.e. the drained state.
Cohesionless soils are free draining, therefore excess pore water
pressures created during construction, will dissipate so quickly
that “effective stress” conditions exist in both the short and long
term. Hence ø′ is used throughout.
In cohesive soils, the change from total stress (undrained
conditions) to effective stress (drained conditions) generally occurs
over a much longer period of time. The exception being the
presence/addition of fine silts/granular material which can greatly
reduce the time in which effective stress conditions are reached.
During this period the strength parameters of the cohesive soil may
change significantly due to pore water pressures changes induced
following construction of a retaining structure. The change in
strength is caused by equalisation of negative pore water pressure
Chapter 4/12
Piling Handbook, 8th edition (revised 2008)
in the soil and results in reduced values of cohesion c′ but
increased values of angle of internal friction (ø′).
Whilst all cohesive soils are subject to these changes, the
effective stress condition is not usually critical when fine silts and
naturally consolidated and slightly over consolidated clays, ie
those with cohesion values of less than about 40kN/m2, are
involved, since the change from effective parameters gives an
overall increase in soil strength. However, the reverse is true for
over-consolidated clays, ie those with undrained values in excess
of about 40kN/m2. The overall strength will, in most cases, be
reduced as the stress condition changes from total to effective
because the loss of substantial cohesive strength is not
compensated adequately by the increasing angle of internal
friction. Hence it is advised that for cohesive soils both short and
long term stress analyses be carried out to determine the more
onerous design case.
For effective stress analysis the horizontal active and passive
pressures are calculated using the following equations :
p′a = K a ( γ z – u + q ) – c′d K a c
p′p = K p ( γ z – u + q ) + c′d K p c
where:
γ z – u + q represents the effective overburden pressure
design c′ = c′d = c′mc / Fsc′ where Fsc′ is typically 1.2,
and K a, K p, K ac and K pc are the coefficients of lateral earth
pressure.
The effects of wall friction on active and passive pressures are
taken into account by using modified values of K a and K p and
substituting K ac and K pc for the terms 2.√ K a and 2.√ K p
respectively. It is usual to assume no wall adhesion in effective
stress analysis and hence this term has been omitted from the
formulae.
In determining Ka and Kp the limiting value of wall friction, δ max,
is traditionally taken to be less than the angle of shearing
resistance of the soil. This is to allow for variations in roughness at
the soil/wall interface and also soil movements associated with
the transfer of lateral load to the wall. The designer should refer to
the adopted design code to determine whether particular values
of wall friction are specified but care is also required to ensure
that the sign conventions in the code are obeyed. Positive values
of δ are usually used for active pressures (resultant acting
downwards) and negative values for passive pressures (resulting
acting upwards).
Chapter 4/13
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
For examples in this Handbook the limiting value of wall friction
is taken to be δ max = + 2/3 ø′d on the active and passive sides
of the wall.
Generally, wall friction is beneficial to the stability of the wall by
reducing the value of Ka on the retained side, and increasing Kp in
the soil in front of the wall. This is based on the assumption that
the soil behind the wall (i.e. on the retained side) moves
downwards relative to the wall, and heaves upwards in front of the
wall (passive side) as the wall takes up the lateral loading from the
ground. There are instances however, when the direction of soil
movement in front or behind the wall may not be beneficial to wall
stability - as is normally assumed. For example, load bearing piles,
where the pile may move downwards relative to the soil on both
sides, or an activity such as dewatering / tunnelling which may
cause the soil at the front of the wall to settle. In such cases the
direction of the angle of wall friction may change, resulting in
much higher active earth pressure coefficients and much lower
passive earth pressure coefficients, hence the need for care when
selecting appropriate wall friction values.
Values of Ka and Kp are given in tables 4.8.1 and 4.8.2. The design
angle of shearing resistance ø′d is determined as follows :
Design ø′ = ø′d = tan-1 (tan ø′mc / Fsø′) where Fsø′ is typically 1.2.
Table 4.8.1 Values of K a
Values
of ø′mc
(°)
Chapter 4/14
Values of δ
Values
of ø′d
(°)
0
0.00
0.00
1.000
1.000
1.000
5.00
4.17
0.864
0.842
0.837
10.00
8.36
0.746
0.710
0.702
15.00
12.59
0.642
0.599
0.590
20.00
16.87
0.550
0.504
0.494
25.00
21.24
0.468
0.423
0.413
30.00
25.69
0.395
0.352
0.343
35.00
30.26
0.330
0.291
0.282
40.00
34.96
0.271
0.238
0.229
45.00
39.81
0.219
0.191
0.184
1/
2
ø′d
2/
3
ø′d
Piling Handbook, 8th edition (revised 2008)
Table 4.8.2 Values of K p
Values
of ø′mc
(°)
Values
of ø′d
(°)
0.00
Values of δ
0
– 1/2 ø′d
– 2/3 ø′d
0.00
1.000
1.000
1.000
5.00
4.17
1.157
1.193
1.200
10.00
8.36
1.340
1.431
1.451
15.00
12.59
1.557
1.732
1.772
20.00
16.87
1.818
2.122
2.193
25.00
21.24
2.136
2.638
2.761
30.00
25.69
2.531
3.347
3.554
35.00
30.26
3.032
4.356
4.712
40.00
34.96
3.684
5.864
6.493
45.00
39.81
4.558
8.256
9.421
The above tables represent earth pressure coefficients where the
ground surface behind the wall is horizontal. The values of Ka and
Kp are derived using equations from EC7 (1995) Annex G. For
sloping surfaces, and for differing values of wall friction the reader
may wish to refer to the adopted code of practice or, Appendix A6
of the CIRIA C580 publication “Embedded retaining walls –
guidance for economic design”
The total effective horizontal active and passive earth pressures
acting against the wall are then determined by :
p′a
(total)
= p′ a + u
and
p′p
(total)
= p ′p + u
where u is the pore water pressure.
4.9 Tension crack
At small depths in cohesive soils or when the soil possesses high
undrained cohesion, it may be found that the calculated active
pressure has a negative value. Although this implies that the soil is
in tension, the situation in fact represents zero pressure and the
depth over which it occurs is referred to as a tension crack. In any
cohesive soil, the theoretical depth to which a tension crack can
develop is given by the expression
depth = ( 2 x su - q) / γ
Chapter 4/15
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
where su is the undrained shear strength of the soil,
q is any applied surcharge,
and γ is the density of the soil.
When a tension crack is able to develop, careful consideration of
the water regime in the vicinity of the wall is needed to ensure that
appropriate design pressures are adopted. If the crack could fill
up with water to either the normal ground water level or the soil
surface then hydrostatic pressures should be adopted from the
appropriate elevation. If it is considered unlikely that ground water
could enter the crack it is recommended that a minimum effective
fluid pressure (MEFP) equivalent to that of a fluid with a density of
5kN/m3 is applied.
The fluid pressure, either hydrostatic or MEFP, should be applied
to the wall to the depth at which the calculated soil and water
pressures dominate.
Fig 4.9
Minimum total horizontal
stress = γwZ
(For cantilever walls and
where water is expected)
MEFP=5z
(where water is
not expected)
Total horizontal stress
4.10 Groundwater pressures
When considering the effects of water pressure for Ultimate Limit
State Design (ULS), the water pressure and seepage forces
assumed should be the most unfavourable values which may
occur in extreme or accidental circumstances over the wall’s
construction sequence and throughout its design life. An example
of an extreme/accidental event being a burst water main in close
proximity to the wall.
For Serviceability State Calculations (SLS) the water pressures
and seepage forces should be those that occur in ‘normal’
Chapter 4/16
Piling Handbook, 8th edition (revised 2008)
circumstances over the wall’s construction sequence and
throughout its design life. Extreme/accidental events such as a
burst water pipe may be excluded, unless the designer considers
that in reasonable circumstances such an event may occur.
4.11 Permanent structures
The critical design condition for permanent structures in fine silts,
normally and slightly over-consolidated clays, will usually be that
using total stress parameters, although a check with the
alternative effective values may be advisable.
The critical design condition for permanent structures in overconsolidated clays will usually be with effective stress parameters,
but a check using total values may be advisable.
4.12 Temporary structures
When the anticipated life of the structure is less than three
months, and when construction is in clay, it is usual to adopt total
stress parameters for the design. However, this assumption carries
significant risk and therefore the designer should, if possible,
ensure regular monitoring of the works to check that the design
assumptions are realised in practice. Where the designer has no
direct control over construction activities then it is advisable that
the designer also considers the use of long term, effective stress
parameters for the design. In any case, contingency measures
should also be on hand in case of any untoward changes during
the temporary phase.
An allowance in the design should also be made for softening of
the soil on the restraining side of the wall for the duration of the
temporary works. i.e. due to excavation disturbance and
dissipation of pore water pressures at excavation level. The value
of the undrained shear strength on the restraining side should be
assumed to be zero at excavation level rising to su at a depth of L,
where :
L = 0.5 m where there is no potential for groundwater recharge
either at excavation level or within the soil
L=
√ ( 12.c v .t)
where recharge occurs at excavation level but with
no recharge within the soil. cv is the coefficient of
consolidation and t is the time elapsed.
Temporary structures of greater than three months anticipated life
should be treated as permanent structures.
Chapter 4/17
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
4.13 Battered walls
The effect of batters up to 5° may be neglected.
4.14 Concentrated and linear surcharge
These are treated in a similar manner to superimposed loads
except that allowance should be made for dissipation of the load
at increasing depth.
There are various methods of allowing for this dissipation and the
following is suggested by Krey when designing for cohesionless soils.
The maximum increase in horizontal total stress is given by :
4 q . t a n 2 ( 4 5 ° – ø′/ 2 )
(σh max) =
where
2 + ( 1 + t a n 2( 4 5 – ø′ / 2 ) ) . x / z
q = magnitude of surcharge (kN/m2)
a = x.tan ø ′
c = x / tan(45° – ø ′ / 2 )
d = z / tan(45° – ø ′ / 2 )
Fig 4.14.1
Chapter 4/18
Piling Handbook, 8th edition (revised 2008)
4.15 Sloping ground surface
Approximate pressures can be obtained by assuming a horizontal
surface and increasing the pressures thus obtained by 5% for
each 5° inclination above the horizontal.
Alternatively an arbitrary horizontal ground surface, at some level
above that at which the sloping surface intersects the wall may be
assumed.
When dealing with cohesionless soils the following method may
be adopted.
pa at A = 0.Ka
p a a t B = γ . h 1. K a
p a a t C = γ . h 2. K a
Fig 4.15.1
4.16 Earth pressure calculation
In this section a set of design earth pressures for use in Ultimate
Limit State checks have been produced for the total stress and
effective stress condition. The method of calculation corresponds to
that discussed in paragraphs 4.6 to 4.8. i.e. using moderately
conservative soil parameters with Fs values of 1.2 applied to effective
stress parameters c′ and o/′ and an Fs of 1.5 on the total stress
parameter s u.
An assessment of the stress in the soil at any change of circumstance,
i.e. stratum boundary, water level, formation/excavation level etc is
carried out at for both sides of the wall.
For total stress analysis, cohesive strata are assumed to be
impervious and the bulk weight density should be used in
calculations.
Chapter 4/19
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
The earth pressure coefficients, Ka and Kp used for both total and
effective stress analyses are obtained from tables 4.8.1 and 4.8.2.
Values of Kac and Kpc for cohesive layers in the total stress analysis
are taken from table 4.7.1, assuming α = 0.50.
Table 4.16.1 - Total Stress Analysis
Values of K a , K a c , K p, K pc
Ka
Loose Fine Sand
0.317
Soft Clay
1.000
Sand and Gravel
0.229
Firm Clay
1.000
K ac
Kp
K pc
3.963
2.450
1.000
2.450
6.493
2.450
1.000
2.450
Table 4.16.2 - Effective Stress Analysis
Values of K a , K a c , K p, K pc
Ka
Loose Fine Sand
0.317
Soft Clay
0.494
Sand and Gravel
0.229
Firm Clay
0.444
K ac
Kp
K pc
3.963
1.406
2.193
2.962
6.493
1.333
2.512
3.170
* For the above earth pressure coefficients it is assumed that on
both the active and passive sides of the wall, wall/soil friction
δ = + 2 /3 ø′d
Chapter 4/20
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Fig 4.16.1 Total Stress Analysis Example
Earth and water pressures : Total stress analysis (short term)
Soil overburden including effects of water pressure and buoyancy : Active Side
Overburden at ground level
= 10.00 KN/m2
Overburden at -1.2m level in loose fine sand
= (14.70 x 1.20)+ 10.00
= 27.64 KN/m2
Overburden at -2.4m level in loose fine sand
= (9.29 x 1.20) + 27.64
= 38.79 KN/m2
Overburden at -2.4m level in soft clay
= 38.79 + (1.20 x 9.81)
= 50.56 KN/m2
Overburden at -6.1m level in soft clay
= (17.20 x 3.70) + 50.56
= 114.20 KN/m2
Overburden at -6.1m level in sand and gravel
= 114.20 - (4.90 x 9.81)
= 66.13 KN/m2
Overburden at -11.0m level in sand and gravel
= (10.79 x 4.90) + 66.13
= 119.00 KN/m2
Overburden at -11.0m level in firm clay
= 119.00 + (9.80 x 9.81)
= 215.14 KN/m2
Overburden at -16.0m level in firm clay
= (18.60 x 5.00) + 215.14
= 308.14 KN/m2
Soil overburden including effects of water pressure and buoyancy : Passive Side
Overburden at -7.9m level
=
0.00 KN/m2
Overburden at -11.0m level in sand and gravel
= (10.79 x 3.10)
= 33.45 KN/m2
Overburden at -11.0m level in firm clay
= 33.45 + (3.10 x 9.81)
= 63.86 KN/m2
Overburden at -16.0m level in firm clay
= (18.60 x 5.00) + 63.86
= 156.86 KN/m2
Chapter 4/21
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Earth pressures
Active side
pa at ground level
= 0.317 x 10
=
3.17 KN/m2
pa at -1.2m level in loose fine sand
= 0.317 x 27.64
=
8.76 KN/m2
pa at -2.4m level in loose fine sand
= (0.317 x 38.79) + 11.77
= 24.07 KN/m2
pa at -2.4m level in soft clay
= (1.00 x 50.56) - (2.45 x 25/1.5)
=
pa at -6.1m level in soft clay
= (1.00 x 114.20) - (2.45 x 25/1.5)
= 73.37 KN/m2
pa at -6.1m level in sand and gravel
= (0.229 x 66.13) + 48.07
= 63.21 KN/m2
pa at -11.0m level in sand and gravel
= (0.229 x 119.00) + 96.14
= 123.39 KN/m2
pa at -11.0m level in firm clay
= (1.00 x 215.14) - (2.45 x 65/1.5)
= 108.97 KN/m2
pa at -16.0m level in firm clay
= (1.00 x 308.14) - (2.45 x 65/1.5)
= 201.97 KN/m2
pp at -7.9m level
= 0 x 6.493
=
pp at -11.0m level in sand and gravel
= (6.493 x 33.45) + 30.41
= 247.60 KN/m2
pp at -11.0m level in firm clay
= (1.00 x 63.86) + (2.45 x 65/1.5)
= 170.03 KN/m2
pp at -16.0m level in firm clay
= (1.00 x 156.86) + (2.45 x 65/1.5)
= 263.03 KN/m2
9.73 KN/m2
Passive side
Chapter 4/22
0.00 KN/m2
Piling Handbook, 8th edition (revised 2008)
Fig 4.16.2 Total Stress Diagrams
Earth and water pressure
Chapter 4/23
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Fig 4.16.3 Effective Stress Analysis Example
Effective stress analysis (long term)
Soil overburden including effects of water pressure and buoyancy : Active side
Overburden at ground level
= 10.00 KN/m2
Overburden at -1.2m level in loose fine sand
= (14.70 x 1.20) + 10.00
= 27.64 KN/m2
Overburden at -2.4m level in loose fine sand
= (9.29 x 1.20) + 27.64
= 38.79 KN/m2
Overburden at -2.4m level in soft clay
Overburden at -6.1m level in soft clay
= 38.79 KN/m2
= (7.39 x 3.70) + 38.79
Overburden at -6.1m level in sand and gravel
Overburden at -11.0m level in sand and gravel
= 66.13 KN/m2
= (10.79 x 4.90)+ 66.13
Overburden at -11.0m level in firm clay
Overburden at -16.0m level in firm clay
= 66.13 KN/m2
= 119.00 KN/m2
= 119.00 KN/m2
= (8.79 x 5.00)+ 119.00
= 162.95 KN/m2
Soil overburden including effects of water pressure and buoyancy : Passive side
Overburden at -7.9m level
Overburden at -11.0m level in sand and gravel
=
= (10.79 x 3.10)
Overburden at -11.0m level in firm clay
Overburden at -16.0m level in firm clay
Chapter 4/24
0.00 KN/m2
= 33.45 KN/m2
= 33.45 KN/m2
= (8.79 x 5.00) + 33.45
= 77.40 KN/m2
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
Earth pressures
Active side
p′a at ground level
= 0.317 x 10
=
3.17 KN/m2
p′a at -1.2m level in loose fine sand
= 0.317 x 27.64
=
8.76 KN/m2
p′a at -2.4m level in loose fine sand
= (0.317 x 38.79) + 11.77
= 24.07 KN/m2
p′a at -2.4m level in soft clay
= (0.494 x 38.79) + 11.77
= 30.93 KN/m2
p′a at -6.1m level in soft clay
= (0.494 x 66.13) + 48.07
= 80.74 KN/m2
p′a at -6.1m level in sand and gravel
= (0.229 x 66.13) + 48.07
= 63.21 KN/m2
p′a at -11.0m level in sand and gravel
= (0.229 x 119.00) + 96.14
= 123.39 KN/m2
p′a at -11.0m level in firm clay
= (0.444 x 119.00) - (1.333 x 2/1.2) + 96.14
= 146.75 KN/m2
p′a at -16.0m level in firm clay
= (0.444 x 162.95) - (1.333 x 2/1.2) + 145.19
= 215.32 KN/m2
p′p at -7.9m level
= 0 x 6.493
=
p′p at -11.0m level in sand and gravel
= (6.493 x 33.45) + 30.41
= 247.60 KN/m2
p′p at -11.0m level in firm clay
= (2.512 x 33.45) + (3.170 x 2/1.2) + 30.41
= 119.72 KN/m2
p′p at -16.0m level in firm clay
= (2.512 x 77.40) + (3.170 x 2/1.2) + 79.46
= 279.17 KN/m2
Passive side
0.00 KN/m2
Chapter 4/25
Piling Handbook, 8th edition (revised 2008)
Fig 4.16.4 Effective Stress Diagrams
Earth and water pressure
Chapter 4/26
Piling Handbook, 8th edition (revised 2008)
Earth and water pressure
It is clear from the pressure diagrams, Figures 4.16.2 and 4.16.4,
that the active earth pressures generated in the soft/firm clays are
considerably greater for the effective stress condition than those
produced in the total stress analyses. Also on the passive side,
the pressures which provide stability in the effective stress
condition are significantly less than for the total stress condition.
Clearly in this case the most onerous condition is the effective
stress case which should be used for any permanent works
design. The earth pressures calculated for the short term condition
may be used for temporary construction, but designers should
always satisfy themselves that total stress conditions will exist
throughout the temporary phase. If in doubt designers should
always err on the side of caution and use the worst case earth
pressure values.
The methods by which earth pressure diagrams are used to
design the embedment depth and minimum structural
requirements of a sheet pile structure are illustrated in chapters 6
and 7.
Chapter 4/27
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
5
Design of sheet
pile structures
1
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
Contents
Page
1
5.1
Introduction
5.2
Types of wall
1
5.3
General considerations
3
5.4
Selection of design method
5
5.5
Factor of safety
5
5.6
Limit state designs
8
5.7
Free or fixed earth design
5.8
Dealing with water
10
Flow nets
11
Surcharge loading
11
5.10
Support location
11
5.11
Walls supported by more than one
level of struts or ties
12
5.11.1
Hinge method
12
5.11.2
Continuous beam method
12
5.12
Softened zone
13
5.13
Bending moment reduction
14
5.14
Calculating support forces
14
5.15
Structural design of wall
15
5.16
Selection of pile section
16
5.17
Design bending stresses
16
5.18
5.8.1
5.9
8
Checklist of design input parameters
17
5.18.1
ULS conditions
17
5.18.2
SLS conditions
17
Analysis of pressure diagrams
19
5.19
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
5.1 Introduction
A sheet pile retaining wall has a significant portion of its structure
embedded in the soil and a very complex soil/structure interaction
exists as the soil not only loads the upper parts of the wall but also
provides support to the embedded portion.
Current design methods for retaining walls do not provide a rigorous
theoretical analysis due to the complexity of the problem. The
methods that have been developed to overcome this, with the
exception of finite element modelling techniques, introduce empirical
or empirically based factors that enable an acceptable solution to
the problem to be found. As a result, no theoretically correct solution
can be achieved and a large number of different approaches to this
problem have been devised.
The design of a retaining structure using currently available
techniques requires the performance of two sets of calculations, one
to determine the geometry of the structure to achieve equilibrium
under the design conditions, the other to determine the structural
requirements of the wall to resist bending moments and shear forces
determined from the equilibrium calculations. The selected design
conditions should be sufficiently severe and varied so that all
reasonable situations which may occur during the life of the
structure are taken into account.
Designers should not overlook the possibility of global failure
resulting from deep-seated slip failure of the soil and ensure that the
slip plane passing through the pile toe is not critical. Similarly,
anchor walls should be located outside potential slip planes.
This chapter covers the fundamental issues involved in the design of
earth retaining structures and is therefore relevant for retaining walls
and cofferdams. Information of specific relevance to retaining wall
design is included in chapter 6 and to cofferdams in chapter 7.
5.2 Types of wall
Retaining walls can be divided into cantilever or supported types.
Cantilever walls are dependent solely upon penetration into the soil
for their support and clearly fixity of the toe is required to achieve
equilibrium of the forces acting on the structure. As fixity of the wall
toe requires longer and, in many cases, heavier piles to achieve the
necessary penetration into the soil, this type of wall can only be
economic for relatively low retained heights. It is also likely that
deformations will be large for a cantilever solution.
Variations in soil properties, retained height and water conditions
along a wall can have significant effects on the alignment of a
cantilever wall and care must be taken when designing them for
permanent structures, although provision of a capping beam will
often alleviate alignment problems.
Chapter 5/1
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
Fig 5.2
Supported walls, which can be either tied or strutted, achieve
stability by sharing the support to be provided between the soil
and the supporting member or members. In this situation the soil
conditions at the toe of the wall are not as critical to the overall
stability of the structure as in the case of a cantilever wall. The
provision of longitudinal walings to transfer the soil loadings into
ties or struts also caters for variations in displacement along the
structure.
The maximum height to which a cantilever wall can be considered
to be effective will generally be governed by the acceptable
deflection of the wall under load. This comment doesn’t just apply
to sheet pile walls where the relative flexibility of the wall is often
seen as a drawback because the overall deflection of the wall is a
combination of bending of the wall structure and movement in the
soil which will occur irrespective of the type of wall to be built.
However as a rough guide, it is unlikely that a cantilever wall will
be more cost effective than a tied or propped wall when the
retained height exceeds about 4.5 to 5 metres because the pile
section needed for an unpropped wall of that height will be both
long and heavy to resist the applied bending moments. Similarly a
wall supported by a single tie or prop will generally only be cost
effective up to a retained height in the order of 10 metres.
When more than one level of supports is used, wall stability
becomes a function of the support stiffness and the conventional
active/passive earth pressure distribution does not necessarily
apply.
Chapter 5/2
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
5.3 General considerations
An earth retaining structure must be designed to perform
adequately under two particular sets of conditions, those that can
be regarded as the worst that could conceivably occur during the
life of the structure and those that can be expected under normal
service conditions. These design cases represent the ultimate and
serviceability limit states respectively for the structure.
Ultimate limit states to be taken into account in design include
instability of the structure as a whole including the soil mass,
failure of the structure by bending or shear and excessive
deformation of the wall or soil to the extent that adjacent
structures or services are affected.
Where the mode of failure of the structure involves translation or
rotation, as would be expected in the case of a retaining wall, the
stable equilibrium of the wall relies on the mobilisation of shear
stresses within the soil. Full mobilisation of soil shear strength
results in limiting active and passive conditions and these can only
act simultaneously on the structure at the point of collapse, the
ultimate limit state.
Design for serviceability involves a consideration of the
deformation of the structure and movement of the ground to
ensure that acceptable limits are not exceeded. The deformations
of the ground which accompany full shear strength mobilisation
are large in comparison to those which occur in normal service
and as the forces on the structure and the forces from the retained
soil are inversely proportional to movement, the serviceability limit
state of displacement will often be the governing criterion for
equilibrium. Although it is impossible or impractical to directly
calculate displacements, serviceability requirements can generally
be achieved by limiting the magnitude of the mobilised soil
strength. This is achieved in practice by applying factors of safety
to the design parameters.
One aspect of design that is often overlooked by inexperienced
designers is the advantage to be gained by considering at an early
stage in the design process which section will be required for
installation as it may be necessary to provide a heavy section and
/ or a high quality of steel where it is anticipated that piles will
need to be driven to significant depth or where driving will be
hard. Piles that have been sized for onerous driving conditions will
generally have high bending resistance and this additional
capacity may permit one or more levels of support to be
eliminated with a consequent reduction in design effort.
The designer of a retaining wall must assess the design situations
to which the wall could be subjected during its lifetime and apply
these to the structure to analyse their effect.
Chapter 5/3
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
The design situations should include the following where
appropriate:
Applied loads and any combinations of loadings
Includes surcharges and externally applied loads on each side of
the wall.
The surcharge load acting on a wall will depend on its location and
intended usage. In the UK it is suggested that a minimum surcharge
of 10 kN/m2 is adopted on the retained side of the wall, but in other
European countries, a surcharge of 20 kN/m2 is recommended to
allow for the presence of plant or materials during construction. This
is discussed further in section 5.9.
Where very high levels of surcharge or concentrated loads occur,
e.g. ports and harbours, it is often more economical to carry them
on bearing piles which transfer them to a lower stratum where no
lateral pressure is exerted on the retaining structure.
Geometry of the problem
The basic retained height to be used in calculations will be the
difference in level between the highest anticipated ground level on
the active side of the wall and the lowest level on the passive. An
allowance for unplanned excavation in front of the wall of 10% of
the retained height of a cantilever or 10% of the distance below
the lowest support in a supported wall up to a maximum of 0.5m
should be included in the ultimate limit state calculations. It should
be noted that if excavation for pipes or cables in the passive zone
is likely then the trench depth is considered to be part of the basic
excavation depth and should not be part of the unplanned
excavation allowance. The unplanned excavation depth does not
apply to serviceability calculations.
Material characteristics
In permanent structures, the long-term performance of steel must
be considered and a heavier pile section than that determined by
structural analysis may be needed to take into account the longterm effects of corrosion.
Environmental effects
Variations in ground water levels, due to dewatering, flooding or
failure of drainage systems need to be taken into account in
design. Consider the effects of providing weep holes to prevent
the accumulation of ground water behind the wall; however these
must be designed to prevent clogging by any fines transported in
the flowing water. Scour, erosion and tree removal will all affect the
structure. Weathering, freezing and other effects of time and
environment on the material properties will also have an effect on
structural performance.
Mining subsidence
Consider the tolerance of the structure to deformation.
Chapter 5/4
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
Construction
Driving of sheet piles into dense soils may necessitate the
provision of a section larger than that needed to satisfy the
structural requirements. Driveability should be considered at an
early stage in the design process as the need to provide a
minimum section for driving may lead to a more efficient support
system and may also offset any additional thickness needed to
achieve the desired life expectancy for the structure.
5.4 Selection of design system
Modern computer software packages provide the engineer with
the opportunity to carry out a simple limit equilibrium design, a
more complex soil-structure interaction calculation or a
sophisticated finite element analysis. As the complexity of the
analysis method rises, the amount and complexity of data also
increases and the analysis method should therefore be selected to
suit the sophistication of the structure and to ensure that any
economies deriving from a more complex analysis can be realised.
When the structure is such that there will be little or no stress
redistribution, as can be expected for a cantilever wall, limit
equilibrium calculations and soil-structure interaction analyses are
likely to give similar wall embedment depths and wall bending
moments. For supported walls, where redistribution of stresses
may be expected, a soil structure interaction analysis will normally
provide a more economic design involving a shorter wall and
reduced bending moments.
5.5 Factor of safety
Many different methods of analysis have been developed to
calculate the embedment depth required to ensure stability in a
retaining structure. These methods are generally empirical and
based on the concept that the soil will attain active and passive
pressure conditions at the point of failure. The pressure diagrams
resulting from this ultimate condition are then used to determine
the length of pile required to achieve moment equilibrium.
However as this represents imminent failure of the wall, a factor of
safety is applied, to ensure that the soil stresses are limited to an
appropriate value and that the failure condition is not realised in
practice.
The factor of safety may be applied in a number of different ways:
1 application of a scale factor to increase the calculated depth of
embedment required for limiting equilibrium,
2 reduction of the theoretical soil strengths by application of an
appropriate factor,
3 application of an appropriate factor to increase the nett or
gross pressures acting on the structure.
Chapter 5/5
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
The magnitude of the factor or factors applied is dependent upon
the method of analysis used and reflects the confidence the
designer places in his choice of soil parameters for design and
the deformation limits to be applied to the structure.
Eurocode 7, which covers geotechnical design, adopts a limit
state philosophy which is also a feature of many of the National
Standards currently in use (ie BS8002). The traditional design
methods – developed through many years of use – apply a global
factor of safety to the calculated values to cover all unknowns and
the effect of its introduction is well understood by designers.
Limit state design is a more scientific approach as it applies
different factors to the various parameters affecting the wall
design (i.e. soil density, surcharges, loads etc.) to enhance
unfavourable (disturbing) loads and pressures and reduce
favourable (restoring) ones. In this way, the design parameters
that introduce the most uncertainty are subject to more onerous
factors. For example, the reduction factor applied to undrained
cohesion is larger than that applied to the angle of internal friction
for a soil.
Different factors are applied dependent upon the nature of the
analysis being carried out i.e. serviceability or ultimate limit state.
By adopting a partial factor design method, the factors of safety
are introduced when the soil parameters and applied loads are
determined and the pressure diagram already includes the
necessary factors. The designer will need to carry out calculations
to determine the length of pile that results in equilibrium of the
earth pressures i.e. a factor of safety of 1. Although it is the
intention of this publication to support the use of partial factor
design, for the sake of completeness, the brief paragraphs
following are included to illustrate how factors of safety were
applied in some of the more common wall design methods.
Gross pressure method
The factor of safety is applied to the gross passive pressure
diagram only. This approach can lead to an anomaly in undrained
conditions where Ka = Kp = 1 as, beyond a certain depth of
embedment, the calculated factor of safety decreases with
increasing length of wall. This situation results from the fact that
the bulk weight of the soil on the passive side, used to calculate
the earth pressures acting on the wall, is effectively reduced by
the factor of safety.
Nett pressure method
The method has been used by designers for many years and is
often referred to as the Piling Handbook method. The factor of
safety is applied to the nett passive pressure diagram derived by
subtracting the active earth and water pressure at a given level
from the passive earth and water pressure. The method tends to
Chapter 5/6
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
give higher factors of safety for a given geometry when compared
to other methods, but careful selection of conservative design
parameters, will give acceptable analysis results.
Revised method
Developed by Burland and Potts, the factor of safety is applied to
the moment of the nett available passive resistance. This is the
difference between the gross passive pressure and those
components of the active pressure that result from the weight of
soil below dredge level. In effect the factor of safety is applied to
the dead weight of soil below dredge level on both sides of the
wall. This method partially overcomes the anomaly in the gross
pressure method.
Factor on strength method
The strength parameters of the soil are reduced by an appropriate
factor in a method analogous to the calculation of embankment
stability. The effect is to increase Ka and decrease Kp, modifying
the pressure distribution relative to that used as a base in the
other described methods.
Chapter 5/7
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
5.6 Limit state designs
The design calculations prepared to demonstrate the ability of a
retaining wall to perform adequately under the design conditions
must be carried out with full knowledge of the purpose to which
the structure is to be put. In all cases, it is essential to design for
the collapse condition or Ultimate Limit State (ULS) and in some
situations it may also be appropriate to assess the performance of
the wall under normal operating conditions, the Serviceability Limit
State (SLS). SLS calculations should be carried out where wall
deflections and associated ground movements are of importance.
When a wall is dependent upon its support system for stability
and where it is foreseen that accidental loading could cause
damage or loss of part or all of that support system, the designer
should be able to demonstrate that progressive collapse of the
structure will not occur. An example of this is the effect that loss
of a tie rod may have on a wall design.
5.7 Free or fixed earth design
When designing an earth retaining structure, the designer may
choose to adopt either free and fixed earth conditions at the toe of
the wall. The difference between these two conditions lies in the
influence which the depth of embedment has on the deflected
shape of the wall.
Fig 5.7a Free earth support
A wall designed on free earth support principles can be
considered as a simply supported vertical beam, The wall is
embedded a sufficient distance into the soil to prevent translation,
but is able to rotate at the toe providing the wall with a pinned
Chapter 5/8
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
support. A prop or tie near the top of the wall provides the other
support. For a given set of conditions, the length of pile required is
minimised, but the bending moments are at a maximum.
Fig 5.7b Fixed earth support
Kp
Ka
Kp
Ka
Deflected shape
Earth pressure distribution
Kp
Ka
Kp
do
Ka
Idealised earth pressure
distribution
Resultant, R
Simplified earth pressure
distribution.
A wall designed on fixed earth principles acts as a propped
vertical cantilever. Increased embedment at the foot of the wall
prevents both translation and rotation and fixity is assumed. Once
again a tie or prop provides the upper support reaction. The effect
of toe fixity is to create a fixed end moment in the wall, reducing
the maximum bending moment for a given set of conditions but at
the expense of increased pile length. The assumption of fixed
earth conditions is fundamental to the design of a cantilever wall
where all the support is provided by fixity in the soil.
When a retaining wall is designed using the assumption of fixed
earth support, provided that the wall is adequately propped and
capable of resisting the applied bending moments and shear
forces, no failure mechanism relevant to an overall stability check
exists. However empirical methods have been developed to
Chapter 5/9
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
enable design calculations to be carried out, an example of which
is given in chapter 6.
Designers must be careful when selecting the design approach to
adopt. For example, walls installed in soft cohesive soils, may not
generate sufficient pressure to achieve fixity and in those soils it is
recommended that free earth conditions are assumed. Fixed earth
conditions may be appropriate where the embedment depth of the
wall is taken deeper than that required to satisfy lateral stability,
i.e. to provide an effective groundwater cut-off or adequate vertical
load bearing capacity. However, where driving to the required depth
may be problematic, assumption of free earth support conditions will
minimise the length of pile to be driven and ensure that the theoretical
bending moment is not reduced by the assumption of fixity.
When designing a wall involving a significant retained height and
multiple levels of support, the overall pile length will often be
sufficient to allow the designer to adopt fixed earth conditions for
the early excavation stages and take advantage of reduced
bending moment requirements.
The design methods used to determine the pile length required
for both free and fixed earth support conditions do not apply if
the support is provided below the mid point of the retained height
as the assumptions made in the analysis models will not be valid.
5.8 Dealing with water
The water pressure conditions adopted in retaining wall design
should be the most onerous that can be possibly imagined as the
effect of water pressures on design calculations is very significant.
When an analysis is being carried out assuming that drained
conditions exist, the effect of flow beneath the toes of the sheet
pile wall is to increase the active pressures on the wall and
decrease the passive pressures, both of which have a de-stabilising
effect on the wall.
Water pressures to adopt when tension cracks develop in cohesive
soils are covered in section 4.9.
In order to reduce the effect of large water pressures resulting from
a difference in water level on each side of a retaining structure, the
designer may provide weep holes through the wall preventing an
accumulation of ground water. These will generally be located at
the bottom of the exposed section of wall to maximise their effect
as a means of reducing water levels. It should be noted however
that weep holes are only fully effective when free drainage is
possible and they should be designed in such a way that any roots,
stones or fine material transported by the flow of ground water will
not cause them to become clogged. In cohesive soils, weep holes
are ineffective in the relief of water pressure behind the wall.
Chapter 5/10
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
5.8.1 Flow nets
The preparation of a flow net can be a useful design tool when
assessing the effect of water on a design situation, as it not only
allows the engineer to calculate the water pressures in a particular
situation, but also provides a visual representation of the flow
regime in the soil. An illustration of how a flow net is constructed
is included in chapter 7.
5.9 Surcharge loading
To allow for the presence of plant and equipment around the
edge of the excavation during construction, it is recommended
that a minimum surcharge load is applied to the surface of the
retained ground. The magnitude of the surcharge is dependent
upon the size of plant involved and the expected activities. As
plant is increasing in size and weight, selection of too low a
surcharge may restrict the type of plant that can be used and it is
now common practice in Europe to adopt a minimum surcharge
of 20 kPa.
In UK, the minimum suggested surcharge is 10 kPa but designers
are warned that this should be increased (locally or globally) if
heavy plant is to be located adjacent to the cofferdam or if
excavated spoil or construction materials are to be stacked close
to the pile wall – a 1m height of spoil will result in a surcharge
load in the order of 20 kPa. However, if the wall is retaining less
than 3 m height the UK codes allow the designer to reduce the
surcharge load provided he /she is confident that a minimum
surcharge of 10 kPa will not apply during the life of the structure.
5.10 Support location
The location of supports to a retaining structure has a critical
bearing on the structural requirements of the wall itself. As has
been mentioned in the preceding sections, consideration of the
wall as either fixed or free in terms of its mode of operation
directly affects the bending moments, shear forces and support
reactions acting on the wall.
Similarly, the position at which supports are assumed to act will
affect the magnitude of bending moments and shear forces in the
wall itself and consequently the support reaction required for
stability.
When unusual support locations are provided, the conventional
methods of analysis do not apply and consideration must be
given to the mode or modes of failure that may occur. Walls
involving low level props are discussed in section 6.3.1.
Chapter 5/11
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
5.11 Walls supported by more than one level of struts or ties
When more than one level of support is provided to a wall the
potential mode of failure is significantly different to that assumed
for a wall with a single support provided that the supports are not
close enough together to act as a single support. With multiple
levels of support, the wall will not fail by rotation in the
conventional manner – failure will be as a result of collapse of the
support system or excessive bending of the piles. Consequently,
provided that the wall and supports are sufficiently strong to resist
the worst credible loading conditions, failure of the structure
cannot occur.
To assess the bending moments and reaction forces in a multipropped wall, a number of analysis methods have been
developed. Unfortunately, the structure is statically indeterminate
and a number of assumptions need to be made to enable the
structure to be analysed.
5.11.1 Hinge method
This method allows the structure to be analysed at successive
stages of construction and the assumption is made that a hinge
occurs at each support position except the first. The spans
between the supports are considered as simply supported beams
loaded with earth and water pressures and the span between the
lowest support and the excavation level is designed as a single
propped wall with the appropriate earth and water pressures
applied. Prop loads calculated using this method include the
respective load from adjacent spans.
The analysis of structures using this method is carried out on a
stage-by-stage basis with excavation being carried out to
sufficient depth to enable the next level of support to be installed.
It is therefore possible that the support loads and bending
moments calculated for a given stage of excavation are exceeded
by those from a previous stage and it is important that the highest
values of calculated support force and bending moment are used
for design purposes.
5.11.2 Continuous beam method
The wall is assumed to act as a vertical beam subjected to a
pressure distribution with reactions at support points. The
bottom of the beam is also assumed to be supported below
excavation level by a soil reaction at the point at which the nett
active pressure on the wall falls below zero. Mobilised earth
pressures are assumed to act on the wall, the magnitude of
these pressures being dependent upon a factor governed by the
Chapter 5/12
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
permissible movements of the wall being designed. The
minimum recommended mobilised earth pressure is however 1.3
times that resulting from the use of ka to determine soil
pressures on the wall.
Each support is modelled either as rigid or as a spring,
depending on its compressibility. The displacement at a rigid
support is zero, whereas in a spring it is proportional to the force
carried by the spring.
The hypothetical soil support is modelled in one of three ways.
If the nett pressure (active pressure – passive pressure at a given
depth) does not fall to zero anywhere along the wall, the
hypothetical soil support is ignored and the embedded portion of
the wall is treated as if it were a cantilever. This situation is likely
to occur if there is only a short depth of embedment or the nett
pressures are particularly large. The applied load in this case is
carried entirely by the props.
If the nett pressure does fall to zero along the length of the wall,
the hypothetical soil support is considered as a rigid prop. This
situation is likely to occur if there is a large depth of embedment
or the nett pressures are particularly small. The applied load in
this case is shared by the props and the soil. The force carried
by the soil is equal to the jump in shear force that occurs at the
hypothetical soil support. Under this assumption it is essential to
check that the force assumed to be provided by the hypothetical
soil support is not greater than the available soil resistance
below that support. If it is greater, the following method should
be applied.
If the nett pressure falls to zero, but the available soil resistance
below the point at which that occurs is less than that required by
the rigid soil prop a finite soil reaction equal in magnitude to the
available soil resistance should be adopted in subsequent
calculations. This situation is likely to occur if there is a moderate
depth of embedment. The applied load in this case is shared by
the props and the soil. The force carried by the soil is equal to the
change in shear force that occurs at the hypothetical soil support.
5.12 Softened zone
Where soft cohesive soils are exposed at dredge or excavation
level it is advisable when calculating passive pressures to assume
that the cohesion increases linearly from zero to the design
cohesion value over a finite depth of passive soil. This is
discussed in more detail in 4.12.
Chapter 5/13
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
5.13 Bending moment reduction
The simplifying assumption made in design calculations
concerning the linear increase in active and passive pressures in a
material does not take into account the interaction between the
soil and the structure. Studies have shown that this can have a
significant effect on the distribution of earth pressures and
consequent bending moments and shear forces on a structure.
The reduction in calculated bending moments is a function of the
soil type and the flexibility of the wall in comparison to the
supported soil. When a supported, flexible wall deflects, a
movement away from the soil occurs between the support
position and the embedded portion of the wall. This effect often
leads to a form of arching within the supported soil mass which
allows the soil to maximise its own internal support capabilities
effectively reducing the pressures applied to the wall. For a
relatively flexible structure, such as an anchored sheet pile wall,
the effect of wall deformation will be to increase the pressures
acting above the anchor level, as the wall is moving back into the
soil using the support as a pivot, and reduce the pressures on the
wall below this level where the biggest deflections occur.
The result of a redistribution of pressures is therefore a reduction
in the maximum bending moment on a wall, but an increase in
support reaction. Support loads calculated by a limit equilibrium
analysis are generally lower than those resulting from soil structure
interaction
Redistribution should not be considered for cantilever walls or
where the structure is likely to be subjected to vibrational or large
impact forces that could destroy the soil 'arch'. Similarly, if the
support system is likely to yield or movement of the wall toe is
expected, moment reduction should not be applied. Where
stratified soils exist, moment reduction should be viewed with
caution since soil arching is less likely to occur in soils of varying
strength.
The beneficial effects of soil arching on wall bending moment are
automatically taken into account in analysis packages based on
soil-structure interaction.
5.14 Calculating support forces
Previous editions of the Piling Handbook have recommended that
the calculated reaction force be increased by 25% to ensure that
support systems were not under-designed in the event that
arching and stress redistribution behind the wall occurred. This
additional load was included to take into account the fact that
limit equilibrium methods of analysis would not automatically allow
for soil structure interaction. When a soil structure interaction
Chapter 5/14
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
analysis is undertaken, load redistribution is automatic and there is
no need to increase the calculated loads.
It is recommended that support loads are calculated for both the
serviceability limit state and the ultimate limit state and a
distinction should be made between limit equilibrium and soil
structure interaction analyses. The recommendation is that loads
calculated using limit equilibrium methods should be increased by
85% and that the ULS support load should be the greater of the
SLS prop load x 1.35 or the value derived from the ULS
calculation.
Although this may seem to be a large increase, the original Piling
Handbook approach to sizing of tie rods involved calculation of
the tie load under what were effectively service conditions and
application of an additional 25% for arching. The resultant load
was then used in conjunction with a maximum steel stress of 0.5f y
to determine the minimum steel area and hence the tie rod size.
This combination provided a load factor of 2.5 when compared to
fy and the proposed factors result in an effective factor of 1.85 x
1.35 = 2.4975.
5.15 Structural design of the wall
Traditionally the structural design of steel piling, walings, struts,
and tie rods based on loads calculated using the limit equilibrium
approach would involve the introduction of a permissible design
steel stress. This was almost universally taken to be about 2/3 of
the yield stress of the steel. The design method also allowed
designers to adopt a small increase in the permissible stress if the
work was designated as temporary.
Table 5.15
Class of Work
Steel grade to EN 10248
S270GP
S355GP
N/mm2
N/mm2
Permanent
180
230
Temporary
200
260
The values in the table above can be used in conjunction with
bending moments calculated using unfactored input parameters which equates to the serviceability limit state.
However when design calculations are based on a limit state
approach, factors given in an appropriate structural design code
(ie EC3:part5 for piling, EC3:part1 for the other structural
elements) should be adopted. For example, in UK, it is
recommended that an additional factor should be applied to
bending moments derived from worst credible earth and groundChapter 5/15
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
water loads. These factored loads are then used with the yield
strength of the steel multiplied by a material factor. In the UK this
material factor is set to 1.0 at the time of going to press.
5.16 Selection of pile section
The absolute minimum sheet pile section required for the retaining
wall is that obtained from consideration of the bending moments
derived by calculation for the particular case in question. However,
it is also necessary to consider installation of the piles when
determining the section to be adopted as hard driving conditions
may require a heavier section to prevent buckling during
installation. This aspect is covered in more detail in Chapter 11.
Furthermore, the requirements with respect to the effective life of
the retaining wall will also need to be assessed. The effect of
corrosion on the steel piles is to reduce the section strength and
the design must ensure that the section selected will be able to
resist the applied bending moments at the end of the specified life
span without buckling or exceeding design stresses. In many
instances the need for a heavy section for driving automatically
introduces some if not all of the additional strength needed for
durability.
5.17 Design bending stresses
The Limit Equilibrium method of analysis enabled the designer to
assess the bending moments in the wall under working
conditions. To limit the stresses in the structure and thereby
control deflections, a factor of safety of 1.5 was applied to the
yield strength of the steel when calculating the minimum section
size required for the given conditions. Under these rules, normal
design conditions would result in a structure where the elements
were operating at a stress comfortably within their elastic capacity.
Corrosion activity reduces the section properties of the sheet pile
wall and, assuming that the bending moments in the wall do not
change, this has the effect of increasing the stress in the steel.
Clearly the upper limit on corrosion loss is defined by the point at
which the steel stress reaches yield and this was used traditionally
as a means of defining the effective life of a sheet pile structure. It
must not be overlooked that, while effective as a design method,
this approach created the condition where the factor of safety
against material failure was reducing with time.
It should be noted that when designing a wall using limit
equilibrium methods, it was possible for the designer to adopt a
different steel stress for permanent and temporary works on the
assumption that temporary works would not be subject to
corrosion conditions. Similarly, it was also possible to allow
Chapter 5/16
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
stresses in the steel to exceed the limit for temporary works for
conditions of short duration encountered during the construction
period – this was often referred to as the short term, temporary
condition.
The ability to flex the design stresses is not available under the
limit state system as the design stress in the steel is already
based on the yield strength.
5.18 Checklist of design input parameters
5.18.1 Ultimate Limit State (ULS) conditions
The designer should assess all construction and in-service
situations and design for the most onerous.
Soil design parameters
Factored soil design parameters should be used to derive earth
pressure coefficients for use in ULS calculations (see chapter 4).
Groundwater pressures
The worst credible groundwater pressures at each stage of the
construction sequence and throughout the wall’s design life
should be adopted.
Loads
The ULS design should be carried out using the worst credible
combination of loadings excluding extreme or accidental events.
It is recommended that a minimum surcharge load is applied to
the surface of the retained ground as discussed in 5.9.
Unplanned excavation
The ULS design condition should include an allowance for
unplanned excavation as outlined in 5.3.
Softened zone
If an allowance is to be made for softening of the passive soil in a
total stress analysis it should be applied beneath the unplanned
excavation level (see 5.12).
5.18.2 Serviceability Limit State (SLS) conditions
Soil design parameters
Unfactored soil design parameters should be used to derive earth
pressure coefficients for use in SLS calculations (see chapter 4).
Groundwater pressures
These should be the most unfavourable values which could occur
under normal circumstances during any construction stage or in
service. Extreme events such as a burst water main near the wall
may be excluded, unless the designer considers that under
normal circumstances this can be reasonably included.
Chapter 5/17
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
Loads
The loadings considered should be those that the designer
considers may apply under normal circumstances. Extreme or
accidental events should be excluded.
It is recommended that a minimum surcharge load is applied to
the surface of the retained ground, as discussed in 5.9.
Unplanned excavation
No allowance should be made for unplanned excavation below
the formation level expected in normal circumstances. However,
the expected formation level should take into account any
temporary excavation for services, if these can be reasonably
expected, and if appropriate any allowance for the excavation
tolerance.
Softened zone
If an allowance is to be made for softening of the passive soil in a
total stress analysis it should be applied beneath the unplanned
excavation level.
Chapter 5/18
Piling Handbook, 8th edition (revised 2008)
Design of sheet pile structures
5.19 Analysis of pressure diagrams
When creating a pressure diagram to work with, it is essential that
the pressure conditions are calculated at every change of state of
the problem i.e. strata boundaries, water tables, excavation depth
etc.. However when calculations involve a support, it is often very
convenient to include a pressure calculation at this level.
When taking moments of pressures about a given position, the
diagram can be broken down in different ways to produce a series
of sensible units.
It will be noted that in the situation where the pressure diagram is
divided into rectangles and triangles, care must be taken to
introduce the 1/2 factor for areas of triangles and either 1/3, 2/3 or
1/2 when assessing moments of areas about a point.
Fig 5.19 Analysis of pressure diagrams
When divided only into triangles, the 1/2 factor in the area
calculation appears everywhere and the moment factor will be 1/3
or 2/3.
Chapter 5/19
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
6
Retaining
walls
1
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Contents
Page
6.1
Introduction
1
6.2
Design activities for simple retaining walls
1
Pressure distributions
2
6.3.1
6.3
Low propped walls
3
6.3.2
Relieving platforms
4
6.4
Wall deflections
5
6.5
Anchorage systems
6
6.5.1
Location
6
6.5.2
Design of anchorages
6
6.5.3
Balanced anchorages
9
6.5.4
Cantilever anchorages
10
6.5.5
Grouted anchors
10
Walings
10
6.6
6.6.1
Design of walings
12
6.6.2
Ultimate bending capacity of parallel flange
channel walings.
13
Tie Rods
14
6.7.1
6.7
Tie rod fittings
16
6.7.2
Tie bar corrosion protection
17
6.7.3
Plates and washers
18
6.7.4
Special fittings
18
6.7.5
Site assembly
19
6.8
Example calculations
20
6.8.1
Cantilever retaining wall
20
6.8.2
Tied wall with free earth support
24
6.8.3
Tied wall with fixed earth support
27
6.8.4
Deadman anchorage
31
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.1 Introduction
The design requirements that apply to any sheet pile structure are
included in Chapter 5. This chapter is given to highlight
information of particular relevance to the design of retaining walls.
6.2 Design activities for simple retaining walls
The following is a checklist of the activities needed to design a
simple retaining wall structure.
The sequence does not include any actions in respect of
calculations to confirm that progressive collapse will not occur.
SLS calculations should be carried out where wall deflections and
associated ground movements are of importance or if you wish to
adopt an allowable stress approach to the wall design.
Should the wall be subject to vertical loading, an additional
calculation to verify vertical equilibrium will be needed – this may
affect the design wall length determined in step 2 below and
subsequent stages will need to take any additional wall length into
account.
1
Determine soil parameters, groundwater pressures, load case
combinations and design geometry appropriate for ultimate
limit state (ULS) calculations.
2
Carry out collapse (ULS) calculations using limit equilibrium
methods or soil-structure interaction analysis and determine
the design wall depth
3
Carry out ULS limit equilibrium or soil-structure interaction
analysis to determine wall bending moment, shear force and
prop load.
Note: If SLS assessment is not required, steps 4 to 7 may be
omitted.
4
Determine soil parameters, groundwater pressures, load case
combinations, and design geometry appropriate to SLS
calculations. This step may be omitted if SLS calculations are
not required.
5
For the design wall depth, carry out SLS calculations using
limit equilibrium methods or soil-structure interaction analysis
to determine SLS load effects (wall bending moment, shear
force and prop or anchor loads). This step may be omitted if
SLS calculations are not required.
6
Determine wall deflections and ground movements from the
SLS soil-structure interaction analysis (if undertaken) and
empirical correlations with comparable case history data. This
step may be omitted if wall deflections and ground
movements are not of importance.
Chapter 6/1
Piling Handbook, 8th edition (revised 2008)
Retaining walls
7
Check that the SLS load effects, wall deflections and ground
movements determined in step 6 comply with criteria (ie
check compliance with allowable stress criteria for steel sheet
pile walls, if appropriate).
8
Determine ULS bending moments (BM) and shear force (SF)
appropriate for the structural design of the wall as the greater
of: BM and SF from step 3 or 1.35 times the BM and SF
values determined from step 5 (if undertaken)
To calculate the section modulus required using a limit state code,
it may be necessary to apply a further factor to the calculated
bending moments. In UK this factor is 1.2 for design to BS5950.
The calculation of the SLS wall bending moment, shear force and
prop or anchor load (if applicable) requires consideration of the
pressures acting on the wall when it is in limiting equilibrium
(Fs = 1.0). The wall under ULS conditions will have a deeper
embedment corresponding to Fs > 1.0.
The entire embedded depth of the wall should be considered when
calculating the groundwater seepage pressure in the SLS condition.
6.3 Pressure distributions
The pressure diagram most frequently adopted as the starting point
for retaining wall design involves a generally triangular distribution of
pressure based on the assumption that the wall moves away from
the active soil and towards the passive. This simple diagram is ideal
for hand calculations and generally results in a conservative solution.
The simple triangular pressure distribution can be modified – this
normally requires a computer program - to include the effects of
wall movement. The resultant pressure distribution will generally
involve a pressure increase at points on the wall where the
movement is small (ie supports) and a reduction due to arching
where the movement is large.
The pressure diagram can be further modified if the effects of
soil/pile interaction are taken into account. Once again a
sophisticated computer package is required for this and the effect is
generally a reduction in active pressure and an increase in passive.
The pressure diagram may also need to be amended if the wall
support is provided at a relatively low level - as may be the case
when a base slab is cast up against a cantilever retaining wall. In
this situation, the slab will act as the pivot point and the failure
mode may then involve forward movement of the upper part of the
wall and a backward movement of the lower portion of the pile.
This will cause the active and passive pressure zones to change
sides below the pivot, the effect of which needs to be included
in the design assessment. This is covered in more detail in
section 6.3.1.
Chapter 6/2
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Similarly the inclusion of a relieving platform behind the wall will
allow active pressures to be reduced below the platform level on
the assumption that any surcharge and the weight of soil are
supported by the slab and distributed into the support system for
the slab as vertical loads. The intention is that this will result in
lower earth pressures and smaller bending moment in the wall.
6.3.1 Low propped walls
Research at Imperial College, London has shown that the earth
pressures acting on retaining walls that are restrained with a single
level of supports at or near excavation level, are different to those
assumed in conventional limit equilibrium calculations. Conventional
calculations assume that the mode of failure for a retaining
structure supported at or near the top will be in the form of a
forward rotation of the pile toe and the pressure distribution at
failure is based on this assumption. The failure mode assumed for a
low propped wall is that the pile will move away from the soil at the
top in a similar manner to a cantilever and the pile will move back
into the soil below the support level. This will result in the
generation of passive pressures on the back of the wall and active
pressures on the front.
To design a wall incorporating a low prop, there are two
fundamental requirements that must be satisfied for the calculation
method to be correct. Firstly, the prop must be sufficiently rigid to
act as a pivot and prevent any forward movement of the wall and
secondly, the sheet piles forming the wall must be capable of
resisting the bending moments induced at the prop level to ensure
that rotation of the pile occurs rather than buckling.
Fig 6.3.1 Pressure distribution on a low propped wall
Chapter 6/3
Piling Handbook, 8th edition (revised 2008)
Retaining walls
The design rules resulting from the Imperial College work suggest
that the earth pressures below the support should be calculated
assuming that active pressures apply at and above the prop
position with full passive pressure at the toe of the pile; the
change from one to the other being linear.
The support may be considered to be at low level if the depth to
the support exceeds two thirds of the retained height of the
excavation.
The operation of a low propped wall is very complex and it is
recommended that the design of such a structure is carried out
using soil structure interaction.
6.3.2 Relieving platforms
When the depth of soil to be retained and/or the applied
surcharge loading (e.g. from heavy wharf cranes) is excessive, soil
pressures may be reduced by the use of a relieving platform.
The relieving platform is constructed such that it will support the
surcharge loads and the upper portion of the retained soil, these
loads being transferred to lower strata where there will be no
effect on the pressures acting on the wall. Bearing piles, which
support the platform and transfer the loads into the soil at depth,
may also be designed to provide an anchorage to the wall.
Fig 6.3.2 Relieving platforms
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Piling Handbook, 8th edition (revised 2008)
Retaining walls
The platform can be supported in part by the main sheet pile wall
and if the vertical loading becomes excessive, box or high
modulus piles may be introduced into the wall at appropriate
intervals to carry this load. Alternatively, bearing piles may be
provided immediately behind the wall.
The relieving platform must be designed such that it will intersect
the plane of rupture from the soil above and behind the platform
preventing any load from that soil acting on the wall. The main
sheet piles may extend up to ground level or be curtailed at
platform level with a concrete retaining wall being provided above
that level; the concrete wall must be designed to derive its
stability from the platform.
6.4 Wall deflections
The total deflection exhibited by a retaining wall comprises a
component based on the deflection of the section as a result of
the applied loads and a component based on compression of the
soil as the active/passive pressure regime is established. This
latter portion will apply irrespective of the material from which the
wall is formed as the magnitude of the movement is a function of
the soil properties rather than those of the wall. When assessing
the suitability of a particular form of wall for a given situation, the
engineer should consider what wall deflection is acceptable for
the environment in which the structure is to operate. For example
the deflection criteria may not need to be as onerous for a wall in
a rural setting compared to one in a congested inner city area.
It is often the case that the deflection for a flexible wall, for a given
set of conditions, is not substantially larger than that of a stiff wall.
It must not be overlooked however that it is often settlement of
the soil immediately behind the retaining wall that is the problem
to adjacent structures rather than the horizontal movement of the
wall itself.
A number of researchers have investigated the deflection of
retaining walls and it has been shown that the deflection of any
retaining wall is a function of the global system stiffness (Clough
et al, 1989) which is determined with the wall construction and the
propping arrangements in mind. This leads to the fact that the
expected deflection of a flexible wall with more props will be
similar to that of a stiff wall with fewer props.
Although deflection is probably considered to be a negative
feature of sheet piling construction, when the effects of flexibility
of the retaining structure are taken into account in the design
process, soil arching and stress redistribution will occur often
resulting in a significant reduction in the required bending moment
capacity when compared to a stiff wall. Hence in situations where
extra deflection can be accommodated, the reduced wall strength
demand means that a smaller pile section can be adopted
Chapter 6/5
Piling Handbook, 8th edition (revised 2008)
Retaining walls
allowing costs to be optimised and the wall footprint to be
minimised.
The deflection of the structure is not taken into account in a limit
equilibrium analysis and consequently a separate assessment of
the anticipated wall deflections is needed when wall movement is
important. The selection of appropriate soil parameters will
generally ensure that in-service stresses in the soils are not high
enough to result in large movements. It is suggested that adoption
of design effective stress parameters based on the lesser of the
representative critical state strength or representative peak
strength divided by a mobilisation factor of 1.2 will limit in service
displacements to 0.5% of the wall height if the soil is medium
dense or firm. In the case of total stress designs this limit on
movement will be achieved if the representative undrained
strength is divided by a mobilisation factor of at least 1.5.
Empirical methods have been developed to assess wall deflection
(Clough and O’Rourke, 1990) but when movements are critical, it
is recommended that an analysis involving soil structure
interaction is undertaken as the expected movements will be
incorporated into the analysis amending the soil pressures
accordingly.
6.5 Anchorage systems
6.5.1 Location
For an anchorage system to be effective it must be located
outside the potential active failure zone developed behind a sheet
pile wall – outside line DE in figure 6.5.1a. Its capacity is also
impaired if it is located in unstable ground or if the active failure
zone prevents the development of full passive resistance of the
system.
If the anchorage is located between CA and DE, only partial
resistance is developed due to the intersection of the active and
passive failure wedges. However the theoretical reduction in
anchor capacity may be determined analytically.
In cohesive soils, the correct position for the anchorage is outside
the critical slip circle and at sufficient distance behind the wall to
develop a shear resistance equal to the ultimate capacity of the
anchorage.
6.5.2 Design of anchorages
Anchorages of this type can be formed as discrete units or as a
continuous wall and they should be positioned such that the
passive failure wedge from the toe of the anchor wall does not
coincide with the active failure zone behind the main wall as
illustrated in Fig. 6.5.1a.
Chapter 6/6
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Fig 6.5.1a Location of anchorages
The net passive resistance to be obtained from the soil (passive
minus active) is calculated as for the retaining structure using the
worst conceivable combination of circumstances. Wall friction
should only be taken into account when deriving the earth pressure
Fig 6.5.1b Development of anchor resistance in cohesive soils
Chapter 6/7
Piling Handbook, 8th edition (revised 2008)
Retaining walls
coefficients if the designer is confident that it can be realised under
all loading conditions – the conservative approach is to ignore it.
However, the effect of variations in the ground water level on soil
strength properties and the application of surcharge loading to the
active side of the anchorage only should be included to maximise
the disturbing loads and minimise the restoring loads.
The anchorage system should be designed to provide sufficient
resistance to movement under serviceability limit state conditions
and sufficient resistance to satisfy ultimate limit state loads in the tie
rods.
In a similar manner to the design of the main wall, the anchorage
system may be assessed on the basis of serviceability and ultimate
limit states – see Section 6.2 for situations where an SLS analysis is
essential. The serviceability support load is taken as the actual
value derived from a soil structure interaction based analysis or that
derived from limit equilibrium based calculations multiplied by a
factor of 1.85 and this load is used in the structural design of the
anchor components. This factor is used to take into account the
fact that the anchorage is a critical part of the stability system for
the wall and that loads derived from a limit equilibrium analysis can
be significantly lower than those predicted by methods that adopt
soil structure interaction.
Similarly, the ultimate limit state load is the greater of that derived
for serviceability multiplied by 1.35 or that resulting from an analysis
of ULS conditions. Once again the 1.85 factor is applied to the ULS
loads derived using limit equilibrium analysis.
Design of the anchorage components, to established structural
codes will generally require the support loads generated as
indicated above, to be further multiplied by a factor to give ultimate
design loads.
In certain situations, progressive collapse of the structure may be
a consequence of an extreme condition ie failure of a tie rod and
under such circumstances, the designer should carry out a risk
assessment and if necessary avoid the possibility by changing the
design or applying controls to the construction activities.
If necessary calculations may be required to demonstrate that
progressive collapse will not occur.
These calculations should be carried out using unfactored soil
parameters and normal water levels, the resultant bending
moments and support forces being treated as ultimate loads.
With this robust construction requirement in mind, the
effectiveness of discrete anchorages needs to be given careful
consideration. The waling to the main wall will need to be
checked to ensure that it will not collapse if the span between
supports doubles following the loss of a tie rod. The ties on either
Chapter 6/8
Piling Handbook, 8th edition (revised 2008)
Retaining walls
side of the one that has failed will share the load from the missing
tie and, dependent upon the magnitude of the loads involved, the
resistance to be provided by each discrete anchorage may need
to increase to resist the loading. If the tie rods are attached to a
continuous anchorage, the total area of the anchorage will not
change but the walings will need to be strong enough to provide
the necessary support over a double span.
An example of anchorage design is included at the end of this
chapter.
6.5.3 Balanced anchorages
The design of balanced anchorages assumes that the resistance
afforded increases with depth below the ground surface giving a
triangular pressure distribution. The top of the anchorage is
assumed to be at a depth below the ground surface equal to 1/3
of the overall depth to its toe. The tie rod or tendon is placed
such that it connects with the anchorage at 2/3 of the overall
depth to the toe (on the centre line of the anchorage element).
This arrangement ensures that the tie rod force passes through
the centre of passive resistance.
The entire passive wedge developed in front of the anchorage,
including that above the top of the deadman unit, is effective in
providing resistance.
When the design is based on the provision of discrete anchorage
units, an additional force equal to that required to shear the
wedge of soil in front of the anchorage from adjacent soil at each
side can be added to the passive resistance to give the total
anchorage resistance.
The additional resistance resulting from shearing of the soil is
calculated using the following equations;
and
Cohesionless soils:
Ps= 1/3 γ d3 Ka tan(45+φ/2) tanφ
Cohesive soils
Ps= su d2
where Ps is the total shear resistance on both sides
of the wedge
d is the depth to the toe of the anchorage
su is the undrained cohesion of the soil.
In the case of an anchorage in cohesive soil, the top metre of soil
should be ignored if tension cracks are likely to develop parallel to
the tie rods.
The maximum resistance that can be developed in the soil is that
resulting from adoption of a continuous anchorage so it is essential
that a check is made to ensure that the resistance provided by a
series of discrete anchorages does not exceed this figure.
Chapter 6/9
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.5.4 Cantilever anchorages
Cantilever anchorages may be considered where good soil is
overlain by a layer of poor material. This type of anchorage can be
designed in the same manner as a cantilever wall where the piles
must be driven to sufficient depth in a competent stratum to
achieve fixity of the pile toes. The earth pressures can be
assessed using conventional methods, but an additional load is
introduced to represent the tie rod load and the whole system is
then analysed to determine the pile length required to give
rotational stability about the pile toe under the applied loads. An
additional length of pile is then added to ensure that toe fixity is
achieved. A check must be made to ensure that horizontal
equilibrium of the forces acting on the anchorage is achieved.
The bending moments induced in this type of anchorage are
generally large and wherever possible this type of anchorage
should be avoided. Raking piles can often be an economic
alternative to this type of anchorage.
6.5.5 Grouted anchors
An alternative to a deadman anchorage is to use grouted soil or rock
anchors. These consist of a tendon, either bar or strand, which is
grouted over the anchor bond length, to transfer the tension load
into the soil. The part of the tendon between the wall and the anchor
bond length is left ungrouted to ensure the load transfer occurs
beyond the potentially unstable soil mass adjacent to the wall. The
installation of these anchors is usually carried out by specialist
contractors from whom further information may be obtained.
6.6 Walings
Walings usually comprise two rolled steel channel sections placed
back to back and spaced to allow the tie rods to pass between the
channels. This spacing must allow for the diameter of the tie rod
and the thickness of any protective material applied to the rod and
take into account any additional space required if the tie rods are
inclined and will need to pass between the walings at an angle.
It is generally convenient to use at least 100mm deep channel
section diaphragms to create the necessary space positioned at
approximately 2.4m centres – although this dimension will
generally be determined by the width of the sheet piles and the
position of tie bolts and splices.
The walings may be fixed either at the back or front of the
retaining wall. The first arrangement is usually adopted for the
sake of appearances and, in the case of a wall in tidal or
fluctuating water level conditions, to prevent damage to the waling
by floating craft or vice versa.
Chapter 6/10
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Fig 6.6 Typical anchoring arrangements
When the waling is placed behind the wall, it is necessary to use
short anchor bolts and plates at every point of contact between
the piles and the waling to connect them together. Placing the
waling in front of the wall eliminates the need for connection bolts
and this arrangement is therefore more economical.
Splices should be located at a distance of 0.2775 of the tie rod
spacing from a tie rod location as this will be close to the position
of minimum bending moment in the waling. The walings should
be ordered 100mm longer than the theoretical dimensions to
allow for any creep which may develop in the wall as the piles are
driven, one end only of each length being drilled for splicing (if the
splice is to be achieved by bolting). The other end should be plain
for cutting and drilling on site, after the actual length required has
been determined by measurement of the driven piles.
Where inclined ties are used, the vertical component of the
anchor load must not be overlooked and provision must be made
to support the waling, usually in the form of brackets or welded
connections.
Chapter 6/11
Piling Handbook, 8th edition (revised 2008)
Retaining walls
In order to prevent the build up of water on top of the waling after
backfilling, holes should be provided at any low spots and
generally at 3m centres in the webs of the walings.
Where sheet pile anchorages are used, similar walings to those at
the retaining wall are required. These are always placed behind the
anchor piles and consequently no anchor bolts are required.
Where walings form part of the permanent structure they can be
supplied with a protective coating applied before dispatch, a
further coat being applied at site after completion of the works.
6.6.1 Design of walings
For design purposes, the waling may be considered to be simply
supported between the tie rods (which will result in a conservative
bending moment) with point loads applied by the anchor bolts.
The magnitude of the tie bolt load is a function of the bolt spacing
and the design support load per metre run of wall. Alternatively,
the waling can be considered as continuous with allowance being
made for end spans. Although the waling is then statically
indeterminate, it is usual to adopt a simplified approach where the
bending moment is assumed to be wL2/10, w being the calculated
load to be supplied by the anchorage system acting as a uniformly
distributed load and L is the span between tie rods.
When checking the anchorage system for the loss of a tie rod, the
load in the anchorage system is assessed on the basis of the
requirements for a serviceability limit state analysis with no
allowance being made for overdig at excavation level. The
resulting bending moments and tie forces are considered to be
ultimate values and are applied over a length of waling of 2L.
In this extreme condition, it can be demonstrated that, with the
exception of the ties at either end of the external spans, the
bending moment in a continuous waling resulting from the loss of
any tie rod will not exceed 0.3wL2 where w is the support load
calculated for this condition expressed as a UDL and, for
simplicity, L is the original span between tie rods. It is intended
that this estimation is used for an initial assessment of the effect
that loss of a tie rod will have on the structural requirements.
This simplification will enable a check to be made with minimum
effort to ascertain whether the normal design conditions are the
more critical design situations. If the anchorage design proves to
be governed by this extreme case, it may be advantageous to
carry out a more rigorous analysis of the waling arrangement with
a view towards optimising the design.
Chapter 6/12
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.6.2 Ultimate bending capacity of parallel flange channel walings
Table 6.6.2 gives information on the theoretical ultimate bending
capacity of walings formed from ‘back to back’ channels in the
most commonly used steel grades.
It must not be overlooked that the calculated ultimate bending
capacity of the waling will need to be reduced to take into
account torsion, high shear loads and axial loading. The values
are included as an aid to initial section sizing.
Table 6.6.2 Back-to-back channel walings
Yield moment capacity
Dimensions
Weight CS Area Section modulus
Elastic
Plastic
Designation h
b
tw
tf
A
Wy
Wpl,y S235JR S275JR S355JR S235JR S275JR S355JR
2
3
3
mm mm mm mm kg/m
cm
cm
cm
kNm
kNm
kNm
kNm
kNm
kNm
UPN 180
180
70
8
11
44
56.0
300
358
UPN 200
200
75
UPN 220
220
80
9
12.5
51
64.4
382
59
74.8
490
UPN 240
240
85
9.5
13
66
84.6
600
UPN 260
260
90
UPN 280
280
95
10
14
76
96.6
10
15
84
106.6
UPN 300
300 100
10
16
92
117.6
UPN 320
320 100
14
UPN 350
350 100
14
UPN 380
UPN 400
8.5 11.5
82.5
106.5
98.5
84.1
127.1
456
89.8
105.1
135.6
125.4
125.4
161.9
584
115.2
134.8
174.0
160.6
160.6
207.3
716
141.0
165.0
213.0
196.9
196.9
254.2
742
884
174.4
204.1
263.4
243.1
243.1
313.8
896
1064
210.6
246.4
318.1
292.6
292.6
377.7
1070
1264
251.5
294.3
379.9
347.6
347.6
448.7
151.6
1358
1652
319.1
373.5
482.1
454.3
454.3
586.5
16
121
154.6
1468
1836
345.0
403.7
521.1
504.9
504.9
651.8
380 102 13.5
16
126
160.8
1658
2028
389.6
456.0
588.6
557.7
557.7
719.9
400 110
18
144
183.0
2040
2480
479.4
561.0
724.2
682.0
682.0
880.4
14
17.5 119
70.5
The table shows the basic Yield Moment capacity of the walings calculated
as Mel = Ys . Wy and Mpl = Ys . Wpl,y.
Appropriate standards should be used to assess whether the moment
capacity needs to be reduced to take into account:
lateral torsional buckling
high shear loading
axial load
Webs should be checked for buckling and bearing.
Chapter 6/13
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.7 Tie rods
Tie rods are readily available in weldable structural steel complying
with EN10025 grade S235J0 and S355JO but the economies to be
gained from specifying high tensile ties mean that steel with a yield
stress of 500N/mm2 is being specified more and more.
Tie rods may be manufactured from plain round bars with the
threads formed in the parent metal such that the minimum tensile
area will occur in the threaded portion of the bar. Alternatively, they
may be manufactured with upset ends which involves forging the
parent bar to create a larger diameter over the length to be
threaded. Using this process, a smaller diameter bar can be used to
create a given size of thread.
Threads may be produced by cold rolling or machining.
The ultimate resistance of a tie rod is calculated on the basis of the
lowest resistance from either the threaded part of the rod or the
shaft at any time during the life of the structure. It is common
practice to limit the stress in the threaded section of a tie rod to the
lesser of either the yield stress of the steel or a proportion of it’s
ultimate tensile strength - in many current design codes this
proportion is in the region of 70%. The cross section area
applicable to the threaded portion is the net area of the bar allowing
for the loss of area over the depth of the threads.
When calculating the shaft resistance, the stress is taken as the yield
stress of the steel and the tensile area as the gross area of the bar.
Hence the ultimate resistance of the tie rod is the lesser of
or
K . fu . A t
fy . A t
fy . A g
where K is a reduction factor whose value is defined in local
standards;
f u is the ultimate tensile strength of the steel;
A t is the tensile stress area at the threads;
f y is the yield strength of the steel ;
A g is the gross area of the parent bar ;
Individual tie rod manufacturers offer different products and
designers should check manufacturers literature or websites to
ensure that they have the most up to date information.
The following table indicates the nominal steel areas for a range of
tie rods providing threads of a given size. As can be seen, a
smaller diameter parent bar can be used to create a tie rod with a
given thread size when the ends are upset.
Chapter 6/14
Care must be exercised when assessing the ultimate resistance of
the tie rods offered by different manufacturers as the quoted
tensile area in the threaded section may not take into account
manufacturing tolerances for the threading process and
consequently may not be the lowest possible tensile area.
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Table 6.7
Nominal
Thread
size
Nominal
Minimum
thread dia*
mm
Minimum
area under
threads
mm2
M36
32.253
M42
M48
Upset bars
Bar dia
Area of
Main bar
Plain bars
Bar dia
Area of
main bar
mm
mm2
mm
mm2
817
30
707
36
1018
37.763
1120
35
962
42
1385
43.307
1473
40
1257
48
1810
M56
50.840
2030
47
1735
56
2463
M64
58.360
2675
54
2290
64
3217
M72
66.364
3459
61
2922
72
4072
M85
79.364
4947
73
4185
85
5675
M90
84.365
5590
77
4657
90
6362
M100
94.367
6994
87
5945
100
7854
M105
99.368
7755
90
6362
105
8659
M110
104.371
8556
95
7088
110
9503
M120
114.371
10274
105
8659
120
11310
M130
124.371
12149
115
10387
130
13273
M135
129.371
13139
120
11310
135
14313
M140
134.371
14181
123
11882
140
15394
M145
139.371
15249
127
12667
145
16513
M150
144.371
16370
130
13273
150
17671
Note: The optimum bar diameter is generally selected after
considering the actual working load, sacrificial corrosion
allowance and the effects of strain.
* Taking manufacturing tolerances into account when defining the
minimum thread diameter can reduce the tensile area (based on
nominal values) by up to 3% dependent upon the rod diameter.
The load in a tie rod can be difficult to determine with any great
degree of accuracy due to factors such as the variability of the
material retained and arching within the soil. The adoption of fairly
large factors of safety in traditional designs, for what is a safety
critical element, has reflected the uncertainty in this area. Under
the limit state design philosophy adopted in this Handbook, this
practice is continued and the ultimate anchor load is calculated
by the application of a 1.85 factor to the reaction force derived by
calculation based on limit equilibrium methods of analysis.
Reaction forces derived from soil structure interaction methods do
not need to have this factor applied as the effect of arching is
already built in to the analysis.
Chapter 6/15
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Elongation of the tie rods under the design load should be
checked. Movement under imposed loads may be reduced in
many cases by pre-loading the tie rods at the time of installation
to develop the passive resistance of the ground.
The effect of sag of the tie rods and forced deflection due to
settlement of fill should also be considered. Bending stresses
induced at a fixed anchorage may significantly increase the tensile
stress in the tie rod locally. Shear stresses may also be induced if
a tie rod is displaced when the fill settles causing compound
stresses which must be allowed for in the detailed design. This
can often be overcome by provision of articulated joints or
settlement ducts.
6.7.1 Tie rod fittings Tie rod assemblies will normally comprise two lengths of tie rod, a
nut and a plate to suit the bearing conditions at each end, and
usually a turnbuckle to permit length adjustment and to take out
any sag. Individual tie rods are available in lengths up to
approximately 20 metres – actual maximum length is different for
different manufacturers - but if the length of the complete rod is
such that more than two elements of bar are required, couplers
with two right hand threads are also included.
Taper or special washers are used when the axis of a tie rod is not
perpendicular to its seating. In some instances it is desirable to
allow for rotation of the axis to a tie rod relative to the bearing
face, and "articulated" anchorages are available for this purpose.
Plates are needed to transmit the load imposed on sheet piling to
the tie rods and from the tie rods to the anchorages which may be
further sheet piles, a concrete wall or individual concrete blocks.
Washer plates are used when the tie rods are anchored within the
pans of sheet piles and bearing plates when the load is
transmitted through walings. When the load is taken to a concrete
wall or block, anchorage plates distribute the load to the concrete.
The waling loads are transmitted to the anchorages by means of
anchor bolts which also require bearing plates and washers of
sufficient size to provide adequate bearing onto the sheet piling,
walings, etc.
Chapter 6/16
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.7.2 Tie bar corrosion protection
Steel sheet piles are used in many aggressive environments and
consequently corrosion protection or factors influencing effective
life must be considered. Several options are available to the
designer.
1
Unprotected steel
In this situation, consideration should be given to the
probable corrosion rates and consequential loss of bar
diameter in a particular environment as outlined in Chapter 3.
2
Protective Coatings
Several options are available, such as painting, galvanising or
wrapping. The most commonly used method is to wrap tie
bars to give an appropriate level of corrosion protection. The
vulnerable anchor head should be protected, and Fig. 6.7.2
shows a suggested detail. Commonly adopted wrapping
systems are indicated in table 6.7.2.
3
Cathodic protection for tie rods underwater
Fig 6.7.2 Protection system for the anchor head
Chapter 6/17
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Table 6.7.2 Levels of protection using petrolatum fabric reinforced
tape and rubber/bitumen tape
Description
Application
Shop/Site application method
Paste, soft petrolatum
reinforced tape, 15mm overlap
Backfill, non tidal area or
debond through concrete
Shop and site application
Machine or hand application
As above, 55% overlap
Backfilled marine environment
Shop and site application
Machine or hand application
As above, 55% and pvc
overwrap
Backfilled marine environment
also ease of handling
Shop and site application
Machine or hand application
As above, 55% overlap,
Denso Therm overwrap
Aggressive environments,
marine environments
Shop application recommended.
Machine or hand application
Denso Pol 60 tape system,
55% overwrap
Aggressive environments, marine
environments, long life maritime
structures.
Shop application only,
Machine application only
6.7.3 Plates and washers
Dimensions of plates and washers can be obtained from suppliers
literature or from their websites.
6.7.4 Special fittings Any bending in a tie rod, especially in the threaded length
increases the stress locally with the possibility of yield or even
failure if the bending is severe. In order to eliminate the risk of
bending, several options are available which allow rotation of the
axis of a tie rod while maintaining its tensile capacity. These
include forged eye tension bars pinned to brackets on the sheet
pile. Other options are nuts and washers with spherical seatings
or pairs of taper washers which can be rotated to give any angle
between zero and a predetermined maximum. The last two
methods will cater for initial angularity but will not move to
accommodate rotation in service.
Chapter 6/18
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.7.5 Site assembly
Tie rods are normally assembled with component bars supported
to the correct level. Any slack is then taken out by tightening
either a turnbuckle or the nut at one end. It is not possible to
apply more than a nominal tension by tightening the end nut.
Fig 6.7.5 Waling connections at anchorages
Tie bars perform best in pure tension, so it is good practice to
ensure that this is achieved. The following is a recommended
sequence of events to ensure that tie rods are installed and
tensioned correctly.
1
Backfill to approximately 150mm below the finished level for
the ties.
2
Place sand bags every 6m on either side of a
coupler/turnbuckle or articulated joint.
3
Fit settlement ducts over the ties. (check the possibility of
installing hinge joints or hinge turnbuckles)
4
Assemble with turnbuckles or couplers. The minimum screw
in length of bar thread is 1 x nominal thread diameter.
5
Tension from the anchorage outside of the wall to take up the
slack.
6
Tension turnbuckles.
7
Place sand fill over the settlement ducts.
8
Backfill to required level.
This procedure applies to a simple situation and additional
activities may be considered for example, applying pretensioning
to pull the piles in before final backfilling, stressing after backfilling
to prevent future movement due to subsequent loading.
Further information on stressing is available on request from tie
rod manufacturers.
Chapter 6/19
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.8 Example calculations
This section contains sample calculations employing limit state
design for the following cases:
1
Cantilever retaining wall.
2
Tied wall with free earth support.
3
Tied wall with fixed earth support.
4
Balanced anchorage.
In all the following examples, the friction angles indicated are
moderately conservative and need to be factored to obtain design
values
6.8.1 Cantilever retaining wall
A wall is to be built to support a retained height of 3.6 m of sandy
soils. The effective wall height = 3.6m + 10% = 3.96m say 4.0m
(unplanned excavation allowance is 10% with 0.5m maximum)
Minimum surcharge loading = 10 kN/m2
Loose fine sand
Ka = 0.317
Kp = 3.963
Compact fine sand
Ka = 0.260
Kp = 5.329
Fig 6.8.1a
γ=14.7 kN/m3
γsat=19.1 kN/m3
φ=32°
γ=15.4 kN/m3
γsat=19.4 kN/m3
φ=37°
γw=9.81 kN/m3
Chapter 6/20
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Active pressures
Pa at 0.00m below G.L. in loose sand
= 0.317 x 10.00 + 0.00
= 3.17 kN/m2
Pa at 5.00m below G.L. in loose sand
= 0.317 x 83.50 + 0.00
= 26.47 kN/m2
Pa at 5.00m below G.L. in compact sand
= 0.260 x 83.50 + 0.00
= 21.71 kN/m2
Pa at 6.00m below G.L. in compact sand
= 0.260 x 98.90 + 0.00
= 25.71 kN/m2
Pa at 10.00m below G.L. in compact sand
= 0.260 x 137.26 + 39.24
= 74.93 kN/m2
Passive pressures
Pp at 4.00m below G.L. in loose sand
= 3.963 x 0.00 + 0.00
= 0.00 kN/m2
Pp at 5.00m below G.L. in loose sand
= 3.963 x 14.70 + 0.00
= 58.26 kN/m2
Pp at 5.00m below G.L. in compact sand
= 5.329 x 14.70 + 0.00
= 78.34 kN/m2
Pp at 6.00m below G.L. in compact sand
= 5.329 x 30.10 + 0.00
= 160.40 kN/m2
Pp at 10.00m below G.L. in compact sand
= 5.329 x 68.46 + 39.24
= 404.06 kN/m2
Fig 6.8.1b
Since the pressure diagram is not uniform the depth of the toe is
best found by trial and error which results in a length of 7.022m.
Chapter 6/21
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Take moments about the toe at 7.022m depth
Active force
Force
kN/m
Moment abt toe
kNm/m
3.17 x 5.000 x 1/2
=
7.93 x 5.355
=
42.44
26.47 x 5.000 x 1/2
=
66.17 x 3.689
=
244.12
21.71 x 1.000 x 1/2
=
10.86 x 1.689
=
18.33
1/2
=
12.86 x 1.355
=
17.42
25.71 x 1.022 x 1/2
=
13.14 x 0.681
=
8.95
1/2
=
19.57 x 0.341
=
25.71 x 1.000 x
38.29 x 1.022 x
6.67
130.53
337.93
Force
kN/m
Moment abt toe
kNm/m
Passive force
58.26 x 1.000 x 1/2
=
29.13 x 2.355
=
68.60
78.34 x 1.000 x 1/2
=
39.17 x 1.689
=
66.16
1/2
=
80.20 x 1.355
=
108.67
160.40x 1.022 x 1/2
=
81.96 x 0.681
=
55.82
1/2
=
113.78 x 0.341
=
160.40x 1.000 x
222.66x 1.022 x
344.24
38.80
338.05
Since the passive moment is marginally greater than the active
moment the length is OK
To correct the error caused by the use of the simplified method
the depth below the point of equal active and passive pressure is
increased by 20% to give the pile penetration.
Let the point of equal pressure be (4.00 + d) below ground level
Then 58.26 x d = 3.17 + 23.30 x (4.000 + d)
1.00
5.00
Therefore d =
21.81
= 0.407m
58.26 – 4.66
Hence the required pile length
= 4.000 + 0.407 + 1.2 x (3.022 – 0.407) = 7.545m say 7.55m
Zero shear occurs at 5.570m below ground level. (where the area
of the active pressure diagram above the level equals the area of
the passive pressure diagram above the level.)
Chapter 6/22
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Take moments about and above the level of zero shear:
kNm/m
1/2
x 3.903
=
30.93
26.47 x 5.000 x 1/2 x 2.237
=
148.03
21.71 x 0.570 x 1/2 x 0.380
=
2.35
3.17 x 5.000 x
1/2
x 0.190
=
1.30
-58.26 x 1.000 x 1/2 x 0.903
=
-26.30
-78.34 x 0.570 x 1/2 x 0.380
=
-8.48
-125.11 x 0.570 x 1/2 x 0.190
=
-6.77
23.99 x 0.570 x
141.06
Maximum bending moment = 141.1 kNm/m
Since the soil loadings determined in this example are based on
factored soil parameters a partial factor of 1.2 is applied to give
the ultimate design load.
Section modulus of pile required
= 1.2 x 141.1 x 10 3 / 270 = 627 cm 3/m
Hence use PU7(1) piles (z = 670 cm 3/m) not less than
7.55m long in S270GP
However the designer will need to check the suitability of the
section for driving and durability.
(1)
Section properties of the section: see Table 13.1.1
Chapter 6/23
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.8.2 Tied wall with free earth support
A wall is to be built to support a retained height of 7.00m
(including the unplanned excavation allowance with a low tide
level at 5.00m below the top of the wall.
Although the weep holes in the wall will allow the retained soil to
drain the ground water will lag behind the tide and hence the
ground water level on the retained side is assumed to be 1.00m
above the low tide level.
It will be necessary to anchor the top of the wall and the ties are
assumed to act at 1.00m below ground level.
Minimum surcharge loading = 10 kN/m2
Loose fine sand
Ka = 0.317
Kp = 3.963
Compact fine sand Ka = 0.260
Kp = 5.329
Fig 6.8.2a
γ=14.7 kN/m3
γsat=19.1 kN/m3
φ'=32°
γ=15.4 kN/m3
γsat=19.4 kN/m3
φ'=37°
γw=9.81 kN/m3
Active pressures
Chapter 6/24
Pa at 0.00m below G.L. in loose sand
= 0.317 x 10.00 + 0.00
= 3.17 kN/m2
Pa at 4.00m below G.L. in loose sand
= 0.317 x 68.80 + 0.00
= 21.81 kN/m2
Pa at 4.00m below G.L. in compact sand
= 0.260 x 68.80 + 0.00
= 17.89 kN/m2
Pa at 10.00m below G.L. in compact sand
= 0.260 x 126.34 + 58.86
= 91.71 kN/m2
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Passive pressures
Pp at 7.00m below G.L. in compact sand
= 5.329 x 0.00 + 19.62
= 19.62 kN/m2
Pp at 10.00m below G.L. in compact sand
= 5.329 x 28.77 + 49.05
= 202.37 kN/m2
Since the pressure diagram is not uniform the length of pile
required to provide stability (i.e. Active moment = Passive
moment) for rotation about the tie is found by trial and error to be
9.447m
Fig 6.8.2b
Taking moments of the active pressures about the top frame:
Active force
kN/m
3.17 x 4.000 x 1/2
=
6.34 x 0.333
Active moment
kNm/m
=
2.11
1/2
=
43.62 x 1.667
=
72.71
17.89 x 5.447 x 1/2
=
48.72 x 4.816
=
234.65
84.91 x 5.447 x 1/2
=
231.25 x 6.631
21.81 x 4.000 x
329.93
= 1533.43
1842.90
Chapter 6/25
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Taking moments of the passive pressures about the top frame:
Passive force
kN/m
Active moment
kNm/m
19.62 x 2.000 x 1/2
=
19.62 x 5.333
=
104.63
1/2
=
24.00 x 6.816
=
163.62
=
206.38 x 7.631
19.62 x 2.447 x
168.68x 2.447 x
1/2
= 1574.89
250.00
1843.14
Passive moment is close enough to Active moment therefore OK
Tie load = 329.93 – 250.00 = 79.93 kN/m
Zero shear occurs at 5.195m below ground level. (where the area
of the active pressure diagram less the area of the passive
pressure diagram above the level equals the tie load.)
Take moments about and above the level of zero shear:
kNm/m
3.17 x 4.000x 1/2 x
3.862
=
24.49
21.81 x 4.000x 1/2 x
2.528
=
110.27
x
0.797
=
8.52
32.59 x 1.195x 1/2 x
0.398
=
7.75
=
-0.01
17.89 x 1.195x
-1.91 x 0.195x
1/2
1/2
-79.93 x 4.195
x
0.065
= -335.31
-184.29
Maximum bending moment with free earth support
= 184.3 kNm/m
Since the soil loadings determined in this example are based on
factored soil parameters a partial factor of 1.2 is applied to give
the ultimate design load.
For piles in steel grade S270GP Ys = 270 N/mm2
Section modulus of pile required = 1.2 x 184.3 x 10 3 / 270
= 819 cm3/m
Hence use PU8 (1) piles (z = 830 cm3/m) not less than 9.50m long
in S270GP
However the designer will need to check the suitability of the
section for driving and durability.
(1)
Chapter 6/26
Section properties of the section: see Table 13.1.1
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.8.3 Tied wall with fixed earth support
The conditions adopted for the free earth support example are
used again to provide a comparison.
Minimum surcharge loading = 10 kN/m2
Loose fine sand
Ka = 0.317
Kp = 3.963
Compact fine sand
Ka = 0.260
Kp = 5.329
Fig 6.8.3a
γ = 14.7 kN/m2
γsat = 19.1 kN/m2
φ′ = 32°
2
γ = 15.4 kN/m
γsat = 19.4 kN/m2
φ′ = 37°
2
γw = 9.81 kN/m
Active pressures
Pa at 0.00m below G.L. in loose sand
= 0.317 x 10.00 + 0.00
=
Pa at 4.00m below G.L. in loose sand
= 0.317 x 68.80 + 0.00
= 21.81 kN/m2
Pa at 4.00m below G.L. in compact sand
= 0.260 x 68.80 + 0.00
= 17.89 kN/m2
Pa at 12.00m below G.L. in compact sand
= 0.260 x 145.52 + 78.48
= 116.32 kN/m2
3.17 kN/m2
Passive pressures
Pp at 7.00m below G.L. in compact sand
= 5.329 x 0.00 + 19.62
= 19.62 kN/m2
Pp at 12.00m below G.L. in compact sand
= 5.329 x 47.95 + 68.67
= 324.20 kN/m2
Chapter 6/27
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Fig 6.8.3b
The simplified method for a fixed earth analysis assumes that the
point of contraflexure in the bending moment diagram occurs at
the level where the active pressure equals the passive pressure
and hence the frame load can be calculated by taking moments
about this level (Y-Y).
Let Y-Y be 7.00m + d below the retained ground level
where Pa = Pp
Then 17.89 + 98.43 x 3 + 98.43 x d = 19.62 + 304.58 x d
8.00
8.00
5.00
hence 54.80 + 12.304d = 19.62 + 60.916d
therefore d = 35.18 = 0.724m
48.612
Take moments about Y-Y
Force
kN/m
3.17 x 4.000 x 1/2
=
1/2
=
17.89 x 3.724 x 1/2
=
=
=
21.81 x 4.000 x
63.71 x 3.724 x
1/2
-19.62 x 2.000 x 1/2
6.34 x 6.391
=
40.52
43.62 x 5.057
=
220.59
33.31 x 2.483
=
82.71
118.63 x 1.241
=
147.22
-19.62 x 1.391
=
-27.29
1/2
=
-7.10 x 0.483
=
-3.43
-63.71 x 0.724 x 1/2
=
-23.06 x 0.241
=
-5.56
-19.62 x 0.724 x
152.12
Chapter 6/28
Moment abt Y-Y
kNm/m
454.76
Piling Handbook, 8th edition (revised 2008)
Retaining walls
454.76
Then frame load = 6.724 = 67.63 kN/m
The length of pile is found by taking moments about an assumed
toe level such that the moments of all the forces are in equilibrium.
Since the pressure diagram is not uniform, and the equation for a
direct solution will have cubic terms, the pile length is found by
trial and error to be 10.953m
Taking moments about the toe of the pile
kNm/m
3.17 x 4.000 x 1/2
x 9.620
=
60.99
21.81 x 4.000 x 1/2
x 8.286
=
361.44
17.89 x 6.953 x 1/2
x 4.635
=
288.27
103.44 x 6.953 x 1/2
x 2.318
=
833.57
-19.62 x 2.000 x 1/2
x 4.620
=
-90.64
1/2
x 2.635
= -102.18
-260.42 x 3.953 x 1/2 x 1.318
= -678.40
-19.62 x 3.953 x
-67.63 x 9.953
= -673.12
-0.07
To correct the error caused by the use of the simplified method
the depth below the point of contraflexure is increased by 20% to
give the pile penetration.
Hence the required pile length
= 7.00 + 0.724 + 1.2 x (10.953 – 7.724) = 11.599m
Zero shear occurs at 4.779m below ground level. (where the area
of the active pressure diagram above the level equals the top
frame load.)
Take moments about and above the level of zero shear:
kNm/m
1/2
x 3.446
=
21.85
21.81 x 4.000 x 1/2
x 2.112
=
92.13
1/2
x 0.519
=
3.62
27.47 x 0.779 x 1/2
x 0.260
=
2.78
3.17 x 4.000 x
17.89 x 0.779 x
-67.63 x 3.779
= -255.57
-135.19
Maximum bending moment = 135.2 kNm/m
Chapter 6/29
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Since the soil loadings determined in this example are based on
factored soil parameters a partial factor of 1.2 is applied to give
the ultimate design load.
For piles in steel grade S270GP Ys = 270 N/mm2
Section modulus of pile required
= 1.2 x 135.2 x 10 3 / 270 = 601 cm 3/m
Hence use PU6(1) piles (z = 600 cm 3/m) not less than 11.60m long
in S270GP
However the designer will need to check the suitability of the
section for driving and durability.
(1)
Chapter 6/30
Section properties of the section: see Table 13.1.1
Piling Handbook, 8th edition (revised 2008)
Retaining walls
6.8.4 Deadman anchorage example
The following example illustrates the method commonly used for
the design of balanced anchorages. The conditions adopted are
those used to design the retaining wall with fixed earth support
conditions assumed at the toe of the main wall.
Fig 6.8.4
γ = 15.4 kN/m3
γsat = 19.4 kN/m3
φ = 37°
Waling load calculated using factored soil parameters and a fixed
earth support = 68 kN/m
Since the design of the front wall used a Limit Equilibrium
approach
Ultimate load for anchorage design = 1.85 x 68 = 125.8 kN/m
As explained in section 6.5.2 it is usual to provide a robust design
for the anchorage and hence this example assumes a continuous
anchor wall with a suitable waling.
Passive pressure in front of anchorage = Kp γ d
Active pressure behind the anchorage = K a w + K a γ d, where w is
the surcharge loading which is applied, as a worst case, behind
the anchorage wall only
2
Hence T = (K p - K a) γ d - K a wd
2
Chapter 6/31
Piling Handbook, 8th edition (revised 2008)
Retaining walls
This force is assumed to act at 2/3 depth but this may need to be
checked, by taking moments about the toe of the pile for the
various components, where there is a large surcharge and/or a
high water table. If the toe of the pile is below the water table the
calculation should be split and passive and active pressures
calculated for each appropriate level in a manner similar to the
main wall.
Since there is a lack of restraint against upward movement of the
anchor wall skin friction is ignored and hence
Ka = 0.368 and Kp = 2.716
For a 2.85m deep anchorage
2
T = (2.716 - 0.368) x 14.7 x 2.85 - 0.368 x 10.00 x 2.85
2
= 129.7 kN/m > 125.8 kN/m ∴ OK
Average pressure on anchorage = 125.8 = 66.2 kN/m 2
1.90
Bending moment in piles = 0.125wL2 = 0.125 x 66.2 x 1.90 2
= 29.9 kNm/m
(L = actual length of piles = 2 x 2.85 = 1.90m)
3
Since the soil loadings determined in this example are based on
factored soil parameters a partial factor of 1.2 is applied to give
the ultimate design bending moment.
Hence minimum section modulus required
= 1.2 x 29.9 x 103 = 133 cm 3/m
270
Therefore use PU6(1) piles in steel grade S270GP by 1.9m long
Assume the tie rods are at 3.60m centres i.e. every sixth pile.
The tie rods are inclined downwards at an angle of
tan-1 0.9
= 4.85°
10.60
(
)
Then ultimate design load in tie rod
= 1.2 x 125.8 x 3.60 = 545.4 kN
cos 4.85°
Select a tie rod size from manufacturers literature to provide
an ultimate resistance in excess of 545.4kN
Ultimate design load on waling = 1.2 x 125.8 = 151.0 kN/m
Bending moment on waling = 0.1 x 151.0 x 3.60 2 = 195.7 kNm
Maximum shear load = 0.5 x 151.0 x 3.60 = 271.8 kN
(1)
Chapter 6/32
Section properties of the section: see Table 13.1.1
Piling Handbook, 8th edition (revised 2008)
Retaining walls
Subject to a check on torsion and shear, a waling formed from
back to back UPN 240 channel sections in grade S275JO steel
will provide the required moment capacity (Mpl = 196.9 kNm)
However it may be necessary to check the exceptional
circumstance of a tie failing, as outlined in Section 6.5.2.
For this condition a second pressure diagram should be
constructed using un-factored soil parameters and without the
unplanned excavation allowance. The depth to the point of equal
active and passive pressures is found, moments taken about and
above this level and the waling load calculated.
For this wall Ka for the loose sand is 0.262 and for the compact
sand 0.209; Kp for the compact sand is 7.549 and the depth of
excavation without the unplanned excavation allowance is 6.50m.
This gives a waling load of 47.33 kN/m.
Hence the ultimate load for waling design
= 1.85 x 47.33 = 87.6 kN/m
Load in the tierods either side of the failed tie
= 1.2 x 87.6 x 1.5 x 3.60 = 569.7 kN
cos 4.85°
The resistance of the chosen tie rod must be checked against this
revised value and the diameter increased if necessary.
Ultimate design load on waling
= 1.2 x 87.6 = 105.1 kN/m
Max bending moment in waling
= 0.3 x 105.1 x 3.60 2 = 408.6 kNm
Since this is greater than the capacity of the previously designed
waling the proposed section must be increased.
Maximum shear load = 0.5 x 105.1 x 2.0 x 3.60 = 378.4 kN
Subject to a check on torsion and shear, a waling formed from
back to back UPN 300 channel sections in grade S355JO steel
will provide the required moment capacity (Mpl = 448.7 kNm).
Chapter 6/33
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
7
Cofferdams
1
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Contents
Page
7.1
Introduction
1
7.2
Requirements of a Cofferdam
1
7.3
Planning a Cofferdam
2
7.4
Causes of failure
3
7.5
Support arrangements
3
7.6
Design of Cofferdams
4
7.7
Single skin Cofferdams
4
7.8
Cofferdam arrangements
7
7.8.1
Cofferdams for river crossings
7
7.8.2
Cofferdams with unbalanced loading
(dock wall and riverside construction)
8
7.9
Single skin Cofferdam design example
9
7.10
Design of support system
21
7.11
Cofferdam support frames
22
7.12
Strength of waling and struts
23
7.13
Circular Cofferdams
26
7.14
Reinforced concrete walings for circular Cofferdams
28
7.15
Earth filled double-wall and cellular Cofferdams
29
7.16
Double skin / wall Cofferdams
29
7.17
Cellular Cofferdams
30
7.18
Effect of water pressure
30
7.19
Flow nets
33
7.20
Factor of safety against piping
35
7.21
Pump sumps
35
7.22
Sealants
36
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.1 Introduction
The purpose of a cofferdam is to exclude soil and/or water from
an area in which it is required to carry out construction work to a
depth below the surface. Total exclusion of water is often
unnecessary, and in some instances may not be possible, but the
effects of water ingress must always be taken into account in any
calculations.
For basement construction the designer should always consider
incorporating the cofferdam into the permanent works.
Considerable savings in both time and money can be achieved by
using the steel sheet piles as the primary permanent structural
wall. The wall can be designed to carry vertical loading, see
Chapter 10, and by the use of a suitable sealant system be made
watertight. Details of suitable sealant systems can be found in
Chapter 2.
Where control of ground movement is a specific concern the use
of top down construction should be considered. This will ensure
that movement of the top of the wall is restricted with the
introduction of support at ground level prior to excavation starting
and will also remove the possibility of secondary movement
occurring when the lateral soil loading is transferred from the
temporary supports, as they are removed, to the permanent
structure.
There are two principal approaches to cofferdam design. Single
skin structures are most commonly used but for very large or
deep excavations and marine works double wall or cellular gravity
structures may be preferred.
7.2 Requirements of a Cofferdam
The design of a cofferdam must satisfy the following criteria:• The structure must be able to withstand all the various loads
applied to it.
• The quantity of water entering the cofferdam must be
controllable by pumping.
• At every stage of construction the formation level must be stable
and not subject to uncontrolled heave, boiling or piping.
• Deflection of the cofferdam walls and bracing must not affect
the permanent structure or any existing structure adjacent to the
cofferdam.
• Overall stability must be shown to exist against out of balance
earth pressures due to sloping ground or potential slip failure
planes.
• The cofferdam must be of an appropriate size to suit the
construction work to be carried out inside it.
Chapter 7/1
Piling Handbook, 8th edition (revised 2008)
Cofferdams
• Temporary cofferdams must be built in such a way that the
maximum amount of construction materials can be recovered
for reuse.
7.3 Planning a Cofferdam
The designer of a cofferdam must have an established set of
objectives before commencing the design. The sequence of
construction activities must be defined in order that the design
can take into account all the load cases associated with the
construction and dismantling of the cofferdam. From this
sequence the designer can identify the critical design cases and
hence calculate the minimum penetrations, bending moments and
shear forces to determine the pile section and length required.
As part of the analysis of the construction activities the designer
should undertake a risk assessment of the effect of any deviation
from the planned sequence. Such deviations may be in the form
of over excavation at any stage, inability to achieve the required
pile penetration, installation of the support at the wrong level or
the imposition of a large surcharge loading from construction
plant or materials. If any stage in the cofferdam construction is
particularly vulnerable then contingency plans should be
developed to minimise any risk and the site management should
be informed to limit the possibility of critical conditions being
realised.
The majority of cofferdams are constructed as temporary works
and it may be uneconomic to design for all possible loading
cases. Decisions will have to be taken, normally involving the site
management, to determine the level of risk that is acceptable
when assessing the design cases; such a situation may occur
when assessing hydraulic loading on a cofferdam. Flood
conditions tend to be seasonal and provision of a cofferdam
which will exclude water at all times may involve a substantial
increase in pile size and strength as well as increased framing. In
an extreme flood condition the design philosophy may involve
evacuation of the cofferdam and allowing it to overtop and flood.
Under these conditions the designer must allow for the
overtopping, considering the effect of the sudden ingress of water
on the base of the cofferdam and the effect that any trapped
water may have on the stability when the flood subsides.
Prior to the commencement of construction the site area should
be cleared to permit plant and guide frames to be set up.
Excavation should not begin until all the plant and materials for
supporting the piles are readily available including pumping
equipment where necessary.
Once excavation is complete the cofferdam and support frames
should be monitored to ensure that they are performing as
Chapter 7/2
Piling Handbook, 8th edition (revised 2008)
Cofferdams
expected and to provide as early a warning as possible of any
safety critical problems. It is good practice to maintain a written
record of such monitoring - in the UK this is a legal requirement.
Some possible causes of failure are given below and it will be
seen that a number of them relate to problems that may well
occur after the cofferdam is finished.
7.4 Causes of failure There are many possible causes of cofferdam failure but in
practice it can generally be attributed to one or more of the
following:
• Lack of attention to detail in the design and installation of the
structure.
• Failure to take the possible range of water levels and conditions
into account.
• Failure to check design calculations with information discovered
during excavation.
• Over excavation at any stage in the construction process.
• Inadequate framing (both quantity and strength) provided to
support the loads.
• Loading on frame members not taken into account in the design
such as walings and struts being used to support walkways,
materials, pumps etc..
• Accidental damage to structural elements not being repaired.
• Insufficient penetration to prevent piping or heave. Failure to
allow for the effect on soil pressures of piping or heave.
• Lack of communication between temporary works and
permanent works designers; designers and site management or
site management and operatives.
In many cases failure may result from the simultaneous
occurrence of a number of the above factors, any one of which
might not have been sufficient, on its own, to cause the failure.
7.5 Support arrangements
The arrangement of supports to a cofferdam structure is the most
critical part of a cofferdam design. The level at which the support
is provided governs the bending moments in the sheet piles and
the plan layout governs the ease of working within the structure.
Whilst structural integrity is paramount, the support layout must
be related to the proposed permanent works construction
activities causing the minimum obstruction to plant and materials
access. As a general rule simplicity should always be favoured.
Chapter 7/3
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Support frames should be located such that concrete lifts can be
completed and the support load transferred to the permanent
works before the frame is removed. Clearance to starter bars for
the next lift should be considered when positioning frames.
The clear space between frame members should be optimised to
provide the largest possible uninterrupted area without the need
for excessively large structural elements. Positioning of support
members is often a matter of experience.
7.6 Design of Cofferdams
The design of embedded retaining walls is covered in general
terms in chapter 5 but the following comments are of particular
relevance to the design and construction of cofferdams.
The life of the cofferdam structure must be assessed in order that
the appropriate geotechnical parameters for the soils, in which the
cofferdam is to be constructed, can be selected. In the majority
of cases total stress parameters can be used since the cofferdam
is a temporary structure. However the susceptibility of any clay to
the rapid attainment of a drained state must be assessed by the
designer and if there is any doubt a check should be made on the
final structure using effective stress parameters.
As a rule of thumb it is recommended that cofferdams which are
to be in service for three months or more should be designed
using effective stress strength parameters. However, the
presence of silt laminations or layers within clays can lead to very
rapid attainment of drained conditions and hence it may be
appropriate to use effective stress parameters for much shorter
periods.
7.7 Single skin Cofferdams
Single skin cofferdams are typically formed of sheet piles supported
either by means of internal props or external anchors. The
mechanics of single skin cofferdam design are those already
outlined in Chapters 5 and 6. The piles are considered to be simply
supported between frames and below the lowest frame and will
need to be driven to such a level, depending on the type of soil, as
to generate sufficient passive resistance. However, where there are
at least two frames, if the cut-off of the piles below the excavation is
insufficient to provide the necessary passive support the wall will still
be stable and the pile below the lowest frame can be considered as
a cantilever. This will, however, give rise to large loads in the lowest
frame and should be avoided whenever possible.
In all cases the penetration below formation level will need to be
sufficient to control the infiltration of water into the excavation.
Chapter 7/4
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Records should be kept during driving for any indication of
declutching of the piles. In such a case it may be necessary to
grout behind the piles in order to control seepage. Cantilever pile
cofferdams can be formed but have the same limitations as
cantilever retaining walls particularly in terms of the achievable
retained height.
When the cofferdam has very large plan dimensions, but relatively
shallow depth, it is often more economical to incorporate inclined
struts or external anchorages similar to those described in
chapter 6. It should not however be forgotten that the installation
of external anchorages requires space which is outside the
cofferdam area and wayleaves may be required to install the
anchors under adjacent properties.
For a typical cofferdam with a depth exceeding 3m, a system of
internal frames in the form of steel sections or proprietary bracing
equipment is normally employed.
The design should be undertaken in stages to reflect accurately
the construction process. Typically the sequence of operations
would be to excavate and dewater to just below top frame level
then install the first frame; this procedure being repeated for each
successive frame. In the case of cofferdams in water it should be
noted that the stresses occurring during dewatering and frame
installation may be considerably in excess of those in the
completed cofferdam. For cofferdams in water it is advisable to
use a proprietary interlock sealant as described in Chapter 2.
When a cofferdam is to be used solely for the purpose of
excluding water and the depth of soil to be excavated is only
nominal it is often more efficient to install all the framing under
water before commencing dewatering.
Fig 7.7.1 shows the optimum spacing of frames for this method of
construction. The spacing results in approximately equal loading
on the second and successive frames. Figure 7.7.2 indicates the
maximum spacing between the top and second frames with
respect to section modulus of the pile wall.
Chapter 7/5
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Fig 7.7.1
External top waling & tie rod
h
Water Level
2.45h
1.87h
2.18h
Walings
1.5h
Struts
Sea or river bed
D = depth of cut-off
The above is based on the approximate equation:h3 = 1.3 x Z x fy x 10 - 3
where Z = section modulus in cm 3/m
It should be noted that when depth (h) exceeds about 8m the
waling loads may become excessive.
Fig 7.7.2 Depth v Section Modulus
Section Modulus cm3/m
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5.0
Depth h (metres)
6.0
7.0
8.0
9.0
10.0
11.0
12.0
S270GP
Chapter 7/6
S355GP
S390GP
S430GP
5000
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.8 Cofferdam arrangements
7.8.1 Cofferdams for river crossings
When a pipeline has to be laid under a river bed and it is not
possible to close off the waterway the cofferdam may be
constructed in two or more stages using the arrangement shown
in fig 7.8.1.
Fig 7.8.1
C9 Junctions
Chapter 7/7
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.8.2 Cofferdams with unbalanced loading
(dock wall and riverside construction)
This type of cofferdam is usually subjected to greater loading on
the landward side due to soil pressure plus construction loads
hence special precautions may be needed to overcome the
resulting unbalanced loading. The method used will, of course,
depend upon the specific site conditions but the following
methods are suggested as general practice subject to approval by
the relevant supervising authority:• Method A – the removal of soil from the landward side
• Method B – the use of ‘fill’ on the water side of the cofferdam
• Method C – the use of external anchorages to the landward side
• Method D – the use of raking struts inside the cofferdam
These methods are illustrated in Fig 7.8.2.
Fig 7.8.2 Construction of cofferdams in river banks
River bank
excavated to
natural slope
Fill deposited
outside cofferdam
METHOD B
METHOD A
Tie rods and
anchorages
METHOD C
Chapter 7/8
Raking
struts
METHOD D
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.9 Single skin Cofferdam design example
The following example is based upon the soil conditions used for
the earth pressure calculation example, at a nominal excavation
depth of 7.90m, included in Chapter 4. A number of issues in the
design of cofferdams are illustrated in this example. The iterative
nature of cofferdam design, particularly for the positioning of
frames, lends itself to computer calculation methods but this
example has been manually prepared to illustrate the steps to be
followed in the calculation process.
The diagram below indicates the soil stratification and relevant
properties, the water levels on each side of the wall and the
proposed final excavation level. The active earth pressures are
those calculated previously, in the example in Chapter 4 for the
short term total stress condition. This is considered to be
appropriate for a temporary works construction that will only be
open for a limited period of time. The passive pressures are
calculated for the short term total stress condition, for the
appropriate excavation level at each stage.
Fig 7.9.1
SURCHARGE 10 kN/m3
3.17
1.2m
GWL. -1.20m
8.76
1.2m
24.07
9.73
-2.40m
Loose Fine Sand
γ=14.7 kN/m2 φ=32°
γsat=19.1 kN/m2
γw=9.81 kN/m2
Soft Clay
γ=17.2 kN/m2
Su=25 kN/m2
3.70m
7.90m
-6.10m
73.37
63.21
Sand and Gravel
γsat=20.6 kN/m2
φ=40°
4.90m
123.39
108.97
0.20m
Unplanned
-11.00m
231.62
165.91
Firm Clay
γ=18.6 kN/m2
Su=65 kN/m2
258.91
201.97
TOTAL STRESS (SHORT TERM)
TYPICAL SECTION
PRESSURE DIAGRAM kN/m2
The proposed construction sequence has been assumed to be:
1 Install sheet piles and excavate, including dewatering, for
top frame
2 Install top frame and excavate, including dewatering, for
bottom frame
3 Install bottom frame and excavate to the final level
In this example, the analysis of the sheet piles assumes the
presence of a hinge at the lower prop position to make the
problem statically determinate. The problem can, using this
Chapter 7/9
Piling Handbook, 8th edition (revised 2008)
Cofferdams
assumption, be treated as two single propped retaining walls. It is
also assumed that the control of excavation levels will be good and
therefore no allowance is made, in the intermediate construction
stages, for unplanned excavation. For the final construction stage
an allowance of 0.20m of over excavation will be included.
Stage 1 : Excavate for Top Frame
Before placing the top frame the piles will act in cantilever. The
pressure diagram for this case, assuming excavation to 1.5m, is
given in the figure below. Clearly, in this example, the pile length
and bending strength required for later stages will be much
greater than required at this initial stage and hence no
calculations have been carried out.
Fig 7.9.2
3.17
8.76
24.07
9.73
41.97
58.01
121.65
73.37
63.21
PRESSURE DIAGRAM Stage 1 kN/m2
Stage 2 : Excavate for Bottom Frame
The top frame is assumed to be 1m below the ground surface. We
will assume in this example that the lower frame is positioned
5.5m below the ground surface. This assumption is based on
experience to provide clearance for construction of the base slab
and wall kicker.
The excavation depth required to install the lower frame, providing
sufficient working space, is therefore 6.1m.
Pp at 6.1m below ground level in sand and gravel
= 6.493 x 0.00
= 0 kN/m2
Pp at 11m below ground level in sand and gravel
= (6.493 x 52.87) + 48.07
= 391.35 kN/m2
Pp at 11m below ground level in firm clay
= 1.00 x 100.94 + (2.45 x 65/1.5)
= 207.11 kN/m2
Pp at 16m below ground level in firm clay
= 1.00 x 193.94 + (2.45 x 65/1.5)
= 300.11 kN/m2
Chapter 7/10
Piling Handbook, 8th edition (revised 2008)
Cofferdams
The pressure diagram for this condition is given below:
Fig 7.9.3
3.17
1.20m
1.00m
8.76
1.20m
24.07
9.73
4.523m
46.25
3.70m
6.10m
Zero Shear
0.935m
73.37
63.21
Y
Y 74.68
4.252m
123.39
108.97
391.35
207.11
300.11
201.97
PRESSURE DIAGRAM
Fixed Earth Stage 2 kN/m2
Fixed Earth Support Option
At this stage it may be appropriate to consider a fixed earth support
condition as the pile length needed in the final stage may well be
long enough to provide fixity at the toe for this lesser excavation
depth. Since the simplified method assumes that the point of
contraflexure in the bending moment diagram occurs at the level
where the active pressure equals the passive pressure the frame
load can be calculated by taking moments about this level (Y-Y).
Let Y-Y be y below –6.10m level where Pa = Pp
Then 63.21 + 60.18 x y = 391.35 x y
4.9
4.9
hence y = 63.21 x 4.9/331.17 = 0.935m
Take moments about Y-Y
3.17
8.76
8.76
24.07
9.73
73.37
63.21
74.68
-74.68
x
x
x
x
x
x
x
x
x
1.200
1.200
1.200
1.200
3.700
3.700
0.935
0.935
0.935
x
x
x
x
x
x
x
x
x
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
1/2
=
=
=
=
=
=
=
=
=
Force
kN/m
1.90
5.26
5.26
14.44
18.00
135.73
29.55
34.91
-34.91
210.14
x
x
x
x
x
x
x
x
x
6.635
6.235
5.435
5.035
3.402
2.168
0.623
0.312
0.312
Moment abt Y-Y
kNm/m
=
12.62
=
32.77
=
28.57
=
72.72
=
61.24
=
294.27
=
18.41
=
10.89
=
-10.89
520.60
Chapter 7/11
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Then frame load = 520.60 = 86.26 kN/m
6.035
The length of pile is found by taking moments about an assumed
toe level such that the moments of all the forces are in equilibrium
From the calculation above
total active force above –6.10m
= 180.59 kN/m
total active moment above –6.10m = 502.19 kNm/m
This force acts at 502.19 = 2.781m above Y-Y
180.59
or 1.846m above –6.10m
Assume the pile penetration below –6.10m is d
Then taking moments about the toe
clockwise moments =
2
60.18xd) xd2
180.59 x (1.846+d) + 63.21 x 2d + (63.21+
2
3
4.9
6
3
anticlockwise moment = 391.35 x d + 86.26 x (5.10+d)
4.9
6
Equating clockwise moments to anticlockwise moments produces
a cubic equation which is solved by successive approximations
giving d= 4.252m.
To correct the error caused by the use of the simplified method
the depth below the point of contraflexure is increased by 20% to
give the pile penetration.
Hence the required pile length
= 6.10 + 0.935 + 1.2 x (4.252 – 0.935) = 11.015m say 11.02m
Zero shear occurs at 4.523m below ground level. (Where the area
of the active pressure diagram above the level equals the top
frame load).
Take moments about and above the level of zero shear:
kNm/m
3.17 x 1.200 x 1/2 x 4.123
=
7.84
8.76 x 1.200 x 1/2 x 3.723
=
19.57
8.76 x 1.200 x 1/2 x 2.923
=
15.36
24.07 x 1.200 x 1/2 x 2.523
=
36.44
9.73 x 2.123 x 1/2 x 1.415
=
14.61
46.25 x 2.123 x 1/2 x 0.708
=
34.76
-86.26 x 3.523
=
-303.89
-175.31
Maximum bending moment with fixed earth support = 175.3 kNm/m
Chapter 7/12
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Free Earth Support Option
However if the pile length for the final stage is shorter than
11.02m, the design for this intermediate stage should be
considered as free earth. The passive pressures are as before
and the pressure diagram is shown below:
Fig 7.9.4
3.17
1.00m
1.20m
8.76
1.20m
24.07
9.73
4.926m
6.10m
3.70m
53.18
Zero Shear
73.37
63.21
2.688m
96.22
123.39
214.68
108.97
391.35
207.11
300.11
201.97
PRESSURE DIAGRAM
Free Earth Stage 2 kN/m2
The length of pile required to provide stability (i.e. Active moment
= Passive moment) for rotation about the top frame is found by
trial and error to be 8.788m
Taking moments of the active pressures about the top frame:
Active Force
kN/m
Active Moment
kNm/m
3.17 x 1.200 x 1/2
=
1.90
x
-0.600
=
-1.14
8.76 x 1.200 x 1/2
=
5.26
x
-0.200
=
-1.05
8.76 x 1.200 x 1/2
=
5.26
x +0.600
=
3.15
24.07 x 1.200 x 1/2
=
14.44
x +1.000
=
14.44
9.73 x 3.700 x 1/2
=
18.00
x +2.633
=
47.40
73.37 x 3.700 x 1/2
=
135.73
x +3.867
=
524.89
63.21 x 2.688 x 1/2
=
84.95
x +5.996
=
509.39
96.22 x 2.688 x 1/2
=
129.32
x +6.892
=
891.27
394.86
1988.35
Chapter 7/13
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Taking moments of the passive pressure about the top frame:
Passive force = 214.68 x 2.688 x 1/2 = 288.53 kN/m
Passive moment = 288.53 x 6.892 = 1988.55 kNm/m
[equal to Active Moment therefore OK]
Top frame load = 394.86 – 288.53 = 106.33 kN/m
Zero shear occurs at 4.926m below ground level. (Where the area
of the active pressure diagram above the level equals the top
frame load).
Take moments about and above the level of zero shear:
3.17 x 1.200 x 1/2 x 4.526
8.76 x 1.200 x 1/2 x 4.126
8.76 x 1.200 x 1/2 x 3.326
24.07 x 1.200 x 1/2 x 2.926
9.73 x 2.526 x 1/2 x 1.684
53.18 x 2.526 x 1/2 x 0.842
-106.33 x 3.926
=
=
=
=
=
=
=
kNm/m
8.61
21.69
17.48
42.26
20.69
56.55
-417.45
-250.17
Maximum bending moment with free earth
support = 250.2 kNm/m
Final Stage : Excavate to Formation Level
With the lower frame installed at 5.5m below ground level
excavation is carried out to final level. The design is to include for
0.20m of unplanned excavation so the passive pressures are
calculated for an excavation depth of 8.10m
Pp at 8.1m below ground level in sand and gravel
= 6.493 x 0.00
= 0 kN/m2
Pp at 11m below ground level in sand and gravel
= (6.493 x 31.29) + 28.45
= 231.62 kN/m2
Pp at 11m below ground level in firm clay
= 1.00 x 59.74 + (2.45 x 65/1.5)
= 165.91 kN/m2
Pp at 16m below ground level in firm clay
= 1.00 x 152.74 + (2.45 x 65/1.5)
= 258.91 kN/m2
Chapter 7/14
Piling Handbook, 8th edition (revised 2008)
Cofferdams
The pressure diagram for this condition is given below:
Fig 7.9.5
3.17
1.00m
1.20m
8.76
1.20m
3.661m
24.07
9.73
5.50m
Zero Shear
31.42
7.743m
8.10m
3.70m
63.05
73.37
63.21
11.016m
Zero Shear
83.39
4.90m
123.39
231.62
165.91
108.97
109.27
166.21
258.91
201.97
PRESSURE DIAGRAM Final stage kN/m2
The depth of cut off is found by considering the piles to be simply
supported at the bottom frame position due to the assumption of
a hinge at the support position.
Consider first the lower span. The pile length for stability is found,
by trial and error, to be 11.016m.
Taking moments of the active pressures about the bottom frame:
Active Force
kN/m
63.05 x
73.37 x
63.21 x
123.39x
108.97x
109.27x
0.600
0.600
4.900
4.900
0.016
0.016
x
x
x
x
x
x
1/2
1/2
1/2
1/2
1/2
1/2
=
=
=
=
=
=
18.92
22.01
154.86
302.31
0.87
0.87
499.84
Active Moment
kNm/m
x
x
x
x
x
x
0.200
0.400
2.233
3.867
5.505
5.511
=
=
=
=
=
=
3.78
8.80
345.81
1169.02
4.80
4.82
1537.03
Chapter 7/15
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Taking moments of the passive pressure about the bottom frame:
Passive Force
kN/m
231.62x 2.900 x 1/2
165.91x 0.016 x 1/2
166.17x 0.016 x 1/2
=
=
=
Active Moment
kNm/m
335.85
1.33
1.33
338.51
x
x
x
4.533
5.505
5.511
=
=
=
1522.40
7.31
7.33
1537.04
(Active Moment and Passive Moment are equal therefore OK)
For the lower span bottom frame load
= 499.84 – 338.51 = 161.33 kN/m
Zero shear occurs at 7.743m below ground level. (This is where
the area of the active pressure diagram below the bottom frame
and above the zero shear level equals the bottom frame load
calculated above).
Take moments about and above the level of zero shear
(for the lower span):
kNm/m
83.39
63.21
73.37
63.05
x
x
x
x
1.643 x 1/2 x
1.643 x 1/2 x
0.600 x 1/2 x
0.600 x 1/2 x
-161.33 x
0.548
1.095
1.843
2.043
2.243
=
=
=
=
=
37.54
56.86
40.57
38.64
-361.86
-188.25
Now consider the upper span
Taking moments of the active pressures about the bottom frame:
Active Force
kN/m
3.17
8.76
8.76
24.07
9.73
63.05
x
x
x
x
x
x
1.200
1.200
1.200
1.200
3.100
3.100
x
x
x
x
x
x
1/2
1/2
1/2
1/2
1/2
1/2
=
=
=
=
=
=
1.90
5.26
5.26
14.44
15.08
97.73
139.67
Active Moment
kNm/m
x
x
x
x
x
x
5.100
4.700
3.900
3.500
2.067
1.033
Then top frame load = 237.57/4.500 = 52.79 kN/m
And hence total load in bottom frame
= (139.67 – 52.79) + 161.33 = 248.21 kN/m
Zero shear occurs at 3.661m below ground level.
Chapter 7/16
=
=
=
=
=
=
9.70
24.70
20.50
50.55
31.17
100.95
237.57
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Take moments about and below the level of zero shear:
kNm/m
31.42 x 1.839 x 1/2 x 0.613
63.05 x 1.839 x 1/2 x 1.226
-86.88 x 1.839
=
=
=
17.71
71.08
-159.77
-70.98
Table 7.9.1 Summary
Stage 2
Final Stage
Fixed Earth Free Earth
Required Pile Length
Max. bending Moment
Top Frame Load
Bottom Frame Load
m
KNm/m
KN/m
KN/m
11.02
175.3
86.26
-
8.79
250.2
106.33
-
11.02
188.3
52.79
248.21
Fixed earth support at stage 2 can be assumed since the pile
length required is not greater than the length required for the final
stage.
Since the soil loadings determined in this example are based on
factored soil parameters a partial factor of 1.2 is appropriate to
give the ultimate design load.
Section modulus of pile required for S270GP steel.
= 1.2 x 188.3 x 103 / 270
= 837 cm3/m
Section modulus of pile required for S355GP steel.
= 636 cm3/m
= 1.2 x 188.3 x 103 / 355
To provide control over the inflow of ground water it would be
sensible to ensure the piles are toed into the underlying clay by
not less then 0.3m which requires a pile of 11.3m long.
Hence use PU 9(1) piles (z = 915 cm3/m) in steel grade S270GP or
PU 7(1) (z = 670cm3/m) in steel grade S355GP not less than
11.3m long.
However the designer will need to check the suitability of the
section for driving. See chapter 11.
In accordance with the recommendation in Section 5.14 the
calculated propping loads should be increased by 85 per cent.
Also to provide the ultimate design load for structural design a
partial factor of 1.2 should be applied.
Hence the ultimate design loads are:Top Frame
= 1.85 x 1.2 x 86.26
= 191.5 kN/m
Bottom Frame
= 1.85 x 1.2 x 248.21
= 551.0 kN/m
(1)
Section properties of the section: see Table 13.1.1
Chapter 7/17
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Check on Effective Stress Loading for the Final Stage
Since the clay strata are inter-bedded with free draining material
then it is possible that they may reach a drained state during the
period while the cofferdam is open and it may be appropriate to
check the final stage in the effective stress condition.
Effective stress active pressures are as the example in chapter 5,
so calculate the appropriate passive pressures.
Excavate to final level. The design has included for 0.20m of
unplanned excavation so the passive pressures are calculated for
an excavation depth of 8.10m.
Pp at 8.1m below ground level in sand and gravel
= 6.493 x 0.00
= 0 kN/m2
Pp at 11m below ground level in sand and gravel
= (6.493 x 31.29) +28.45
= 231.62 kN/m2
Pp at 11m below ground level in firm clay
= 2.512 x 31.29 +(3.170 x 2/1.2) +28.45 = 112.33 kN/m2
Pp at 16m below ground level in firm clay
= 2.512 x 75.24 +(3.170 x 2/1.2) +77.50 = 271.79 kN/m2
The pressure diagram for this condition is given below:
Fig 7.9.6
3.17
1.00m
1.20m
8.76
1.20m
3.550m
24.07
30.93
5.50m
Zero Shear
46.41
7.848m
3.70m
8.10m
72.66
80.74
63.21
14.529m
Zero Shear
85.08
4.90m
146.75
112.33
123.39
195.15
231.62
224.88
271.79
215.32
EFFECTIVE STRESS PRESSURE DIAGRAM
Final stage kN/m
2
It can clearly be seen that in the clay strata the active pressures
have increased while the passive have decreased compared with the
total stress condition previously considered hence it is necessary to
calculate the stability and structural loads for this condition.
Chapter 7/18
Piling Handbook, 8th edition (revised 2008)
Cofferdams
As before the depth of cut off is found by considering the piles to
be simply supported at the bottom frame position due to the
assumption of a hinge at the support position.
Consider first the lower span. The pile length for stability is
found, by trial and error, to be 14.529m.
Taking moments of the active pressures about the bottom frame:
Active Force
kN/m
72.66
80.74
63.21
123.39
146.75
195.15
x
x
x
x
x
x
0.600
0.600
4.900
4.900
3.529
3.529
x
x
x
x
x
x
1/2
1/2
1/2
1/2
1/2
1/2
=
=
=
=
=
=
21.80
24.22
154.86
302.31
258.94
344.34
1106.47
Active Moment
kNm/m
x
x
x
x
x
x
0.200
0.400
2.233
3.867
6.676
7.853
=
=
=
=
=
=
4.36
9.69
345.81
1169.02
1728.69
2704.12
5961.69
Taking moments of the passive pressure about the bottom frame:
Passive Force
kN/m
231.62x 2.900 x 1/2
112.33 x 3.529 x 1/2
224.88 x 3.529 x 1/2
=
=
=
335.85
198.21
396.80
930.86
Active Moment
kNm/m
x 4.533
x 6.676
x 7.853
=
=
=
1522.40
1323.23
3116.08
5961.71
[Active Moment and Passive Moment are equal therefore OK]
For the lower span bottom frame load =
1106.47 – 930.86 = 175.61 kN/m
Zero shear occurs at 7.848m below ground level for the lower
span.
Take moments about and above the level of zero shear for the
lower span:
kNm/m
85.08
63.21
80.74
72.66
x
x
x
x
1.748 x 1/2 x 0.583
1.748 x 1/2 x 1.165
0.600 x 1/2 x 1.948
0.600 x 1/2 x 2.148
-175.61 x 2.348
=
=
=
=
=
43.35
64.36
47.18
46.82
-412.33
-210.62
Chapter 7/19
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Now consider the upper span
Taking moments of the active pressures about the bottom frame:
Active Force
KN/m
3.17
8.76
8.76
24.07
30.93
72.66
x
x
x
x
x
x
1.200
1.200
1.200
1.200
3.100
3.100
x
x
x
x
x
x
1/2
1/2
1/2
1/2
1/2
1/2
=
=
=
=
=
=
1.90
5.26
5.26
14.44
47.94
112.62
187.42
Active Moment
kNm/m
x
x
x
x
x
x
5.100
4.700
3.900
3.500
2.067
1.033
=
=
=
=
=
=
9.70
24.70
20.50
50.55
99.10
116.34
320.89
Then top frame load = 320.89/4.500 = 71.31 kN/m
And hence total load in bottom frame
= (187.42 – 71.31) + 175.61 = 291.72 kN/m
Zero shear occurs at 3.550m below ground level.
Take moments about and below the level of zero shear:
kNm/m
46.41 x 1.950 x 1/2 x 0.650
72.66 x 1.950 x 1/2 x 1.300
-116.11 x 1.950
=
=
=
29.41
92.10
-226.41
-104.90
Table 7.9.2 Summary
Short term design
All stages
Required pile length
Max. bending moment
Max. load in top frame
Max. load bottom frame
m
KNm/m
KN/m
KN/m
Long term design
Final stages
11.02
188.3
86.26
248.21
14.53
210.6
71.31
291.72
Hence for a long term effective stress design
Section modulus of pile required for S270GP steel
= 936 cm3/m
= 1.2 x 210.6 x 103 / 270
Section modulus of pile required for S355GP steel
= 712 cm3/m
= 1.2 x 210.6 x 103 / 355
Therefore the original pile specified, PU 9(1) in steel grade S270GP
or PU 7(1) in steel grade S355GP 11.3m long, will have to be
increased to
Either PU 11(1) (Z = 1095 cm3/m) by 14.6m in steel grade S270GP.
Or PU 8(1) (Z = 830 cm3/m) by 14.6m in steel grade S355GP.
In addition the bottom frame should be checked as the frame
loading is increased by some 18%.
(1)
Chapter 7/20
Section properties of the section: see Table 13.1.1
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.10 Design of support system
Traditionally cofferdam bracing was constructed in either timber or
steel, the choice being governed by the loads to be carried.
However over the past ten to fifteen years the increasing use of
proprietary equipment combined with the loss of skilled timbermen
means that it is now exceedingly rare for timber to be used and
virtually all framing is now in steel. The loads on the walings are
obtained from consideration of the same conditions used to obtain
the bending moments in the piles.
For the majority of small to medium sized cofferdams, which will only
be open for a relatively short period, it is probably more economic to
use a proprietary frame or frames on hire and possibly designed by
the supplier. These frames use hydraulic rams to apply a pre-load
and have been developed from the support systems used for
trenches for more than thirty years. At the time of writing props can
be obtained with capacities of up to 2500kN and walings to provide
spans of 20 m. However if large span walings are proposed the
deflections should be checked since these may well be large and will
permit significant movement of the wall and the ground behind.
As an alternative, and for larger cofferdams beyond the scope of the
proprietary equipment, purpose made frames utilising universal
beams and column sections and tubes will be necessary. These
members may require suitable stiffeners to prevent local buckling.
Information on the strength of typical members is given in the tables
below.
Traditionally steel frames have been designed using permissible
stress methods. The use of either serviceability or ultimate limit state
codes of practice is acceptable for determining the appropriate
design value from calculations for the pile wall. However there is a
move towards limit state methods and the load tables included in
this chapter show ultimate loads, based on the UK code BS5950.
The way the framing is detailed can make a significant difference to
the ease with which it is erected and dismantled. Waling beams
should be supported at regular intervals either with brackets welded
to the piles or with hangers, possibly chains, from the top of the
piles. Struts should be fitted with a hanger to support their weight
on the waling while being aligned and fixed in position. Prop design
must include for accidental impact by materials or machinery – the
tables below include an allowance of 10kN applied at mid-span –
and the designer should ensure, by discussion with the contractor’s
site management, that the allowance is adequate for the size of
machines being used. Various sources give guidance on this in the
range 10 – 50 kN. Where the walings do not bear directly on the
piles suitable packers will be required which may be of timber, either
softwood or hardwood, concrete filled bags or steel plates
depending on the loads to be transferred.
Chapter 7/21
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.11 Cofferdam support frames
Fig 7.11
Chapter 7/22
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.12 Strength of walings and struts
Table 7.12.1 Ultimate Capacity Table for Universal Beam Walings
Section Size
254
305
356
406
457
457
533
610
610
x
x
x
x
x
x
x
x
x
146
165
171
178
152
191
210
229
305
x
x
x
x
x
x
x
x
x
Section
Moment Capacity
Classification
Mcx
kNm
31 kg/m
40 kg/m
45 kg/m
60 kg/m
67 kg/m
74 kg/m
92 kg/m
113 kg/m
149 kg/m
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
Plastic
108
171
213
330
400
455
649
869
1220
Shear Capacity
Pv
kN
249
300
406
530
680
679
888
1070
1150
Notes:
The table shows Ultimate Limit State (maximum applied) moment and shear
capacities based on BS5950-1:2000.
Waling capacities are based on S275 material to EN10025.
The moment capacity assumes the shear load to be low ( <60% of shear
capacity). Where the shear load is high the moment capacity will need to be
reduced (see BS5950 cl 4.2.5.3)
The waling will need to be checked for lateral torsional buckling which may
give a reduced bending capacity (see BS5950 cl 4.3.6.2)
Webs should also be checked for bearing and buckling.
When the waling is also subject to axial load the bending capacity will be
reduced and the section should be checked in accordance with
BS5950 cl 4.8.3.3
Chapter 7/23
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Table 7.12.2 Ultimate Capacity Table for Horizontal Universal Column Struts
Universal Column
Designation
D x B x wt(kg/m)
152
203
203
254
254
305
305
356
356
x
x
x
x
x
x
x
x
x
152
203
203
254
254
305
305
368
368
x
x
x
x
x
x
x
x
x
30
46
60
73
89
97
118
129
153
Ultimate Limit State Axial Capacity (kN) Length (m)
2
3
4
5
6
7
8
9
10
11
12
13
14
602
1095
1444
1875
2205
2567
3030
3345
4040
417
902
1213
1672
1989
2368
2804
3151
3826
259
695
963
1431
1719
2119
2533
2942
3578
146
511
734
1182
1445
1849
2226
2692
3274
363
544
949
1178
1575
1922
2417
2956
250
401
751
948
1318
1627
2137
2625
165
292
588
758
1085
1363
1859
2296
209
457
606
892
1131
1603
1998
352
481
730
938
1378
1723
591
777
1175
1478
476
643
996
1271
381
529
842
1083
299
432
709
925
Notes:
The table shows Ultimate Limit State (maximum applied) axial load based on
BS5950-1:2000.
H sections are to be used with the web vertical.
Struts are assumed to be effectively pinned in plan and elevation
Allowance has been made for strut self weight and an accidental vertical
load of 10kN at the centre of the strut.
An allowance has been made for the axial load to act eccentrically at 10%
of the section depth.
Strut axial capacity is based on S275 material to EN10025.
For additional or alternate loading, or alternative material, calculations must
be made to establish the correct axial capacity.
Common Values
Sections must be class 1 or 2 with Low Shear
Gravity =
9.81 m/sec2
Accidental Load =
10kN
ULS Load Factors:
Steel self weight =
1.4
Live load =
1.6
Effective length factor =
1.0
Section type =
H
Grade =
S275
Chapter 7/24
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Table 7.12.3 Ultimate Capacity Table for Circular Hollow Section Struts
Circular Hollow
Section
Strut Size
5
6
8
CHS
273 x 10
1807 1645 1191
CHS 323.9 x 10
2294 2166 1825
CHS 355.6 x 12.5 3242 3106 2742
CHS 406.4 x 12.5 3829 3712 3401
CHS
457 x 12.7 4473 4367 4097
CHS
508 x 12.7 4783 4743 4653
CHS
559 x 14.3 5964 5923 5832
CHS
610 x 14.3 6554 6515 6428
CHS
660 x 15.9 7907 7867 7777
CHS
711 x 15.9 8559 8521 8434
CHS
762 x 17.5 9822 9783 9692
CHS
813 x 17.5 10518 10480 10391
CHS
864 x 20.6 13134 13093 12995
CHS
914 x 20.6 13935 13895 13799
Ultimate Limit State Axial Capacity (kN)
Length (m)
10
12
14
16
18
20
22
24
810
548
374
255
1359
986
715
522
382
2206 1657 1246
941
716
546
3001 2401 1865
1454 1137
893
704
554
3711 3245 2631
2099 1682
1350 1087
877
4392 3940 3378
2807 2303
1885 1544 1268
5666 5233 4662
4010 3376
2817 2347 1957
6326 5990 5491
4876 4215
3587 3035 2563
7672 7437 6952
6334 5616
4880 4195 3589
8331 8212 7787
7237 6569
5831 5098 4419
9584 9459 9180
8667 8035
7297 6508 5733
10285 10162 10012
9547 8975
8292 7524 6728
12877 12739 12581 12197 11585 10847 9993 9065
13682 13546 13389 13159 12596 11919 11123 10229
Notes:
The table shows Ultimate Limit State (maximum applied) axial load based on
BS5950-1:2000.
Allowance has been made for strut self weight and an accidental load of
10kN at the centre of the strut.
An allowance has been made for the axial load to act eccentrically at 10%
of the section diameter.
Strut axial capacity is based on S355 material to EN10210.
For additional or alternate loading, or alternative material, calculations must
be made to establish the correct axial capacity.
Common Values
Sections must be class 1, 2 or 3 with Low Shear
Gravity =
9.81m/sec2
Accidental Load =
10 kN
ULS Load Factors:
Steel self weight =
1.4
Live load =
1.6
Effective length factor =
1.0
Section type =
H
Grade =
S355
Slenderness ratio limit for l =
180
Chapter 7/25
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.13 Circular Cofferdams
Tables 1.13.5 and 1.14.5 in chapter 1 give the approximate
minimum diameters of cofferdams constructed in AZ, AU, PU, GU
and PU-R sheet piling.
The tables are intended as a guide since the minimum diameter
will depend upon several other factors such as type of ground,
length of piles and penetration required.
Smaller diameters can be achieved by introducing individual bent
piles.
On site it may be advantageous to pitch the whole circle before
driving, to ensure the circle can be closed, the piles being driven
in stages as the hammer works its way several times around the
circumference. However for larger circles, or when using a leader
rig, this may be impractical but great care will be needed to
ensure that the final piles close the ring without departing too far
from the required line.
Earth pressures are calculated as for straight-sided cofferdams
and circular ring beams, instead of walings and struts, may
support the piles leaving the central area clear of obstructions.
The ring beams will work in hoop compression and are thus
normally subjected to axial loads only which are calculated as
follows:
Axial load (kN) = waling load (kN/m) x radius of cofferdam (m)
Ring beams can be made from either steel or concrete. For steel
rings there are specialist fabricators that can roll large H and I
sections to the required radius the design of which should take in
to account the stiffness of the ring, using Timoshenko’s formula
described below, and the possibility of local flange instability.
The following table gives an indication of suitable sizes of
reinforced concrete ring beams for various cofferdam diameters
and loadings.
Chapter 7/26
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Table 7.13 Reinforced Concrete Walings for Circular Cofferdams
Diameter
of
Cofferdam
(metres)
5
10
15
20
25
30
35
40
45
50
450 x 300
6 no. 12ø
bars
852
376
164
Ultimate Waling Load (kN per metre run)
Size of Waling ‘d’ x ‘b’ in mm and number of reinforcing bars
600 x 400 750 x 500 900 x 600 1050 x 700 1200 x 800 1350 x 900 1450 x 950
10 no. 12ø 8 no. 16ø
8 no. 20ø 10 no. 20ø 8 no. 25ø 10 no. 25ø 8 no. 32ø
bars
bars
bars
bars
bars
bars
bars
1504
2328
752
1164
1690
501
776
1127
1520
1977
292
582
845
1140
1483
1875
457
676
912
1186
1500
1725
563
760
989
1250
1437
652
847
1071
1232
742
937
1078
833
958
862
Note:
The number and size of reinforcing bars given in the table is based on the
minimum area of steel for column construction given by table 3.25 of
BS8110-1: 1997 and assumes the use of High Yield Steel (fy = 460 N/mm2)
reinforcing bars to BS4449:1988
Fig 7.13
Tension Stay to
prevent torsion
in waling
Circular reinforced
concrete walings
x
Reinforced
concrete
waling
b
x
d
Steel sheet piling
Steel
sheet piling
Chapter 7/27
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.14 Reinforced concrete walings for circular Cofferdams
The tabulated ultimate waling loads are based on :
1. Ultimate load for concrete calculated in accordance with
BS8110-1:1997 clause 3.8.4.3 for C35 concrete and
reinforcement with fy = 460 N/mm2
2. W = 3EI
r 3109
where
W = waling load in kN/m
E = Young’s Modulus for concrete = 21000 N/mm2
I = Moment of Inertia about ‘x-x’ in mm4
r = Mean radius of ring beam in metres
3. The cofferdam diameter (D) divided by the width of the beam
(d) <35
The above formula is based on Timoshenko’s work wherein
the formula is given as:
Wu = kEI kN/m
r3109
Where Wu is the ultimate waling load and k is a factor, the value
of which is dependent on the stiffness of the retained medium
(3 is the value for water, eg in a marine cofferdam built to facilitate
construction on the sea bed). Progressively higher values are, in
theory, applicable for weak/medium/strong soils. However it is
common to use the value of 3 for all conditions. It is worth noting
that for the majority of the values in table 7.13 the load is
governed by the limiting column load from BS8110 and not by the
Timoshenko value which is higher. Increasing the reinforcement
may give increased loads up to the Timoshenko value.
The ring beam can tolerate very little distortion from a true circle
before the onset of catastrophic instability. Hence the empirical
rule:
D/d < 35
Where d is the width of the ring beam, ie the difference between
the inner and outer radii of the beam and D is the diameter of the
cofferdam (ie the diameter of the inner face of the piles). If the
sheet piles deflect to any great extent then the load in the walings
will be concentrated at the top or bottom of the waling and will
impart torsion into the beam. This condition should also be
checked in the design.
Chapter 7/28
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.15 Earth filled double-wall and cellular Cofferdams
Earth filled cofferdams are self supporting gravity structures,
either parallel-sided double-wall cofferdams or cellular
cofferdams. The stability of both types is dependent on the
properties of the fill and the soil at foundation level as well as on
the arrangement and type of the steel sheet piling. Typical uses
are as dams to temporarily seal off dock entrances so that work
below water level can be carried out in the dry and in the
construction of permanent walls for land reclamation, quays,
wharves and dolphins.
7.16 Double skin / wall Cofferdams
Double wall cofferdams comprise two parallel lines of sheet piles
connected together by a system of steel walings and tie rods at
one or more levels. The space between the walls is generally
filled with granular material such as sand, gravel, or broken rock.
The exposed or inner wall is designed as an anchored retaining
wall while the outer line of piles acts as the anchorage. U or Z
profile sheet piles are appropriate to this form of construction.
The wall as a whole should be analysed as a gravity structure
and, in order to achieve adequate factors of safety against
overturning and sliding, the width will generally be found to be not
less than 0.8 of the retained height of water or soil. It is
recommended that the overall stability of the structure is checked
using the logarithmic spiral method devised by Jelinek.
Transverse bulkheads should be provided to form strong points at
the ends and at intermediate positions to assist construction and
confine any damage that might occur. The strong points may
comprise a square or rectangular cell tied in both directions.
The water regime both inside and outside the structure is critical.
It is recommended that weepholes are provided on the inner side
of the structure near the bottom of the exposed portion of the
piles to permit free drainage of the fill material reducing the
pressures on the inner wall and preventing a decrease in the shear
strength of the fill with time. Weepholes are only effective for
small structures and complete drainage of the fill may not always
be practical. Wellpoints and pumping offer an alternative option
and will provide fast drainage if required. However the designer
should always make allowance for any water pressure acting on
the piles. It is essential that clay or silt is not used as fill material
and any material of this type, occurring above the main
foundation stratum, within the cofferdam must be removed prior
to fill being placed.
Chapter 7/29
Piling Handbook, 8th edition (revised 2008)
Cofferdams
The piles must be driven into the soil below excavation or dredge
level to a sufficient depth to generate the required passive
resistance. In this condition the structure will deflect towards the
excavated side and the lateral earth pressures on the retained
side may be taken as active. When cohesionless soils occur at or
below excavation level, the penetration of the piling must also be
sufficient to control the effects of seepage. The bearing capacity
of the founding stratum should be checked against the weight of
the structure and any superimposed loading.
The presence of rock at excavation level makes this type of
cofferdam unsuitable unless:
• The rock is of a type that will allow sheet piles to be driven into
it to an adequate penetration (see chapter 11).
• Tie rods can be installed at low level (probably underwater).
• A trench can be preformed in the rock into which the piles can
be placed and grouted.
• The pile toes can be pinned with dowels installed in sockets in
the rock.
If the piles are driven onto hard rock, or to a nominal depth below
dredged level, the resistance to overturning and sliding should be
developed by base friction and gravitational forces alone. In this
condition the lateral earth pressure on the retained side will be in
a condition between at rest and active, depending on the amount
of deflection.
The internal soil pressures acting on the outer walls are likely to
be greater than active due to the non uniform distribution of
vertical stresses within the cofferdam (due to the moment effects)
and hence the design should be based on pressures of 1.25 times
the active values.
7.17 Cellular Cofferdams
The design and construction of cellular cofferdams is discussed in
Chapter 9.
7.18 Effect of water pressure
The stability of a cofferdam can be adversely affected by the
action of water pressures on the soils at formation level to the
extent that collapse may occur. In granular soils excess water
pressure causes piping and in cohesive or very tightly packed
soils heave results.
Chapter 7/30
Piling Handbook, 8th edition (revised 2008)
Cofferdams
Piping occurs when the pressure on the soil grains due to the
upward flow of water is so large that the effective stress in the soil
approaches zero. In this situation the soil has no shear strength
and assumes a condition that can be considered as a quicksand,
which will not support any vertical load. This is obviously a very
dangerous situation for personnel operating in the cofferdam and
will also lead to a significant reduction in passive resistance
afforded to the cofferdam wall by the soil. In extreme cases this
can lead to a complete loss of stability of the wall and failure of
the cofferdam. The likelihood of piping for a given cross section
can be predicted by the construction of a flow net, which will
allow the engineer to calculate the exit hydraulic gradient.
Comparison of the calculated value to the critical hydraulic
gradient will indicate the factor of safety against piping; for clean
sands this should generally lie between 1.5 and 2.0. Care should
be taken when designing circular cofferdams and at the corners of
rectangular structures where the three dimensional nature of the
situation is more critical than in the case of a long wall.
The factor of safety against piping can be increased by installing
the piles to a greater depth thereby increasing the flow path length
and reducing the hydraulic gradient.
Table 7.18 Minimum cut-off depth
Width of Cofferdam
W
Depth of cut-off
D
2H or more
0.4H
H
0.5H
0.5H
0.7H
Fig 7.18 Minimum cut-off depth
GWL
W
H
D
Table 7.18 gives an approximate guide to the safe minimum cutoff depth for a cofferdam constructed in medium uniform
cohesionless soil when the toes of the piles do not penetrate
Chapter 7/31
Piling Handbook, 8th edition (revised 2008)
Cofferdams
impermeable soils and excess water is pumped from sumps at
excavation level.
Base heave can occur in cohesive or very tightly packed granular
material if the force exerted by the water pressure acting on a
block of material inside the cofferdam exceeds the bulk weight of
the block. The likelihood of heave can be assessed using a flow
net to calculate the average water pressure acting on the line
drawn between the toes of the piles and converting this to an
uplift force on the soil plug within the cofferdam.
The flow of water into a cofferdam may also be reduced by
lowering the ground water level by means of well points outside
the cofferdam. Alternatively, flow into the cofferdam can be
reduced by pumping from well points located inside the cofferdam
at or below the pile toe level. It should however be remembered
that, when the stability or ease of operation of a cofferdam
involves pumping, reliability of the pumps is of paramount
importance and back-up capacity must be available to cope with
any emergencies.
Chapter 7/32
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.19 Flow nets
The preparation of flow nets is a useful tool, as it not only allows
the engineer to calculate the water pressures in a particular
situation, but also provides a visual representation of the flow
regime in the soil.
Fig 7.19
C
B/2
Gravel
(very permeable)
B/2
Standpipe Piezometer
(water level at point A)
Water table
Gravel
sand
Flow lines
Sand
1
U/δw
10
9
8
7
H1
C
H2
Equipotential
lines
A
H
2
B
6
3
5
Z
4
Datum impermeable base stratum
Head at
point A
The shape and complexity of a flow net is a function of the
homogeneity and permeability of the soil and the following notes
indicate how a net can be drawn for uniform soil conditions and
permeability.
• A scaled cross section drawing of the problem should be
produced.
• A datum level should be marked on the cross section either at
an impermeable boundary or at a suitable level below the
cofferdam.
• The flow criteria must be determined.
• External water level.
• Internal water level.
• Centre line of cofferdam (this is the axis of symmetry).
• Lines of flow must be parallel to the cofferdam walls and the
impervious datum.
Using the above as guidelines, the net is produced from flow lines
and equipotential lines (a stand pipe at any point on an
equipotential line would register the same height H above the
datum level). These are at right angles to each other and form
Chapter 7/33
Piling Handbook, 8th edition (revised 2008)
Cofferdams
approximate squares. This process is very much trial and error
but practice will enable the flow net to be produced with a
reasonable degree of speed and accuracy.
To calculate the pore water pressure ‘u’ at any point (using the
example above)
• Calculate the potential head ‘H’ at the desired point (note that
the potential head drop is always the same between
successive equipotential lines once a square net has been
formed)
n
H = H1 -(H1 - H2) .
Nd
where
n = number of equipotential drops to the point being considered
Nd = total number of drops
Hence at point A,
2
H = H1 -(H1 - H2) .
10
• At any point H = u + z
γw
where
u = pore water pressure
γw = density of water
z = height of point above datum
As H, γw and z are known, u can be calculated,
u = (H - z) . γw
Flow nets can also be used to estimate the approximate volume
of water flowing around the toes of the piles into the cofferdam.
The flow volume ‘Q’ m3/s per metre run of wall is given by
N
Q = k (H1 - H2) . f
Nd
where
k = coefficient of permeability of the ground (m/s)
H1 - H2 = total head drop (m)
N f = number of flow channels (in half width of cofferdam)
Nd = number of potential drops
Chapter 7/34
Piling Handbook, 8th edition (revised 2008)
Cofferdams
7.20 Factor of safety against piping
The flow net allows the calculation of the ‘exit hydraulic gradient’
just below the formation level inside the cofferdam. Hydraulic
gradient ‘i’ is defined as loss of head per unit length in the
direction of flow, which is a dimensionless number. In the
example above, the exit gradient ie is given by
H - H2 ) . ( 2Nf )
ie = ( 1
Nd
B
where
B/2Nf is the width of each exit flow net square
since
B/2 is the half width of the cofferdam
Nf is the number of flow channels in the half width of the
cofferdam
For ground with a saturated bulk weight of approximately 20
kN/m3 the critical hydraulic gradient at which the effective soil
stress reduces to zero and piping occurs will be ic = 1.0. The
factor of safety against piping is defined as
FoS =
ic
1.0
, which approximates to
ie
ie
A flow net such as the example is strictly a slice from a very long
cofferdam. For square or circular cofferdams, the 3-dimensional
nature of the flow has the effect of further concentrating the head
loss within the soil plug between the sheet pile walls. The
following correction factors should be applied to the head loss per
field on the inside face of the cofferdam:
Circular cofferdams
parallel wall values x 1.3
In the corners of a square cofferdam
parallel wall values x 1.7
1.0
For clean sands the factor of safety against piping
ie
should be between 1.5 and 2.0
7.21 Pump sumps
Although a sheet pile wall can prevent the ingress of water into an
excavation, it is not possible to give any guarantee that a
cofferdam will be watertight. In order to deal with any water that
enters the excavation it is often desirable to install a drainage
system that can channel water to a sump from which water can
be pumped away.
As the hydraulic gradient adjacent to the corner of a cofferdam is
at its largest, it is advisable to place any sumps at excavation
level as far as possible from any corner and wall.
Chapter 7/35
Piling Handbook, 8th edition (revised 2008)
Cofferdams
It should not be forgotten that pumps are able to remove soil as
well as water and a suction hose laid in the bottom of a cofferdam
can disturb the base of the excavation with subsequent
movement of the wall if the hose is badly located. Consideration
should be given to forming a sump using a perforated drum into
which the hose can be fixed to limit damage.
7.22 Sealants
Chapter 7/36
While cofferdams on land will generally have sufficient soil within
the interlocks to restrict the flow of water the use of sealants
should not be discounted. In open granular soils particularly a
suitable sealant in the interlock may restrict the volume of water
entering the cofferdam such that the reduction in pumping costs
will be significantly greater than the initial cost of the sealant. For
cofferdams in water the problem of sealing a cofferdam that is
leaking badly is such that it is advisable to use a sealant as a
matter of course. If it does prove necessary to attempt to seal a
cofferdam, post construction, then the traditional method is to use
a mixture of ashes and sawdust dropped in the water on the
outside where it, hopefully, will be sucked into the leaking
interlocks and form a seal. If access to the outside is not feasible,
for instance in a cofferdam on land, then the sealing has to be
carried out from the inside using either a mastic putty or some
other form of malleable caulking product. The main problem with
sealing on the inside will always be preventing the water pressure
from pushing the sealant out. It is essential, therefore, that to
obtain the best results, the sealing material is forced as far as
possible into the interlock and certainly beyond the corner radii.
Charts for
retaining walls
8
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Contents
Page
8.1
Typical retaining walls
Cantilever
Cantilever
Cantilever
Tied
Tied
Tied
Cantilever
Cantilever
Tied
Tied
Water condition A
Water condition B
Water condition C
Water condition A
Water condition B
Water condition C
Water condition C
Water condition D
Water condition C
Water condition D
1
φ = 40°
5
φ = 30°
6
φ = 20°
7
φ = 40°
8
φ = 30°
9
φ = 20°
10
φ = 40°
11
φ = 30°
12
φ = 20°
13
φ = 40°
14
φ = 30°
15
φ = 20°
16
φ = 40°
17
φ = 30°
18
φ = 20°
19
φ = 40°
20
φ = 30°
21
φ = 20°
22
Su = 75kN/m2
23
2
Su = 40kN/m
24
Su = 75kN/m2
25
2
Su = 40kN/m
26
Su = 75kN/m2
27
2
Su = 40kN/m
28
Su = 75kN/m2
29
2
30
Su = 40kN/m
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
8.1 Typical retaining walls
The following charts indicate the structural requirements for a
retaining wall operating in the conditions specified. As the range of
possible design conditions is vast, a simplified set of parameters
has been chosen which illustrate the effect of change of soil
strength, water regime and support conditions. While it is not
intended that these charts should be used as a substitute for
actual design for a set of circumstances they may be useful when
assessing the likely requirements for a project at project appraisal
stage.
The soil parameters referenced in these examples are assumed to
be the representative values for the soil which are then factored
before carrying out the design calculations.
The user should select the conditions which represent the case in
question and then read off the minimum section modulus by steel
grade, the support force if appropriate and minimum pile length
from the charts. The values thus obtained should be regarded as
ultimate loads and equated to the ultimate capacity of the walings
etc.
The charts are based on the assumption that weep holes are
provided where necessary and the retained soil is capable of
allowing the design water regime to be realised. In the case of
cohesive soils, the charts allow for the accumulation of ground
water in any tension cracks which may develop.
The length of pile below excavation level has not been checked to
ensure that there is sufficient penetration to prevent piping or
heave. This must be considered separately.
Note:
Cantilever walls in excess of about 4.5m to 5m high are not
generally recommended as the section required to resist bending
moments and the length required for stability mean that
uneconomic designs may result. In circumstances where the
retained height exceeds 4.5m, a cantilever wall may be
considered, but the deflection of the wall is likely to be large and
this should be checked to ensure that serviceability criteria are not
exceeded. This caveat should not be seen as a limitation on the
use of steel sheet piling as much of the deflection on a cantilever
wall results from soil movements and is therefore applicable to
walls formed in any material.
It is further recommended that cantilever walls in soft clays are
considered with extreme care and that they should not be
designed for permanent construction using total stress soil
parameters.
When U profile sheet piles are selected for the construction of
cantilever retaining walls, the designer must satisfy himself that the
section is capable of developing the required section modulus.
Guidance on the selection of pile sections is given in Chapter 1.
Chapter 8/1
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
The parameters below have been adopted in the following typical
examples:
Table: 8.1
Unfactored soil
strength
parameter
γ
(kN/m3)
γ'
(kN/m3)
δ
(Both
sides)
Sw/Su
Ka
Kac
Kp
Kpc
φ' = 40°
20.5
18.1
2/3 φ
-
0.229
-
6.493
-
φ' = 30°
19.1
14.7
2/3 φ
-
0.343
-
3.554
-
φ' = 20°
18.6
18.6
2/3 φ
-
0.494
-
2.193
-
Su = 75 kN/m2
19.6
19.6
-
0.5
1
2.449
1
2.449
Su = 40 kN/m2
18.6
18.6
-
0.5
1
2.449
1
2.449
γ w= 9.81kN/m3
The following water conditions have been adopted.
Water condition A:
Ground water at the top of the piles on the active side and at
excavation level on the passive side.
Fig 8.1 Cantilever - water condition A
Fig 8.2 Tied - water condition A
Surcharge = 10 kN/m 2
Surcharge = 10 kN/m
GWL.
2
GWL.
d
H
H
L
L
GWL.
GWL.
Water condition B:
Ground water at excavation level on the both sides of the wall.
Fig 8.3 Cantilever -water condition B
2
Fig 8.4 Tied - water condition B
Surcharge = 10 kN/m
Surcharge = 10 kN/m
2
d
H
H
L
GWL.
Chapter 8/2
GWL.
GWL.
L
GWL.
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Water condition C:
No ground water is assumed in this case
Fig 8.5 Cantilever - water condition C
Surcharge = 10 kN/m2
Fig 8.6 Tied - water condition C
Surcharge = 10 kN/m2
d
H
H
L
L
Water condition D:
Active water to the top of the piles and passive water at
excavation level. Soil is at the passive water level on both sides.
Fig 8.7 Cantilever - water condition D
Fig 8.8 Supported - water condition D
WL.
WL.
d
H
H
L
L
GWL.
GWL.
Details of sheet pile products and steel grades are given in
chapter 1.
Chapter 8/3
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Using the plots. (refer to Fig. 8.9 example plot)
1
Select the plot appropriate to the particular conditions under review.
2
For a given retained height, excluding any allowance for overdig, draw a vertical line to
intersect with the lines on both the upper and lower plots.
3
Draw a horizontal line from the intersection point with the solid line on the lower plot to the
right hand vertical axis to obtain the overall pile length.
4
Draw a horizontal line from the intersection point with one of the dashed lines (dependant
on selected steel grade) to the left hand vertical axis to obtain the minimum section
modulus.
5
Draw a horizontal line from the intersection point with the line on the upper plot to the left
hand vertical axis to obtain the support load.
6
Tie load and Section modulus values obtained from these charts include the factors
recommended in chapters 5 and 6.
4
5
6
10
11
12
1000
800
T=410kN/m
600
< < < < < <
0
16000
10000
8000
6000
4000
Z=1850 cm3/m
2000
< < < < < <
20.0
17.5
15.0
12.5
L=11m
10.0
7.5
5.0
2.5
0.0
0
4
5
S270GP
Chapter 8/4
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Wall length (m)
200
< < < < < < < < < < <
400
12000
Section modulus (cm3/m)
φ = 40°
1200
14000
The charts indicate the
section modulus required
for steel grades S270GP,
S355GP and S430GP.
The requirements for
alternative steel grades
can be determined by
looking up the modulus
needed for a given set of
conditions, multiplying the
number by either 270, 355
or 430 depending on
which plot has been used
and dividing the result by
the yield strength of the
proposed steel.
Retained height (m)
7
8
9
< < < < < < < < < < < < < < < < < < < < <
Factored tie load (kN/m)
Fig. 8.9 Example plot
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
4000
16
3500
14
3000
12
2500
10
2000
8
1500
6
1000
4
500
2
Wall length (m)
φ = 40°
Fig. 8.10 Cantilever - Water condition A
0
0
1
1.5
S270GP
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Chapter 8/5
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
8000
20
7000
17.5
6000
15
5000
12.5
4000
10
3000
7.5
2000
5
1000
2.5
0
0
1
1.5
S270GP
Chapter 8/6
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Wall length (m)
φ = 30°
Fig. 8.11 Cantilever - Water condition A
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
18000
30
15000
25
12000
20
9000
15
6000
10
3000
5
0
Wall length (m)
φ = 20°
Fig. 8.12 Cantilever - Water condition A
0
1
1.5
S270GP
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Chapter 8/7
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
1000
10.0
900
9.00
800
8.00
700
7.00
600
6.00
500
5.00
400
4.00
300
3.00
200
2.00
100
1.00
0.00
0
1
1.5
S270GP
Chapter 8/8
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Wall length (m)
φ = 40°
Fig. 8.13 Cantilever - Water condition B
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
2000
15.00
1800
13.50
1600
12.00
1400
10.50
1200
9.00
1000
7.50
800
6.00
600
4.50
400
3.00
200
1.50
Wall length (m)
φ = 30°
Fig. 8.14 Cantilever - Water condition B
0.00
0
1
1.5
S270GP
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Chapter 8/9
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
8000
24.0
7000
21.0
6000
18.0
5000
15.0
4000
12.0
3000
9.00
2000
6.00
1000
3.00
0
0
1
1.5
S270GP
Chapter 8/10
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Wall length (m)
φ = 20°
Fig. 8.15 Cantilever - Water condition B
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
900
9.00
800
8.00
700
7.00
600
6.00
500
5.00
400
4.00
300
3.00
200
2.00
100
1.00
0
1
1.5
S270GP
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
Wall length (m)
φ = 40°
Fig. 8.16 Cantilever - Water condition C
0
4.5
Length
Chapter 8/11
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
1800
12.00
1500
10.00
1200
8.00
900
6.00
600
4.00
300
2.00
0.00
0
1
1.5
S270GP
Chapter 8/12
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Wall length (m)
φ = 30°
Fig. 8.17 Cantilever - Water condition C
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Section modulus (cm3/m)
4500
18.00
4000
16.00
3500
14.00
3000
12.00
2500
10.00
2000
8.00
1500
6.00
1000
4.00
500
2.00
0
1
1.5
S270GP
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
Wall length (m)
φ = 20°
Fig. 8.18 Cantilever - Water condition C
0
4.5
Length
Chapter 8/13
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 40°
4
5
6
Retained height (m)
7
8
9
10
11
12
1200
1000
800
600
400
200
0
16000
20.0
14000
17.5
12000
15.0
10000
12.5
8000
10.0
6000
7.5
4000
5.0
2000
2.5
0.0
0
4
5
S270GP
Chapter 8/14
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.19 Tied - Water condition A (d=1.5m)
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 30°
4
5
6
Retained height (m)
7
8
9
10
11
12
2000
1500
1000
500
0
30000
30.0
25000
25.0
20000
20.0
15000
15.0
10000
10.0
5000
5.0
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.20 Tied - Water condition A (d=1.5m)
0
0
4
5
S270GP
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Chapter 8/15
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 20°
Factored tie load (kN/m)
Fig. 8.21 Tied - Water condition A (d=1.5m)
4
5
6
Retained height (m)
7
8
9
10
11
12
3000
2500
2000
1500
1000
500
0
60,000
36.0
34.0
32.0
50,000
30.0
Section modulus (cm3/m)
26.0
24.0
30,000
22.0
20,000
20.0
18.0
10,000
16.0
14.0
0
12.0
4
5
S270GP
Chapter 8/16
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Wall length (m)
28.0
40,000
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 40°
4
5
6
Retained height (m)
7
8
9
10
11
12
400
300
200
100
0
4000
20
3600
18
3200
16
2800
14
2400
12
2000
10
1600
8
1200
6
800
4
400
2
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.22 Tied - Water condition B (d=1.5m)
0
0
4
5
6
S270GP
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Chapter 8/17
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 30°
4
5
6
Retained height (m)
7
8
9
10
11
12
800
700
600
500
400
300
200
100
0
7000
28.0
6000
24.0
5000
20.0
4000
16.0
3000
12.0
2000
8.0
1000
4.0
0.0
0
4
5
S270GP
Chapter 8/18
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.23 Tied - Water condition B (d=1.5m)
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 20°
4
5
6
Retained height (m)
7
8
9
10
11
12
1800
1600
1400
1200
1000
800
600
400
200
0
30000
30.0
25000
25.0
20000
20.0
15000
15.0
10000
10.0
5000
5.0
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.24 Tied - Water condition B (d=1.5m)
0
0
4
5
S270GP
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Chapter 8/19
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 40°
4
5
6
Retained height (m)
7
8
9
10
11
12
400
300
200
100
0
3500
17.5
3000
15.0
2500
12.5
2000
10.0
1500
7.5
1000
5.0
500
2.5
0.0
0
4
5
S270GP
Chapter 8/20
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.25 Tied - Water condition C (d=1.5m)
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 30°
4
5
6
Retained height (m)
7
8
9
10
11
12
800
700
600
500
400
300
200
100
0
6000
24.0
5000
20.0
4000
16.0
3000
12.0
2000
8.0
1000
4.0
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.26 Tied - Water condition C (d=1.5m)
0.0
0
4
5
S270GP
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Chapter 8/21
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
φ = 20°
4
5
6
Retained height (m)
7
8
9
10
11
12
1200
1000
800
600
400
200
0
16000
22.0
14000
20.0
12000
18.0
10000
16.0
8000
14.0
6000
12.0
4000
10.0
2000
8.0
6.0
0
4
5
S270GP
Chapter 8/22
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Wall length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.27 Tied - Water condition C (d=1.5m)
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Su = 75kN/m2
1400
14.0
1200
12.0
1000
10.0
800
8.00
600
6.00
400
4.00
200
2.00
0
1
1.5
S270GP
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
Pile length (m)
Section modulus (cm3/m)
Fig. 8.28 Cantilever - Water condition C
0.00
4.5
Length
Chapter 8/23
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Su = 40kN/m2
2500
25.0
2000
20.0
1500
15.0
1000
10.0
500
5.00
Pile length (m)
Section modulus (cm3/m)
Fig. 8.29 Cantilever - Water condition C
0.00
0
1
1.5
S270GP
Chapter 8/24
2
2.5
3
3.5
Retained height (m)
S355GP
4
S430GP
4.5
5
Length
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Su = 75kN/m2
1200
12.00
1000
10.00
800
8.00
600
6.00
400
4.00
200
2.00
Wall length (m)
Section modulus (cm3/m)
Fig. 8.30 Cantilever - Water condition D
0.00
0
1
1.5
S270GP
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Chapter 8/25
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
Su = 40kN/m2
1600
16.0
1400
14.0
1200
12.0
1000
10.0
800
8.00
600
6.00
400
4.00
200
2.00
0.00
0
1
1.5
S270GP
Chapter 8/26
2
2.5
3
Retained height (m)
S355GP
3.5
S430GP
4
4.5
Length
Wall length (m)
Section modulus (cm3/m)
Fig. 8.31 Cantilever - Water condition D
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
4
5
6
Retained height (m)
7
8
9
Su = 75kN/m2
10
11
800
700
600
500
400
300
200
100
0
8000
40.0
7000
35.0
6000
30.0
5000
25.0
4000
20.0
3000
15.0
2000
10.0
1000
5.00
Pile length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.32 Tied - Water condition C (d=1.2m)
0.00
0
4
5
S270GP
6
7
8
Retained height (m)
S355GP
9
S430GP
10
11
Length
Chapter 8/27
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
4
4.5
Retained height (m)
5.0
(d = 1.2m)
5.5
Su = 40kN/m2
6
350
300
250
200
150
100
50
0
2000
40.0
1800
36.0
1600
32.0
1400
28.0
1200
24.0
1000
20.0
800
16.0
600
12.0
400
8.00
200
4.00
0.00
0
4
4.5
S270GP
Chapter 8/28
5.0
Retained height (m)
S355GP
5.5
6
S430GP
Length
Pile length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.33 Tied - Water condition C
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
4
5
6
Retained height (m)
7
8
(d=1.2m)
9
10
Su = 75kN/m2
11
12
700
600
500
400
300
200
100
0
8000
40.0
7000
35.0
6000
30.0
5000
25.0
4000
20.0
3000
15.0
2000
10.0
1000
5.00
Pile length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.34 Tied - Water condition D
0.00
0
4
5
S270GP
6
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Chapter 8/29
Piling Handbook, 8th edition (revised 2008)
Charts for retaining walls
4
5
6
Retained height (m)
7
8
9
10
Su = 40kN/m2
11
12
1200
1000
800
600
400
200
0
20000
40.00
18000
36.00
16000
32.00
14000
28.00
12000
24.00
10000
20.00
8000
16.00
6000
12.00
4000
8.00
2000
4.00
0.00
0
4
5
6
S270GP
Chapter 8/30
7
8
9
Retained height (m)
S355GP
10
S430GP
11
12
Length
Pile length (m)
Section modulus (cm3/m)
Factored tie load (kN/m)
Fig. 8.35 Tied - Water condition D (d=1.2m)
Circular cell
construction
9
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
Contents
Page
9.1
Introduction
1
9.2
Straight web piling
1
Dimensions and properties for AS 500
straight web piles
1
9.3
9.4
Interlock strength
Junction piles
2
3
9.5
Types of cell
3
9.6
Bent piles
3
9.7
Equivalent width and ratio
4
9.8
Geometry
5
9.8.1
Circular cells
5
9.8.2
Diaphragm cells
6
Handling straight web piles
7
9.2.1
9.9
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
9.1 Introduction
Cellular cofferdams are self-supporting gravity structures constructed
using straight web sheet piles to form various shapes. The piles are
interlocked and driven to form closed cells which are then filled with
cohesionless material. To achieve continuity of the wall, the circular
cells are connected together using fabricated junction piles and short
arcs.
Provided that the material on which they are to be founded is solid
they require only nominal penetration to be stable. Pile penetration
will assist in the resistance of any lateral loads occurring during the
construction phase in the vulnerable period before the fill has been
placed and the cell has become inherently stable.
Cellular cofferdam structures are used to retain considerable depths
of water or subsequently placed fill. They are commonly used as
dock closure cofferdams, or to form quay walls and breakwaters. The
straight web pile section and particularly the interlocks have been
designed to resist the circumferential tension which is developed in
the cells due to the radial pressure of the contained fill and at the
same time permit sufficient angular deflection to enable cells of a
practical diameter to be formed. In cellular construction no bending
moments are developed in the sheet piles which enables the steel to
be disposed in such a manner that the maximum tensile resistance is
developed across the profile. The sections have therefore very little
resistance to bending and are not suitable for normal straight sheet
pile wall construction. Walings and tie rods are not required.
The design and construction of cellular cofferdams is very complex
and further information is available from our Technical Department.
Chapter 9/1
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
9.2 Straight web piling
Table 9.2 Tolerances for straight web piles to EN 10248 Part 2
Tolerances
Mass
Length
Height
Thickness
Width single pile
Width double pile
Straightness
Ends out of square
AS 500
±5%
±200mm
t, s > 8.5mm: ±6%
±2%
±3%
0.2% of the length
2% of pile width
9.2.1 Dimensions and properties for AS 500 Straight Web piles
Fig 9.2.1
finger
t
δ
thumb
b
~ 92mm
Table 9.2.1
Section
AS
AS
AS
AS
AS
500-9,5
500-11,0
500-12,0
500-12,5
500-12,7
Nominal
Web
Deviation PeriSteel
Mass per
width* thickness
angle meter of section
m of a
a single
of a
single
pile
single
pile
pile
δ
b
t
mm
mm
°
cm
cm2
kg/m
500
500
500
500
500
9.5
11.0
12.0
12.5
12.7
4.5**
4.5**
4.5**
4.5**
4.5**
138
139
139
139
139
81.3
90.0
94.6
97.2
98.2
63.8
70.6
74.3
76.3
77.1
Mass
per m2
of wall
Moment Section
of inertia modulus
of a single pile
Coating
area***
kg/m2
cm4
cm3
m2/m
128
141
149
153
154
168
186
196
201
204
46
49
51
51
51
0.58
0.58
0.58
0.58
0.58
Note: all straight web sections interlock with each other.
* The effective width to be taken into account for design purposes (lay-out) is 503 mm for all AS 500 sheet piles.
** Max. deviation angle 4.0° for pile length > 20 m.
*** On both sides, excluding inside of interlocks.
9.3 Interlock strength
The interlock complies with EN 10248. Following interlock strength
Fmax can be achieved with a steel grade S 355 GP. However,
higher steel grades are available.
Sheet pile
AS 500 - 9.5
AS 500 - 11.0
AS 500 - 12.0
AS 500 - 12.5
AS 500 - 12.7
Fmax [kN/m]
3,000
3,500
5,000
5,500
5,500
For verification of the strength of piles, both yielding of the web and failure
of the interlock should be considered. The allowable tension force T in the
pile may be obtained by applying a safety factor, for example:
1__
T = ___
η R.
Chapter 9/2
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
The magnitude of the safety factor depends on the calculation method
and assumptions, the installation method and the function of the
structure. When two different sections are used in the same section of
wall, the lowest allowable tension force is to be taken into account. The
value of η = 2.0 is currently used.
9.4 Junction piles
In general junction piles are assembled by welding in accordance
with EN 12063.
Fig 9.4
2
b_
2
b_
120°
θ
θ
b_
2
b_
2
b_
2
BI
b_
2
150mm
BP
Y
The connecting angle θ should be in the range from 30° to 45°.
9.5 Types of cell
Fig 9.5
Circular cells with 35° junction piles and
one or two connecting arcs.
9.6 Bent piles
Diaphragm cells with 120° junction piles.
If deviation angles exceeding the values given in table 9.2.2 have
to be attained, piles pre-bent in the mill may be used.
Fig 9.6
β
CI
β
CP
Chapter 9/3
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
9.7 Equivalent width and ratio
Fig 9.7
The equivalent width we which is required for stability verification, determines the geometry of
the chosen cellular construction.
Circular cell with 2 arcs
Development
we =
Equivalent
width we
• for circular cells
Area within 1 cell + Area within 2 (or 1) arc(s)
System length x
shown on tables indicates how economical
System length x
Area
Circular cell with 1 arc
Development 1 cell + Development 2 (or 1) arc(s)
Ratio =
Development 1 cell + Development 2 (or 1) arc(s)
Equivalent
width we
The ratio shown on tables indicates how economical
the chosen circular cell will be.
System length x
c
System length x
x=r
120°
c
we = diaphragm wall length (dl) + 2 . c
r
60°
dl
we
• for diaphragm cells
120°
Chapter 9/4
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
9.8 Geometry
9.8.1 Circular cells
Once the equivalent width has been determined, the geometry of
the cells is to be defined. This can be done with the help of tables
or with computer programs. Several solutions are possible for
both circular and diaphragm cells with a given equivalent width.
Fig 9.8.1
b/
2
θ
dy
L
N
ra
θ = 35˚
rm
S
α
b/2
S
b/2
Standard Solution
we
M
α
M
S
S
β
L
A
x
Description:
= radius of the main cell
rm
ra
= radius of the connecting arcs
θ
= angle between the main cell and
the connecting arc
x
= system length
= positive or negative offset between
dy
the connecting arcs and the tangent
planes of the main cells
we = equivalent width
Junction piles with angles θ between 30° and 45°, as well as θ = 90°, are
possible on request. The following table shows a short selection of solutions
for circular cells with 2 arcs and standard junction piles with θ = 35°.
Table 9.8.1
Number of piles per
Cell
Geometrical values
Interlock
deviation
cell
arc
Arc System
L
M
S
N
pcs. pcs. pcs. pcs. pcs. pcs.
d=2·rm
m
ra
m
x
m
dy
m
100
104
108
112
116
120
124
128
132
136
140
144
148
152
156
160
164
168
172
176
180
184
188
16.01
16.65
17.29
17.93
18.57
19.21
19.85
20.49
21.13
21.77
22.42
23.06
23.70
24.34
24.98
25.62
26.26
26.90
27.54
28.18
28.82
29.46
30.10
4.47
4.88
4.94
4.81
4.69
5.08
5.14
5.55
5.42
5.82
5.71
5.76
5.99
6.05
5.94
6.33
6.72
7.12
7.00
7.06
7.46
7.35
7.74
22.92
24.42
25.23
25.25
25.27
26.77
27.59
29.09
29.11
30.61
30.62
31.45
32.13
32.97
32.98
34.48
35.98
37.48
37.49
38.32
39.82
39.83
41.33
0.16
0.20
0.54
0.33
0.13
0.16
0.50
0.53
0.33
0.36
0.17
0.50
0.00
0.34
0.15
0.17
0.20
0.23
0.03
0.37
0.40
0.20
0.23
33
35
37
37
37
39
41
43
43
45
45
47
47
49
49
51
53
55
55
57
59
59
61
15
15
15
17
19
19
19
19
21
21
23
23
25
25
27
27
27
27
29
29
29
31
31
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
4
25
27
27
27
27
29
29
31
31
33
33
33
35
35
35
37
39
41
41
41
43
43
45
150
158
162
166
170
178
182
190
194
202
206
210
218
222
226
234
242
250
254
258
266
270
278
α
β
δm
δa
°
28.80
27.69
26.67
28.93
31.03
30.00
29.03
28.13
30.00
29.12
30.86
30.00
31.62
30.79
32.31
31.50
30.73
30.00
31.40
30.68
30.00
31.30
30.64
°
167.60
165.38
163.33
167.86
172.07
170.00
168.06
166.25
170.00
168.24
171.71
170.00
173.24
171.58
174.62
173.00
171.46
170.00
172.79
171.36
170.00
172.61
171.28
°
3.60
3.46
3.33
3.21
3.10
3.00
2.90
2.81
2.73
2.65
2.57
2.50
2.43
2.37
2.31
2.25
2.20
2.14
2.09
2.05
2.00
1.96
1.91
°
6.45
5.91
5.83
6.00
6.15
5.67
5.60
5.20
5.31
4.95
5.05
5.00
4.81
4.77
4.85
4.55
4.29
4.05
4.11
4.08
3.86
3.92
3.72
Design values
2 arcs 2 arcs
we
m
ratio
13.69
14.14
14.41
15.25
16.08
16.54
16.82
17.27
18.10
18.56
19.39
19.67
20.67
20.95
21.76
22.23
22.69
23.15
23.98
24.26
24.72
25.54
26.00
3.34
3.30
3.27
3.35
3.42
3.38
3.35
3.32
3.39
3.35
3.42
3.39
3.44
3.42
3.48
3.44
3.41
3.38
3.43
3.41
3.39
3.43
3.41
Chapter 9/5
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
9.8.2 Diaphragm cells
Fig 9.8.2
Standard Solution
dy
c
θ
150
M
60°
θ = 120°
r
we
N
dl
Description:
r
= radius
θ
= angle between the arc and
the diaphragm
we = equivalent width, with we = dl+2 · c
dy = arc height
dl
= diaphragm wall length
x
= system length
c
x=r
The two parts of the following table should be used separately
depending on the required number of piles for the diaphragm wall
and the arcs.
Table 9.8.2
Geometry of the diaphragms
Number of
piles
Wall length
N
dl
m
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
53
55
Chapter 9/6
5.83
6.84
7.85
8.85
9.86
10.86
11.87
12.88
13.88
14.89
15.89
16.90
17.91
18.91
19.92
20.92
21.93
22.94
23.94
24.95
25.95
26.96
27.97
Geometry of the arcs
Number of
piles
System length
M
x
m
11
13
15
17
19
21
23
25
27
29
31
33
35
37
39
41
43
45
47
49
51
53
55
5.57
6.53
7.49
8.45
9.41
10.37
11.33
12.29
13.26
14.22
15.18
16.14
17.10
18.06
19.02
19.98
20.94
21.90
22.86
23.82
24.78
25.74
26.70
Interlock
deviation arc
Arc height
dy
m
c
m
δa
0.75
0.87
1.00
1.13
1.26
1.39
1.52
1.65
1.78
1.90
2.03
2.16
2.29
2.42
2.55
2.68
2.81
2.93
3.06
3.19
3.32
3.45
3.58
0.51
0.59
0.68
0.77
0.86
0.94
1.03
1.12
1.20
1.29
1.38
1.46
1.55
1.64
1.73
1.81
1.90
1.99
2.07
2.16
2.25
2.33
2.42
5.17
4.41
3.85
3.41
3.06
2.78
2.54
2.34
2.17
2.03
1.90
1.79
1.69
1.60
1.52
1.44
1.38
1.32
1.26
1.21
1.16
1.12
1.08
°
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
9.9 Handling straight web piles
Unlike piles designed to resist bending moments, straight-web
sheet piles have low flexural stiffness, which means that care must
be taken over their handling.
Incorrect storage could cause permanent deformation, making
interlock threading difficult if not impossible. It is therefore vital to
have a sufficient number of wooden packing pieces between each
bundle of stacked sheet piles, and to position these pieces above
each other to limit the risk of deformation.
g
g
p
Fig 9.9a Storage of straight-web sheet piles
Wood packing h=70mm
c
a
b
b
a
max. bundle weight: 7.5 tonnes
Overhang "a" less than 1.5 m
Spacing of packings "b" less than 4.0 m
Offset of bundle "c" not less than 0.15 m
Wood packings to be aligned in the vertical plane
Fig 9.9b Storage and handling
of straight-web sheet piles
Chapter 9/7
Piling Handbook, 8th edition (revised 2008)
Circular cell construction design & installation
When sheet piles have to be moved from the horizontal storage
position to another storage location, lifting beams or brackets
made from pile sections threaded into the interlocks prior to lifting
should be used.
When pitching piles up to 15 m long into the vertical position, only
one point of support near the top (the handling hole) is necessary.
Straight-web sheet piles more than 15 m long should be lifted at
two or even three points, in order to avoid plastic distortion.
Fig 9.9c Lifting of long straight-web sheet piles
a
a
b
0.15 L
0.40 L
0.45 L
L
a = points of support
b = fastening in the handling hole
b
lifting operation
Chapter 9/8
b
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Bearing & axially
loaded sheet piles
10
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
Contents
Page
10.1
Introduction
1
10.2
Types of load bearing piles
2
10.3
Design
3
10.3.1
General
3
10.3.2
Determination of effective length
4
10.3.3
Vertical load capacity
4
10.3.4
Piles subjected to tensile forces
10.3.5
Lateral load
10
10.3.6
Pile groups
10
10.3.7
Negative skin friction
10
10.3.8
9
Set up
10
10.4
Testing the load capacity of steel bearing piles
11
10.5
Welding of steel piles
12
10.6
Installation of bearing piles
13
10.7
Driving shoes
13
10.8
Axially loaded sheet piles
13
10.9
Steel sheet piling in bridge abutments
13
10.10
Integral bridge abutments
14
10.11
Steel sheet piles in basements
14
10.12
Load bearing sheet piles
15
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
10.1 Introduction
Steel sections can be used as bearing piles where soil and ground
conditions preclude the use of shallow foundations. They transmit
vertical loads from the structure through the upper soft layers to
ground of adequate strength for support. Steel sheet piles can be
used as simple bearing piles and have the added advantage that
they can be designed as a retaining wall that carries vertical loads.
The main advantages that steel piles have over alternative systems
are as follows:
• They are available in a wide range of profiles and section weights to
allow the most economical choice of section for any particular
loading condition or soil profile.
• They are well suited to use in cases where very soft clays or loose
sands and gravels are present in the soil profile or when piles are
being installed below the water table - conditions which can pose
problems for cast in-situ systems.
• Steel piles have a very high load-carrying capacity which can be
further enhanced, given suitable ground conditions, by the use of
high yield strength steel. The option of using a higher grade steel is
also useful when hard-driving conditions are anticipated.
• Because they are comparatively light in weight, but very robust,
they require no special handling equipment for transport and they
can be supplied in long lengths (up to 33m for some sections).
• The ease with which steel piles can be extended, increasing their
load carrying capacity, is of great value to the designer working with
a material as variable as soil. The inherent uncertainty of a
calculated pile capacity is less of a problem to the designer and the
effect of unforeseen ground conditions on the construction process
can be reduced. For example, to maintain load capacity if weak
soils are encountered, it is a simple welding operation to extend the
pile or where a pile achieves the required ‘set’ earlier than predicted
it can be shortened, with the advantage that off-cuts from piles on
one part of the site can be used as extension pieces for other piles.
• Steel bearing piles are extractable at the end of the life of the
structure and therefore the opportunity for either re-use or recycling
exists, resulting in an economic and environmental bonus. The
resulting site is enhanced in value since there are no old
foundations that can obstruct or hinder future development.
• Steel bearing piles are of the low-displacement type and therefore
there is no spoil to dispose of, which is of particular benefit when
piles are being installed into contaminated ground.
• Steel bearing piles can be readily used as raking members in order
to accommodate horizontal loads on structures such as bridge
abutments.
This chapter is designed to give an overview of bearing piles and
axially loaded sheet piles. Deep foundations using driven steel piles is
a subject in its own right. The ArcelorMittal document ‘Deep
Foundations on HP piles’ and the SCI publication ‘Steel Bearing Piles
Guide’ provide in-depth guidance on the subject.
Chapter 10/1
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
Section
Mass
Dimensions
h
kg/m mm
b
tw
tf
Steel
area
A
mm
mm
mm
cm2
Total
PeriMoment
area meter of inertia
A tot
P
Axis Axis
=hxb
Y
Z
cm2
m
cm4
cm4
Section
modulus
Axis Axis
Y
Z
cm3
cm3
HP 200 x 43
42.5
200
205
9
9
54.14
410
1.180
3888
1294
388.8
126.2
HP 200 x 53
53.5
204
207
11.3
11.3
68.4
422.3
1.200
4977
1673
488
161.7
HP 220 x 57 )
57.2
210
224.5
11
11
72.9
471.5
1.265
5729
2079
545.6
185.2
HP 260 x 75 3)
75
249
265
12
12
95.5
659.9
1.493
10650
3733
855.1
281.7
HP 260 x 87 1) 3)
87.3
253
267
14
14
675.5
1.505
12590
4455
994.9
HP 305 x 79 3)
78.4
299.3
306.4
11
11
917.1
1.780
16331
5278
1091
344.5
HP 305 x 88 1) 3)
88
301.7
307.2
12.3
12.3
112
926.8
1.782
18420
5984
1221
388.9
HP 305 x 95 1) 3)
94.9
303.7
308.7
13.3
13.3
121
936.6
1.788
20040
6529
1320
423
3
111
99.9
HISTAR 4)
Table 10.2 HP piles - characteristics
333.7
HP 305 x 110 1) 2)
110
307.9
310.7
15.3
15.4
140
955.4
1.800
23560
7709
1531
496.2
Hi
HP 305 x 126 1) 2)
126
312.3
312.9
17.5
17.6
161
976.2
1.813
27410
9002
1755
575.4
Hi
HP 305 x 149 1)
149
318.5
316
20.6
20.7
190
1005
1.832
33070 10910
2076
690.5
Hi
HP 305 x 180
180
326.7
319.7
24.8
24.8
229
1044
1.857
40970 13550
2508
847.4
Hi
HP 305 x 186 1)
186
328.3
320.9
25.5
25.6
237
1052
1.861
42610 14140
2596
HP 305 x 223 1)
223
337.9
325.7
30.3
30.4
284
1100
1.891
52700 17580
3119
HP 320 x 88 3)
Hi
Hi
303
304
12
12
113
921.1
1.752
18740
5634
1237
370.6
HP 320 x 103
103
307
306
14
14
131
939.4
1.764
22050
6704
1437
438.2
Hi
HP 320 x 117
117
311
308
16
16
150
957.9
1.776
25480
7815
1638
507.5
Hi
HP 320 x 147
147
319
312
20
20
187
995.3
1.800
32670 10160
2048
651.3
Hi
HP 320 x 184
184
329
317
25
25
235
1043
1.830
42340 13330
2574
841.2
Hi
340
367
10
10
107
1248
2.102
23210
1365
449.2
HP 360 x 84 3)
88.5
881.5
1079
84.3
8243
HP 360 x 109 1) 2) 3) 109
346.4
371
12.8
12.9
139
1283
2.123
30630 10990
1769
592.3
HP 360 x 133 1) 2)
133
352
373.8
15.6
15.7
169
1314
2.140
37980 13680
2158
731.9
Hi
HP 360 x 152 1) 2)
152
356.4
376
17.8
17.9
194
1338
2.153
43970 15880
2468
844.5
Hi
HP 360 x 174 1) 2)
174
361.5
378.5
20.3
20.4
222
1367
2.169
51010 18460
2823
975.6
HP 360 x 180
180
362.9
378.8
21.1
21.1
230
1375
2.173
53040 19140
2923
1011
Hi
Hi
HP 400 x 122 3)
122
348
390
14
14
156
1357
2.202
34770 13850
1998
710.3
HP 400 x 140
140
352
392
16
16
179
1380
2.214
40270 16080
2288
820.2
Hi
HP 400 x 158
158
356
394
18
18
201
1403
2.226
45940 18370
2581
932.4
Hi
HP 400 x 176
176
360
396
20
20
224
1426
2.238
51770 20720
2876
1047
Hi
HP 400 x 194
194
364
398
22
22
248
1449
2.250
57760 23150
3174
1163
Hi
HP 400 x 213
213
368
400
24
24
271
1472
2.262
63920 25640
3474
1282
Hi
HP 400 x 231
231
372
402
26
26
294
1495
2.274
70260 28200
3777
1403
Hi
) Section conforming to BS4: Part1: 1993.
) Sections also available according to ASTM A6-2000
) Sections are also available in steel grade S460
4
) Sections marked Hi are available in HISTAR 355 and HISTAR 460 grades
(see special HP catalogue for details).
1
2
3
Chapter 10/2
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
10.2 Types of load bearing piles
Four basic types of steel bearing piles are available:1 H Piles – columns and bearing pile sections
(see Table 10.2 for details)
2 Box Piles. These are formed by welding together two or more
units to form a single section and are sub-divided into the
following types:
1 CAZ Piles
2 CAU, CU, CPU-R, and CGU box piles
(see 1.16.2 for details)
3 Tubular Piles.
4 Sheet Piles. It should be noted that as well as being widely
specified for the construction of purely earth-retaining
structures, sheet piling also has a capacity to carry axial load in
addition to earth and water pressures and can be used to form
structures such as bridge abutments or basement walls without
modification. (see Chapter 1 for sizes)
Where piles are fully embedded, ie the whole length of the pile is
below ground level, an H-section pile is most suitable. This situation
usually occurs when piles are used to support land-sited structures
such as road and railway bridges and industrial buildings.
Box piles and tubular piles are most useful when part of the pile is
exposed above ground level, as in pier and jetty construction, or
when hard-driving conditions are anticipated. They can also be
incorporated into a plain sheet pile wall to increase its bending
strength and/or its ability to support axial loads. These sections
possess a comparatively uniform radius of gyration about each
axis, and hence provide excellent column properties, which is a
particular advantage in these situations.
10.3 Design
10.3.1 General
The basis of design for any bearing pile is its ultimate axial
capacity in the particular soil layers in which it is founded. This
can be determined by testing the pile after it has been installed or,
more usually by using empirical formula at the design stage to
predict the capacity from the soil properties determined during the
site investigation. From this it can be seen that a good site
investigation is of paramount importance to the design process.
The structural capacity of the pile itself must also be determined
to ensure that it is adequate to transmit the foundation loads from
the structure to be supported into the founding soil. Provided the
soil is not of a very soft consistency, steel bearing piles can
generally be considered as fully laterally restrained by the soil over
the length of embedment. This means that, in most cases, the
maximum structural capacity of the bearing pile can be used in
the calculations.
Chapter 10/3
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
10.3.2 Determination of effective length
The structural capacity must be checked when a pile projects
above the soil level for a jetty or mooring dolphin. In this case the
above ground section must be designed as a free-standing column.
The effective length of the column (L) for the determination of its
slenderness ratio is dependent on the type of ground at the
surface. Where soft soils are encountered ‘L’ should be taken as
the distance between the point of connection with the deck (or
bracing) and a point at half the depth of the soft strata or 3m below
ground, whichever is the lesser. Where firm soils occur immediately
below bed level, ‘L’ is the distance between the point of connection
with the deck (or bracing) and a point located at bed level.
Hence, if the top of the pile is fixed in position in the orientation
being considered but is not effectively fixed in direction, the
effective length is ‘L’. If however, the pile is also fixed in direction
the effective length should be taken as 0.75 x L.
For partial fixity in this situation the effective length should be taken
as 1.5 x L.
When the top of the pile is neither fixed in position nor in direction
in the orientation being examined, the effective length is 2 x L.
Very soft strata such as liquid mud should be treated as water for
design purposes.
10.3.3 Vertical Load Capacity
The ultimate load carrying capacity of a pile in the ground can be
assessed by calculation using a variety of different methods.
Possibly the most suitable for driven piles in general is that based
on CPT (Cone Penetration Test) results but it is less reliable in
compact gravels, marls and other hard soils.
The designer is aiming to use the available soil test data to
establish acceptable values for the skin friction and end bearing
resistances that can be generated.
The following method of analysis, based on SPT test results, has
been in use for many years
Granular soil (SPT Method from Meyerhof)
The ultimate capacity of a bearing pile in granular soil can be
determined from the SPT values obtained from site investigation
boreholes using the following formulae
Ultimate Capacity QUlt = Qs + Qb.
Ultimate Shaft Resistance Qs = 2NsAs (kN)
Ultimate Base Resistance Qb = 400NbAb (kN)
Where Ns is the average dynamic SPT resistance over the
embedded length of the pile (blows/300mm)
Chapter 10/4
As is the embedded area of the shaft of the pile in contact with
the soil (m2).
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
N b is the dynamic SPT resistance at the predicted base of the pile
which is calculated using the following equation
N b = 0.5(N1 +N2)
where
N1 is the smallest of the N values over two
effective diameters below toe level
and
N2 is the average N value over 10 effective diameters
below the pile toe.
Ab is the area of the base of the pile (m 2).
For submerged sands, the N value needs to be reduced ( N red )
using the following relationship
N red = 15 + 0.5 (N – 15) for values of N which exceed 15.
Cohesive Soils
The ultimate capacity of a bearing pile in cohesive soils is a
function of the undrained shear strength of the soil and its area in
contact with the pile.
Ultimate Capacity Q Ult = Q s + Q b
Ultimate Shaft Resistance Q s = α Su As (kN)
Ultimate Base Resistance Q b = 9 Su Ab (kN)
Where
α is the pile wall adhesion factor (or soil shear strength
modification factor) for each soil layer
S u is the average undrained shear strength of the layer being
considered.
Values used for α under static load will diminish with increasing
undrained cohesion but generally lie between 0.5 and 1.0. This is
shown in Fig 10.3.3.1.
When calculating the values for A s and A b the possibility that
‘plugging’ may occur must be considered. This is the situation
where the soil does not shear at the pile/soil interface but away
from the pile and a plug of soil forms at the base which is drawn
down with the pile as it is driven. The various conditions are
shown in Fig 10.3.3.2.
It is recommended that the shaft friction area (A s) is calculated
assuming that no plug forms but when assessing the end bearing
area (A b), full plugging is assumed but a reduction factor of 0.5 for
clay soils and 0.75 for sands is then introduced.
Chapter 10/5
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
Fig 10.3.3.1
API RP2A - 20th edition (1992)
α =fs/Su
1
0.1
0.1
10
1
Su /σ′vo
Fig 10.3.3.2 H pile end bearing and skin friction ares
End Bearing areas
No plug
Partial plug
Corresponding skin friction area
Chapter 10/6
Full plug
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
Pile capacity from end bearing
When rock or another suitably competent layer exists, steel piles
can transmit the loads from the structure to the foundation in end
bearing alone.
The table below gives the ultimate axial load capacity for the
common bearing pile sizes based on the yield stress applicable to
a given steel thickness.
The values are applicable to piles founded in:
1 Hard and medium rock or equivalent, strata such as extremely
dense or partially cemented sands or gravels.
2 Soft rocks, dense sands and gravels or extremely hard clays,
hardpan and similar soils.
In the second case, the piles will act in a combination of end
bearing and friction in the founding stratum and the required
penetration will be greater than that for the first case where
penetration is dependent on the hardness of the rock and on the
degree of weathering of its upper surface.
It should however be noted that traditional load capacity tables
were based on a working stress of 30% of the yield strength of
the steel to give a factor of safety of 2 on the load and some
additional capacity to prevent damage should the driving stresses
increase. When driving piles through relatively soft soils onto rock,
a working stress of 50% of the yield strength of the steel could be
adopted giving a factor of safety of 2 on the applied loading. The
tabulated values below need to be factored to give comparable
load capacities for the various pile sections.
The ability of the rock on which the pile is founded to withstand
the foundation loads must be determined by establishing the
compressive strength of the strata (MPa) from site investigation.
Chapter 10/7
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
Table 10.3.3a H piles ultimate load capacity
Serial size
Chapter 10/8
Mass
Section area
kg/m
cm2
Ultimate load capacity
Steel grade
S235
S275
S355
kN
kN
kN
HP200
43
54.1
1272
1489
HP200
53
68.4
1607
1881
2428
HP220
57.2
72.9
1712
2003
2586
HP260
75
95.5
2245
2627
3392
HP260
87.3
111
2609
3053
3941
HP305
79
99.9
2348
2747
3546
HP305
88
112
2632
3080
3976
1922
HP305
95
121
2844
3328
4296
HP305
110
140
3290
3850
4970
HP305
126
161
3623
4267
5555
HP305
149
190
4275
5035
6555
HP305
180
229
5153
6069
7901
HP305
186
237
5333
6281
8177
HP305
223
284
6390
7526
9798
HP320
88.5
113
2656
3108
4012
HP320
103
131
3079
3603
4651
HP320
117
150
3525
4125
5325
HP320
147
187
4208
4956
6452
HP320
184
235
5288
6228
8108
HP360
84.3
107
2515
2943
3799
HP360
109
139
3267
3823
4935
HP360
133
169
3972
4648
6000
HP360
152
194
4365
5141
6693
HP360
174
222
4995
5883
7659
HP360
180
230
5175
6095
7935
HP400
122
156
3666
4290
5538
HP400
140
179
4207
4923
6355
HP400
158
201
4523
5327
6935
HP400
176
224
5040
5936
7728
HP400
194
248
5580
6572
8556
HP400
213
271
6098
7182
9350
HP400
231
294
6615
7791
10143
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
The following table give examples of the compressive strength of
rocks found close to the Earth’s surface in which piles may be
founded.
Table 10.3.3b Compressive strength
Rock type
Hard
Leptite
Diabase
Basalt
Granite
Syenite
Quartz porphyry
Diorite, gabbro
Quartzite
Quartzitic phyllite
Weak
100
Metamorphic phyllite
Layered phyllite
Hornblende
Chalkstone
Marble
Dolerite
Oil shale
Mica shist
Sandstone
Lava
Compression strength MPa
200
300
400
Variation about mean
Cylinder sample H = D
Cylinder sample H = 2D
Cube test
10.3.4 Piles subjected to tensile forces
Bearing Piles manufactured in steel have the advantage of being
able to withstand high tensile loadings, which makes them ideal
for resisting uplift forces. This tensile capacity also makes them
extractable without the need for special and expensive
techniques.
Table 10.3.3a gives the ultimate tensile capacity for each pile
section.
The tensile resistance of the soil/pile interface is calculated from
the skin friction on the pile shaft only.
Testing of tension piles to establish the tension load is a relatively
simple process of applying a load using a hydraulic ram founded
on the ground.
Chapter 10/9
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
10.3.5 Lateral loads
Lateral loads on piles vary in their importance from the major load
in such structures as transmission towers or mooring dolphins to
the relatively insignificant loads on low rise buildings.
For further information refer to SCI document ‘Steel Bearing Piles
Guide, Chapter 5 Lateral Load resistance.’
10.3.6 Pile groups
Where piles are installed in groups to support a structure, the
performance of the group is dependant upon the layout of the
piles and may not equate to the sum of the theoretical
performance of individual piles in the group.
A general rule is that the centre to centre spacing of the pile
should not be less than 4 times the maximum lateral dimension of
the pile section. However a check of the settlement of the overall
group should be made.
See SCI document ‘ Steel Bearing Piles Guide chapter 6 Pile
group effect’.
10.3.7 Negative skin friction
This phenomenon can occur when piles are driven through soft
compressible soils which are subjected to an external load such
as a surcharge. Squashing a compressible layer will apply a
downward force to the pile through skin friction, which
counteracts the load bearing capacity of the layer in question.
If this phenomenon is likely to occur it should be included in the
design calculations. The load bearing capacity of the pile can be
reduced to take into account the negative skin friction or a slip
coating can be applied to the length of the pile in the soft zone to
prevent the negative load affecting the pile.
10.3.8 Set up
The properties of the soil immediately adjacent to a driven pile are
changed by the process of forcing the pile into the ground, giving
rise to a phenomenon called set up.
Set up is the time interval during which the soil recovers its
properties after the driving process has ceased. In other words
the load capacity of an individual pile will increase with time after
the pile has been driven. In granular soils this can be almost
immediate but in clays this can take days, or months for some
high plasticity clays.
In granular soils this change can be in the form of liquefaction
caused by a local increase in pore water pressure due to the
displacement by the pile. In clays it can be due to the remoulding
of the clay in association with changes in pore water pressures.
Chapter 10/10
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
The load capacity of the piles should be verified by testing and if
sufficient time for set up to occur is not available before the pile is
loaded then its effects should be taken into account in the design.
The important point to remember is that in clay soils the capacity
of the piles will tend to improve over time.
10.4 Testing the load capacity of steel bearing piles
There are four categories of tests that are commonly used to
determine the load capacity of steel bearing piles.
1 Maintained Load Test and 2 Constant Rate of penetration test
Both these tests use similar apparatus and in both cases the
test load is applied by hydraulic jack(s) with kentledge or
tension piles/soil anchors providing a reaction.
Modern Pile pressing systems provide this information as part
of the installation process. The amount of force required to
install the pile can be used to gauge the likely capacity of the
pile.
In the Maintained Load Test, the load is increased
incrementally, and is held at each level of loading until all
settlement has either ceased or does not exceed a specified
amount in a stated period of time. In the Constant Rate of
Penetration Test, the load is increased continuously at a rate
such that the settlement of the pile head occurs at a constant
rate. A rate of 0.75mm/min is suitable for friction piles in clay,
whilst for end-bearing piles in sand or gravel a penetration rate
of 1.5mm/min may be used. The amount of kentledge or
tension resistance should always be in excess of the estimated
pile resistance and if kentledge is used, its support system and
‘foundations’ should be carefully considered well in advance of
the test.
It is desirable to carry out test loading of steel bearing piles to
failure/ultimate load to determine whether the factor of safety
or penetration is approximately correct and this can generally
be done without affecting the subsequent load carrying
capacity of the pile.
The ultimate bearing capacity of the pile is commonly defined
as the load at which the total head settlement is 10% of the
pile width or the load at which the net residual head
settlement, after removal of all load, is equal to a specified
amount eg 8mm
Chapter 10/11
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
3 Dynamic Testing
The test pile is instrumented with strain transducers and
accelerometers and is struck with the piling hammer. The force
and velocity data are recorded and analysed. Using this data,
methods are available that give an on-site estimate of the pile
bearing capacity, although more rigorous and detailed analysis
of the recorded data can be performed using a computer
program such as the Case Pile Wave Analysis Program
(CAPWAP). Using the program, an engineer can determine the
pile bearing capacity, in terms of shaft resistance and toe
resistance and the distribution of resistance over the pile shaft.
A load-settlement curve is calculated and is similar in form to
traditional static load tests. It is advisable to correlate the
results of dynamic pile tests with those of at least one
maintained load test.
4 Pile Driving Formulae
This approach, eg the Hiley formula, relates the measured
permanent displacement of the pile at each blow of the
hammer to the dynamic capacity of the pile, from which the
static capacity can be obtained by the application of a factor of
safety, normally 2.0. It should be noted that a dynamic formula
should be applied only to piles founded in hard or soft rocks,
sands and gravels or extremely hard clays and that it is then
applicable only if a satisfactory re-drive check is obtained, ie
the immediate set per blow on re-driving the pile after an
interval of several hours should be either equal to, or less than,
the previous final set per blow.
10.5 Welding of steel piles
Two main types of weld are used in steel piling:
1 Primary welds, used to form tubular or box piles and fabricate
corners, junctions etc in sheet piles.
2 Splice Welds to connect an extra length to a pile, either before
or after an initial installation to increase the overall pile length.
Until relatively recently there has been no generally agreed
Standard or Code of Practice stipulating the weld quality level to
be used for this type of work which has resulted in specifications
being written to an excessively high standard. Over specification
leads to higher labour and welding consumable costs, increased
Non-Destructive Testing costs, high rectification costs and
consequent delays to the overall construction programme.
Chapter 10/12
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
10.6 Installation of bearing piles
Until recent times the installation of bearing piles was limited to
Impact and Vibro driving methods (see Installation Chapter). The
recent development of a hydraulic pile press for bearing applications
has meant that there is now a very low noise and vibration free
method for installing bearing piles in urban areas. Large capacity
bearing piles can be created using sheet piles and Omega sections
to form a circle involving 4 to 8 piles. Installation of a bearing pile
formed in this way is most easily achieved by leader rig. Driving may
therefore be by vibrodriver or pile press. The leader rig mounted pile
press system has a number of hydraulic rams which clamp to each
pile in the group. The piles are installed by pressing one pile while
reacting against the others in the group to advance the piles in a
series of increments (see Section 11.3.25 for more information).
10.7 Driving shoes
Where piles are end bearing onto rock and the rock surface is not
horizontal a rock shoe can be used to seat the pile on the rock.
Other types of shoe can be used to strengthen the tip of the pile to
allow the pile to break through debris, scree, boulders and
weathered rock surfaces without damage.
It is also possible to profile the end of the section prior to driving.
10.8 Axially loaded sheet piles
The use of sheet piles in this handbook has focused, up to now on
purely retaining structures. However, the ability of sheet piles to
carry vertical loads in addition to predominantly horizontal loads
from the retained soil has been known about since their
introduction at the start of the 20th century. Over that time, this
ability has been put to good use in maritime structures where quay
walls need to support cranes on the sheet piles in addition to the
surcharges imposed on the ground behind the wall.
This ability to carry these combined loads is particularly relevant to
land sited structures such as bridge abutments and basements
below multi-storey buildings.
Point loads from columns can be transferred into the sheet piles
by use of a suitably designed capping beam.
10.9 Steel sheet piling in bridge abutments.
Steel sheet piles can be used to form the abutments of bridges in
one of two ways.
1 By using a line of sheet piles as the bearing structure and
landing the bridge beams directly onto the sheet pile capping
beam. In this situation the length of the bridge deck is
minimised. In this instance, the term sheet piles includes
standard rolled sections, box piles and high modulus piles.
Chapter 10/13
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
2 By forming a box using driven sheet piles which have an
upstand equal to the required height of the abutment. The
upstand is filled with a suitable fill material onto which the
landing for the bridge beams is formed. This method not only
uses the bearing capacity of the sheet piles, but mobilises the
contained soil as a foundation support, distributing the load
over a much larger plan area, reducing the soil stresses and
hence settlement.
10.10 Integral bridge abutments
Steel piles, either in the form of sheet piles in an abutment wall or
as a group of bearing piles supporting a conventional abutment,
are of particular use in integral bridge abutments. The flexible
nature of steel allows the abutments to move in response to the
lateral loads which are transmitted to the abutment from the
bridge beams due to thermal expansion, but remain robust
enough to cope with the vertical loads and such lateral loads as
braking forces and impacts.
10.11 Steel sheet piles in basements
Sheet piles are useful for the construction of basement walls in
buildings on restricted redevelopment sites. The narrow profile of
the finished wall together with equipment that allows installation
right up to the site boundary means that the usable space in the
basement is maximised.
The foundation loads from the perimeter of the building frame can
be applied directly to the sheet piling. The point loads from the
building frame can be distributed to the entire sheet pile wall by
means of a capping beam and these loads are then shed to the
founding soil over the entire length of the basement perimeter. If a
Chapter 10/14
Piling Handbook, 8th edition (revised 2008)
Bearing piles and axially loaded sheet piles
steel frame is being used for the building the anchor bolts for the
columns can be cast into the R/C capping beam in readiness for
the frame erection. A major advantage from this form of
construction is the potential for saving time on site as, once
installed, the steel piles can be loaded immediately.
This method reduces construction time when compared to more
traditional ones. The installed piles, when painted, give an
appropriate finish for basement car parks and various cost
effective cladding systems are available for habitable basements.
For further details the SCI publish a design Guide ‘Steel Intensive
Basements’.
10.12 Load bearing sheet piles
As the sheet piles will be designed for ultimate conditions and will
use all the friction available in the resistance of horizontal forces,
axial loads in sheet piles will have to be carried by an additional
length of pile beneath that needed for horizontal stability.
In addition to ascertaining the length of pile needed to support
the applied loads using one of the empirical methods mentioned
earlier in this chapter, it will be necessary to check that the
combination of bending and axial loads does not overstress the
pile section. This structural check should be carried out using the
appropriate national standard.
Chapter 10/15
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Installation of
sheet piles
11
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Contents
Page
11.1
Introduction
1
11.2
Driving methods
1
11.3
Driving systems & types of hammer
11.4
The soil
19
11.5
Choice of sheet pile section for driving
23
11.6
Resistance to driving
28
11.7
Guiding the piles & controlling alignment
37
11.8
Handling, sorting & lifting piles on site
40
11.9
Pitching
43
11.10
Threading devices
43
11.11
Driving assistance
44
11.12
Blasting
46
11.13
Driving corrections
47
11.14
Special aspects of installation
50
11.15
Extracting
51
11.16
Installing combined HZ or high modulus walls
52
5
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.1 Introduction
This chapter provides an introduction to the modern methods of
installing sheet piling taking into account the equipment available for
safe working practice.
A knowledge of the characteristics of the steel and the section are
not enough to guarantee good results prior to installation and this
chapter briefly describes the practical information to be considered
to ensure proper product installation. It also indicates how pile
driveability can be predicted following a thorough evaluation of the
ground conditions.
This chapter also contains information on pile driving equipment
which is current at the time of writing and includes impact hammers,
vibratory pile drivers, hydraulic pressing and special systems. Brief
descriptions of driving methods, ancillary equipment and guideline
procedures to assist in the adoption of good practice when installing
sheet piles are also included.
Finally some common installation problems are illustrated and
special aspects of driving briefly outlined.
11.2 Driving methods
Whilst it is recognised that, in common with most civil engineering
11.2.1 General
projects, a measure of flexibility is desirable to meet site conditions,
every precaution must be taken to maintain the necessary standards
of safety whilst giving the required alignment and verticality of the
installed piles.
Therefore principal consideration must be given to access of plant
and labour and working positions for handling the piles and
threading the sheets together. The length of the piles and height
from which they can be pitched and driven safely and accurately is
also important
Whenever possible sheet piles should be driven in pairs. The first
sheet piles in a wall must be installed with great care and attention
to ensure verticality in both planes of the wall. Control of the sheet
pile installation must be maintained during both the pitching and
driving phases of the installation process.
There are two principal pile driving methods available to installers,
pitch and drive and panel driving. The features, advantages and
disadvantages of each method are described below.
11.2.2 Pitch and drive method
This method requires equipment to control the verticality of the pile
during installation so that piles can be pitched and driven one by
one. The pitching operation can be carried out close to ground level
meaning that operatives are potentially at less risk and downtime in
windy conditions can be reduced.
Piles can be installed to final level by this method (necessary when
using the Japanese presses with single piles) or left at a higher level
Chapter 11/1
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
to backdrive using panel driving techniques with other, generally
heavier, hammers to speed up production or drive accurately in
deeper more difficult strata.
This method is the simplest way of driving piles but is only really
suited to loose soils and short piles. For dense sands and stiff
cohesive soils or in the case of possible obstructions, pitch and
drive is not recommended.
In recent years, the method has become more favoured by installers
as purpose built equipment is now available to adequately control
the pile during installation. In the right conditions, productivity is
maximised.
Fig 11.2.2
Driving
Direction
It is more difficult to control forward lean using the pitch and drive
method because the leading lock has less resistance than the
trailing or connected lock as a result of soil and interlock friction.
Although the piling may commence from a true vertical position,
the top of the piles will have a natural tendency to lean in the
direction of driving. This will get progressively worse if not
countered. When driving long straight sections of wall with a
planned pitch & drive method it may be advisable, with the
Engineers consent, to allow for supplying pre-fabricated tapered
correction piles for use at approximately fifty metre intervals. This
Chapter 11/2
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
is important to consider when using the Japanese pressing
machines because it may not be possible to revert to a panel
backdriving system to avoid or correct the forward lean problem.
With pitch and drive, the free leading interlock is constantly in
danger of rotation in plan which increases the deeper the free end
penetrates the ground as it is unsupported during the driving
operation. When a pile rotates during installation, friction develops
in the connected locks making driving progressively more difficult.
11.2.3 Panel driving
Piles may be threaded together above the ground in a support
frame to form a panel prior to driving. In this situation, both
interlocks are engaged before any driving takes place and this
balancing of the friction forces ensures maximum control and
accuracy. The piles are then driven in stages and in sequence into
the ground. Sequential driving enables verticality to be
maintained.
Sheet piles should be installed using the panel-driving technique
to ensure that good verticality and alignment is achieved and to
minimise the risk of driving difficulties or declutching problems.
This technique is important for maintaining accuracy when driving
long piles or driving into difficult ground
As a whole panel of piles has been pitched there is no need to
drive all piles fully to maintain progress of the piling operations.
During driving, the tops of adjacent piles can be kept close
together meaning that the stiffness of the piles is maintained
across both connected locks allowing the pile toe to be driven
through soil of greater resistance without undue deviation.
If obstructions are encountered, individual piles can be left high
without fear of disruption to the overall efficiency of the
installation process. Engineering decisions can then be taken to
attempt to remove the obstruction or drive piles carefully either
side of the obstruction before trying once more to drive or punch
through it if further penetration is necessary.
Panel driving is the best method for driving sheet piles in difficult
ground or for penetrating rock - which is unlikely to be possible
with the pitch and drive method. Piles are usually paired up or
neighbouring sheets levelled up at the head before commencing
the hard driving operation with a heavier hammer. Care should be
taken when piles are firstly pitched and installed in singles and
driven in the first stage with a vibrohammer. It is easier to execute
two stage driving in pairs if the piles are pre-ordered and installed
in crimped pairs. Difficulty of pairing up in the panel is avoided in
this way and safer more efficient operation of impact hammers
can be ensured.
Chapter 11/3
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Fig 11.2.3
1. Pitch, align and
plumb 1st pair.
3. Ensure last pair are
accurately positioned
& plumbed, drive last
pair.
5. 1st panel part driven.
7. 1st panel driven to final
level in stages. Last pair
of 2nd panel plumbed &
driven accurately.
The lower frame is usually left in position after removal of the upper
frame until driving is sufficiently progressed for it to be removed.
Chapter 11/4
2. Drive 1st pair carefully
& accurately pitch rest
of panel.
4. Drive remainder of
panel - working back
towards 1st pair.
6. 2nd panel pitched.
Last pair of 1st panel
become 1st pair of 2nd
panel. Gates supported
by through bolting to
last driven pair.
8. 1st panel completed.
2nd panel part driven.
3rd panel pitched.
Last pair of 2nd panel
becomes 1st pair of 3rd
panel.
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.2.4 Staggered driving
It is essential that the heads of adjacent piles or pairs are kept
close together to maximise the pile performance when driving in
hard conditions. This means that the installer should keep moving
the hammer from one pile to another in sequence to advance the
toe of the piling with less risk of damage or refusal. This technique
is known as staggered driving. It is not recommended that piles
are advanced more than 2 metres beyond neighbouring piles
unless driving conditions are relatively easy for the pile section
and equipment used.
11.2.5 Cofferdam and closure installation techniques
When installing cofferdams or high modulus walls, accuracy is
essential – particularly where it is necessary to pitch a pile of
significant length into both adjacent pile interlocks to close a gap.
If the gap tapers it will be very difficult to interlock and drive the
closure pile successfully. Therefore the panel driving method is the
favoured method for installing structures of this type.
CIRIA SP95 gives sound guidance on what needs to be
considered when installing sheet piles for cofferdams and dealing
with the issues that need to be addressed to be able to carry out
other operations in the dry. With any sheet pile project, the risk of
declutching should be minimised especially when men are
required to work in dewatered cofferdams.
When joining walls or closing to fixed positions, panel installation
methods are obligatory to maintain safe working conditions. It is
necessary to avoid the risks and potential disaster caused by declutched or damaged piles when planning, designing and
executing the works.
The panel driving technique is also best for the control of wall
length and creep by using appropriate guide walings. This may be
important when dimensions are critical. Curved walls can also be
set out using this method with curved walings to suit.
11.3 Driving systems and types of hammer
The choice of a suitable driving system is of fundamental
importance to ensure successful pile installation with due regard
to the safety of operatives and environmental disturbance.
The three basic driving methods are:
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Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Impact driving
This is the best method for driving piles into difficult ground or
final driving of piles to level in panel form. With a correctly
selected and sized hammer it is the most effective way of
completing deep penetration into hard soils in most conditions.
The downside is that it can be noisy and not suitable for sensitive
or restricted sites
Vibrodriving
This is usually the fastest and most economical method of pile
installation but usually needs loose or cohesionless soil conditions
for best results. Vibration and noise occurs but this can be kept to
a minimum provided the right equipment is used and the site is
not too sensitive
Pressing
Otherwise known as silent vibrationless hydraulic jacking.
Machines of various types are now widely used. This method is
very effective in clay soils but less so in dense cohesionless
ground unless pre-augering or jetting techniques are used.
This is the most effective method to use when installing sheet
piles in sensitive locations where piling would have not been
considered in the past.
11.3.1 Mixed driving methods
Specialist plant and equipment is now available that may combine
methods such as pressing and vibrodriving by use of a telescopic
leader rig fitted with a high frequency vibrodriver. The pressing,
which in this case is carried out by lowering the mast of the rig
using hydraulic rams, is known as ‘crowding’ and is normally
limited to a force of 15 to 30 tonnes
11.3.2 Impact hammers
There are several types of impact hammer available to suit the
particular requirements of a site. Most impact hammers will
involve a piston or ram and an anvil block with a driving cap
which spreads the blow to the pile head. The machines are
usually supported by a heavy frame or chassis and normally need
leg guides set up to fit snugly to the pile section being driven to
maintain a vertical position during operation. Alternatively the
hammers can be set up to be supported and aligned by a leader
rig. It is very important that, because of the height and
slenderness of these types of hammer, the hammer is prevented
from rocking or swaying when delivering powerful blows to the
piles.
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Installation of sheet piles
The principle differences between hammers are the size and
mechanism for delivering the blow from the ram. Some hammers
deliver the blow freely under gravity, others are able to accelerate
the fall of the ram and are described as double acting. In all cases
the effectiveness of driving will depend on the power and
efficiency of the blow.
Modern hammers are in widespread supply and, provided they
are adequately maintained, can be expected to totally outperform
the older types of pile hammer. Therefore the impact hammer
types described below are those that are most commonly in use.
Descriptions and detail of older types such as diesel hammers
can be found in previously published installation guides. Hydraulic
hammers totally outperform diesel hammers in terms of efficiency,
are more environmentally acceptable, and are less likely to
damage the head of the pile when transmitting the driving force.
11.3.3 Transmitting the blow to the pile
Any pile section can be set up to be driven with a suitable impact
hammer. However it is not only important to size the hammer
correctly but it is imperative that the driving cap and / or anvil plate
fits well and is correctly sized to suit the pile section being driven especially on wide piles or pairs of piles. The hammers should not
be used to drive piles of different widths without changing the
fittings. The central axis of the ram should always align with the
centre of the driven pile section in plan and the blow spread evenly
over the full cross sectional area of the pile.
11.3.4 Refusal criteria – hard driving
It is crucial to set refusal criteria for hard driving with impact
hammers. A penetration of 25 mm per 10 blows should be
considered as the limit for the use of all impact hammers in
accordance with the hammer manufacturer's recommendations.
Under certain circumstances a penetration of 1 mm per blow
could be allowed for a few minutes. Longer periods of time at this
blow rate will cause damage to the hammer and ancillary
equipment and may also result in damage to the pile head.
11.3.5 Hydraulic single acting hammers
These hammers are suitable for driving pairs of Z or U-piles in all
ground conditions. They are usually too wide to fit on single piles.
As the hammers can be adapted with heavy block ram weights they
are particularly suitable for prolonged driving into thick clay strata.
This type of hammer consists of a segmental ram guided by two
external supports; the ram is lifted by hydraulic pressure to a preChapter 11/7
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
set height and allowed to free-fall onto the anvil or driving cap.
The weight and the height of drop of the ram can be varied to suit
the pile section and the site conditions
Ram weights are usually set up in 3, 5, 7 or 9 tonne modes
although some up to 14 tonnes are available to suit driving of HZ,
high modulus and box pile sections. The drop height is variable
up to approximately 1.2 metres. At maximum ram weight and
stroke height a blow rate of 40 blows/minute can be achieved
when used in automatic sequence.
For driving in stiff clays it is always preferable to use a heavy ram,
with short stroke to minimise pile head damage and noise
emission levels.
The hammer controls are precise, and used correctly this type of
hammer can achieve 75-90% of rated output energy.
11.3.6 Hydraulic double-acting hammers
These hammers can be used on single or pairs of piles. They are
particularly suited to drive U-piles or heavy Z piles with reinforced
shoulders in hard driving situations and with rapid blow action can
be used effectively to penetrate very dense sands gravels and rock
This type of hammer consists of an enclosed ram which is lifted
by hydraulic pressure. On the downward stroke, additional energy
is delivered to the ram, producing acceleration above that from
gravity alone and powerful blows to strike the anvil or driving cap
which is purpose built to fit the pile section.
When set up for use with sheet piles, these hammers
will deliver a maximum energy/blow of 15 kNm to
90kNm with a blow rate up to 150 per minute. The
electronic control system ensures optimum control of
the piling process.
The ram weight of the machines suitable for standard
sheet pile sections range from 1.2t to 6.5t
Bigger machines are available for driving large nonstandard pile sections and HZ piles for high modulus
systems and offshore projects. The total weight of the
hammer ranges from approximately 2.5t to 20t.
The machines are usually rope suspended from a crane
and because even the lighter machines are very
powerful, effective driving systems are available at
significant reach using large crawler cranes.
Under normal site conditions it is usual to select a ram
weight that is in the range 0.75 to 2 times the weight of
the pile plus the driving cap.
Chapter 11/8
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.3.7 Control and settings
These hammers can usually be operated on different settings to
suit the pile and ground conditions. For instance a heavy ram
weight ratio hammer on wide piles can be used with a low setting
to suit driving in clay and smaller hammers on a rapid blow setting
can be used to drive single piles in dense sandy soils. Equipment
to provide digital readout of energy and blow count, for driving
records and control, is available to be fitted to most machines.
11.3.8 Impact hammers and driving stresses
The driving stresses in the pile, when using impact hammers, are
likely to be greatest at the head of the pile. This is known as the
peak head stress value (σp). The mean driving stress (σm) is
estimated by dividing the driving resistance (soil resistance +
friction) by the cross-sectional area of the pile.
The peak driving stress can be estimated using the following
formula:-
σ p = σm . [ (
) -1 ]
where ξ represents the efficiency of the blow from the piling
hammer (e.g. 1 = 100% efficiency, 0.75 = 75% efficiency, etc).
Where the impact hammer has a low efficiency (for instance, diesel
hammers may rate at 30%-40% efficiency) then the yield stress of
the steel section may be exceeded by the peak driving stress
causing buckling at the pile head.
Also note that for highly efficient hydraulic hammers which usually
operate at 85 to 95% efficiency, the hammer energy may be
transmitted effectively to the toe of the pile. It is therefore
important that the pile continues to penetrate the ground when
driving for a sustained period because toe damage can occur
when the penetration rate is low or refusal sets are exceeded.
11.3.9 Vibratory pile drivers
These hammers are usually the quickest and most effective
equipment for driving piles in loose to medium dense cohesionless
soils. They are particularly useful for extracting piles or withdrawing
the pile being driven in order to take corrective action.
11.3.10 Mechanism and use
Vibratory driving works by reducing the friction between the pile
and the soil. The vibrations imparted to the pile temporarily disturb
the surrounding soil causing minor liquefaction, which results in a
Chapter 11/9
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
noticeable decrease in resistance to movement of the pile through
the soil. This enables the pile to be driven into the ground with
very little added load, ie. its own weight plus the weight of the
driver or additional crowd force if the vibrodriver is used with a
leader rig.
For rope suspended operations, crawler cranes are usually used.
Telescopic mobile cranes are not recommended for use with
vibratory pile drivers.
The typical vibratory driver generates oscillations inside a
vibration case in which eccentric weights are gear-driven by one
or more motors. The weights turn at the same speed but in
opposite directions resulting in purely vertical oscillations as the
horizontal components of the forces cancel each other out.
Vibratory drivers can be powered by electric or hydraulic motors
- or a combination of both - , the input energy being provided by
a silenced power pack.
Hydraulically operated clamps mounted under the vibration case
ensure a secure attachment and transmit the oscillating
movements to the pile. The crane or leader rig suspending the
vibratory driver must be isolated from the vibration case by rubber
cushions or spring elements. The variable speed features of
hydraulic vibrators enable the frequency of the system to be
matched to varying soil conditions.
11.3.12 Use as an extractor
The vibratory pile driver is also a very efficient pile extractor if the
weights are rotated in the reverse direction. The extraction force
applied to the sheet pile will depend on the size of the vibrator
and the pulling force that can be applied to the pile from a safe
stable position. This force will be a function of the capacity of the
crane or rig and the distance it is located from the pile line.
Chapter 11/10
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.3.13 Types of vibratory hammer
Vibratory hammers are available in a wide range of sizes and also
operate in different frequency modes. The standard machines
usually operate at a frequency between 800 to 1800 RPM. The
power available is described by the centrifugal force of the
hammer which ranges from 400 to 1400 kN for telescopic rig
mounted units up to 5360 kN for fixed leader or rope suspended
models.
Higher frequency drivers are also available extending the range up
to 3000 RPM. The high vibrations developed attenuate very
rapidly limiting any problems to adjacent properties. The Variable
(Resonance free) High frequency machines allow the frequency
and power to be adjusted at start up and shut down to eliminate
resonance and the generation of unwanted vibrations through the
upper strata on sensitive sites and close to buildings.
11.3.14 Ground conditions and use of vibrodrivers
The soils best suited to vibration work are non-cohesive soils,
gravel or sand, especially when they are water-saturated and
provided the soil is not too dense. If SPT’s over 50 prevail then
driving will be difficult. Machines operating at higher amplitudes
are normally more effective in difficult soils. With mixed or
cohesive soils, vibro-drivers can also be very effective where there
is a high water content and the ground is loose or soft.
Clay soils have a damping effect and reduce the energy available
for driving the pile. Vibratory driving is difficult where firm or stiff
clay soils are encountered but once again a high amplitude is
likely to give the best results.
11.3.15 Gripping the pile
All pile sections can be driven with vibrohammers but attention
should be given to the area where the machine jaws grip the top
of the pile. For example, the thick part of the pan on U type piles
is most suited for this when driving or extracting piles singly. If the
jaws need to be attached to the web of a pile section – for
instance on Z-piles – care should be taken to avoid ripping the
steel especially during extraction. Tearing can be a particular
problem with wide piles if the vibrodriver is equipped with small
size grips and attaches to the pile at handling hole level. Multiple
clamps are available and it is recommended that they are used on
paired sections especially when driving wide piles. A correctly
fitting clamp should have grips in good condition – particularly
when it is being used for extraction - and recesses to
accommodate the pile interlock if used in the centre of paired
units.
Chapter 11/11
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.3.16 Refusal criteria, limitations and hard driving
Formulae to determine the size of vibratory driver needed for a
given set of conditions vary from manufacturer to manufacturer
and readers should obtain guidance from their plant hire company
on this topic if in doubt. Vibrators are also used for installing
bearing piles and high modulus or HZ king piles. Note that
performance on sheet piles and isolated piles is different and care
should be taken not to undersize the hammer or overdrive the
pile.
It is essential that movement is maintained when driving or
extracting piles with vibratory hammers and it is generally
recognised that a penetration rate of approximately 50 cm per
minute be used as a limit. This not only acts as a control on
possible vibration nuisance but also as a precaution against the
detrimental effects of overdriving.
When refusal occurs and the pile ceases to move, the energy
being input by the vibrodriver will be converted into heat through
friction in the interlocks of the pile being driven. The steel can
sometimes melt and damage the interlocks themselves, any
sealants being used and also the hammer if prolonged driving in
refusal conditions takes place.
Performance may be improved by using water jetting (see 11.11)
and/or by adding extra weights to the vibrohammer.
11.3.17 Setting up the hammer and driving methods
The driving method to be adopted needs to be taken into account
when choosing the type and model of hammer. Rope suspended
machines are best if heavy extraction or pitching in panels are
used. Small rope suspended vibrators are sometimes used as
starter hammers for long piles or when the hammer needs to
operate at distance from the crane.
Vibrohammers can also be mounted on tall masted leader rigs.
Double clamps can be used to centralise the driving action on
long paired piles and the equipment is specially suited for use
with pitch and drive methods.
Telescopic leader rigs (picture (a) below) generally use high
frequency vibrators and can apply a crowding force from the
telescopic pistons which adjust the height of the mast to deliver
additional driving or withdrawal force. These machines can
therefore press and vibrate the piles simultaneously. The length of
the mast, size of the rig and hammer will determine the capability
of the installation when using pitch and drive methods.
Chapter 11/12
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
(a)
(b)
11.3.18 Excavator mounted vibrodrivers
Excavator mounted, small, high frequency hammers (picture b
above) can also be used for installing very short piles. Care should
be taken when handling piles because excavators are not built for
this process and it is not as safe as using purpose built lifting
equipment when threading the piles together. This is an inferior
means of installing sheet piles and is less capable of driving piles
successfully and accurately. It should only be used when installing
short, light piles in loose soils when accuracy is not of paramount
importance.
11.3.19 Vibrationless sheet pile pressing
There are several forms that these machines can take but the
principle of operation remains the same. They represent a means
by which sheet piles can be installed without noise and vibration
often called pressing or silent, vibration free hydraulic jacking.
Pressing is the best system for avoiding noise and vibration
problems when driving sheet piles on sensitive sites. Especially
suited to the installation of piles next to buildings and party walls it
eliminates the need for expensive property surveys and minimises
the risk of disturbance.
Chapter 11/13
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
As the sheet piles can be installed permanently close to buildings
and boundaries more space is available for basements and
property development. This yields a major commercial benefit
which can be of more value than the cost of the wall itself.
11.3.20 The ‘Japanese’ Silent Pressing machine
The Japanese silent presses have been available now for over 15
years and are widely available across Europe. Many different
models (ie Giken, Tosa etc) have been developed providing
improved operational features which are suited to particular
installation situations. The machines and controls have been
developed to enable the plant to “walk” over the tops of the
driven piles. A system is available to work independently and
remotely from access roads and also over water.
The most readily available machines are used to drive single piles,
usually 600mm wide U-piles, although sometimes Z-piles may be
driven in singles in suitable conditions. Presses have been built
that can drive pairs of piles but it is important to note that
different machines are used to drive different pile sections so if
the pile sections to be driven are not 600mm wide U-piles then
the availability of an appropriate machine should be checked.
The machines, which are especially suited for use in cohesive
soils, are hydraulically operated and derive most of their reaction
force from the friction between the soil and previously driven
piles.
Chapter 11/14
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.3.21 Procedure and control
The most widely used machine is the Japanese silent press which
jacks one pile after another to full depth, using a pitch and drive
procedure, while walking on the previously set piles. These
machines work independently from a crane which is used to
handle the piles.
The sheet piles are fed by a crane into the enclosed chuck or
pressing jaws of the machine which acts as a guide to align the
piles without the need for guide walings. Setting out control is
executed by using a laser light beam focused on the leading
interlock of the pile being driven. The operator adjusts the
verticality and position of the leading lock by remote control and a
push pull action on the pile during driving.
The press is able to move itself forwards (‘walk’) automatically
using remote control. The machine raises its body and travels
forward to the next position without crane support.
11.3.22 Starting off
A reaction stand weighted down with kentledge or delivered sheet
piles is used to commence the pile line using a few temporary
piles to precede the first working pile to be driven. A crane is
used to initially lift the machine on to the reaction stand but there
is usually no need to lift it off again until completion of the pile
line. Ancillary equipment is also available that has been designed
to ‘walk’ along the top of the installed piles, including a crane, to
enable the whole piling operation to be carried out on the top of
the sheet piles without any other means of access.
11.3.23 Operational issues and suitability
These presses can also be used for withdrawing temporary sheet
piles using this silent, vibrationless method.
The machines work best in clayey, cohesive or very fine grained
soils and are usually supplied with jetting equipment for low to
high pressure water jetting. This is necessary to loosen fines in
cohesionless strata and is also used to lubricate dry soils to make
driving easier. For difficult or dense cohesionless strata or gravely
soils pre-augering is usually required to loosen the soil. Preaugering can also be used to probe for and deal with obstructions
prior to commencement of the piling. Superficial obstructions are
dealt with by digging a lead trench and either backfilling with
suitable material or using the trench to control surplus water and
arisings when jetting.
Chapter 11/15
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Japanese pressing machines are not capable of driving piles that
have already been installed by other means and therefore cannot
be used with panel driving techniques except for initial setting of
the panel.
11.3.24 Panel type silent pressing machines
These pressing machines can drive the sheet piles after they have
been installed in a panel but need to be set on the panel using a
crane or attached to a driving rig.
The Pilemaster has been in service for many years and uses panel
driving techniques. It has 8 rams (delivering up to 200t pressing
force per ram) which clamp to plates which, in turn, are bolted to
the heads of the piles to be driven. This can be a tedious
operation but good silent pressing results are obtainable in stiff
clay. Z-piles are preferred with this equipment because the plates
can be attached to the web of the piles on the ground before
pitching and preliminary driving with a vibro hammer. If U-piles are
used the plates would need to be fixed to the pile heads after the
vibro driving is completed.
The Pilemaster is still available and is used for hard pressing in
London clay and other heavy clay soils when jetting and pitch &
drive methods are unsuitable. It needs to be handled by a heavy
crane.
The Hydropress, shown below, is smaller than the Pilemaster but
can deliver up to 80t pressing force on 4 rams which clamp
directly to the pile pans.
This machine is usually mounted on a leader rig or heavy
excavator.
Chapter 11/16
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
It should be noted that panel type pressing machines are not
suitable for medium dense cohesionless strata and are not
compatible with water jetting equipment.
These machines are usually considered for driving in clayey soils
only or for completion of a drive into clay after the piles have been
driven firstly through cohesionless strata usually by high frequency
vibrators. It is therefore important to level the pile tops before
application of the panel press
The rams (hydraulic cylinders) are connected to the piles in such a
manner that both tensile and compressive forces can be applied.
Pressurising the rams in sequence while the others are locked
enables the piles to be pushed into the ground, one or two at a
time, to the full extent of the rams. The cycle is then repeated to
completion.
11.3.25 Silent pressing and high frequency (HF) vibrating combined –
the DCP power push
Recently developed, this innovative system combines the power
of the silent panel drive system with the versatility of the
telescopic leader rig. This machine can be set up to drive AZ, AU,
PU and PU-R piles in pairs but they must be supplied in
uncrimped form. The HF vibratory method may be combined with
the crowding force available from the rig to commence the driving
operation in order to develop sufficient reaction force for the press
to operate. In this way the commencement of the drive causes
very little noise and vibration before the heavy duty pressing
mechanism is used for the final stages of driving.
Chapter 11/17
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
The rig is capable of being used for both pitch and drive and
panel driving techniques. Rams or cylinders can be arranged in
multiples of paired units to deliver push-pull forces to the piles for
either driving or withdrawal. It can also be used to finish piles that
have been previously installed using other methods, particularly
for ground conditions such as sands or gravels overlying clays.
Each double acting cylinder can generate 200t pressing force.
Reaction is derived from the weight of the press, the crowd force
from the piling rig and by gripping adjacent piles to mobilise static
skin friction.
The cylinder and hydraulic jaws can be reconfigured to suit
different pile types and layouts including box piles formed from
sheet piles (see diagram below and 1.16.5). Up to 4 cylinders can
be used on a leader rig and 8 cylinders in line can be used when
crane mounted.
Drive sequence for a 4 pile box
5
4
3
2
1
Chapter 11/18
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.3.26 Silent pressing and augering combined – silent driving into rock
For soil conditions where water jetting and conventional augering
techniques would be ineffective, pile driving is now made possible
by use of the Super Crush Piling System. A development of the
Japanese silent pressing machine, this system uses an integral
rock auger inside a casing to penetrate hard ground. The
pressing-in action is carried out while simultaneously extracting
the auger. As for all situations where augering is involved, care has
to be taken not to remove the soil.
This technique enables silent piling into rock and allows sheet
piles to be designed to take significant vertical loads in end
bearing. Piles may also be extended by butt welding on site to
build deep sheet pile walls that otherwise would not be
considered feasible using traditional installation methods. (48m
long piles have been installed in Tokyo using this type of machine)
Consideration should be given to the integrity of the seating of the
pile and the effectiveness of the water cut-off provided when
using this technique. Injection grouting or re-seating of the pile
using vibratory or impact driving may be necessary to repair holes
or voids in the soil strata caused by the augering process.
The advantage of using these machines in city centres for deep
basement construction can be very commercially important for
sustainable solutions.
11.4 The Soil
11.4.1 Site conditions
For the successful driving of sheet piles, it is essential that a good
knowledge of the site conditions is available to enable an accurate
assessment to be made of environmental and geological
conditions.
The local environment of the site will influence working restrictions
such as noise and vibration. Each site will be subject to its own
unique set of restrictions which varies according to the proximity
and nature of neighbouring buildings, road category, underground
services, power supplies, material storage areas etc.
Chapter 11/19
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Geological conditions refer to the vertical characteristics of the
soil strata. In order to achieve the required penetration of the
sheet piles, site investigation of the soils together with field and
laboratory tests can aid installation assessment by providing
information on:
a) stratification of the subsoil
b) particle size, shape distribution & uniformity
c) inclusions
d) porosity and void ratio
e) density
f) level of the groundwater table
g) water permeability and moisture content of the soil
h) shear parameters, cohesion
i) dynamic and static penetrometer test results and results of
standard penetration or pressuremeter tests.
11.4.2 Soil characteristics
The following table shows the density in relation to penetrometer
and pressuremeter-test results for non-cohesive soils:
Table 11.4.2a
Standard
penetration
test - dynamic
SPT
N30
Cone
penetration
test - static
CPT
qs
MN/m2
Pressuremeter Test
pl
Density
EM
MN/m2
<4
2.5
< 0.2
1.5
very loose
4 to 10
2.5 to 7.5
0.2 to 0.5
1.5 to 5.0
loose
10 to 30
7.5 to 15
0.5 to 1.5
5.0 to 15
medium dense
30 to 50
15 to 25
1.5 to 2.5
15 to 25
dense
> 50
> 25
> 2.5
> 25
very dense
Chapter 11/20
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
The consistency of cohesive soils in relation to SPT, CPT and
pressuremeter-test results is as follows:
Table 11.4.2b
SPT #
CPT
N30
qs
MN/m2
Pressuremeter Test
pl
Consistency
<2
< 0.25
< 0.15
1.5
very soft
< 20
2 to 4
0.25 to 0.5
0.15 to 0.35
1.50 to 5.25
soft
soft to firm
20 to 40
40 to 50
4 to 8
0.5 to 1.0
0.35 to 0.55
5.25 to 8.25
firm
firm to stiff
50 to 75
75 to 100
EM
MN/m2
Undrained
shear strength
kN/m2
8 to 15
1.0 to 2.0
0.55 to 1.0
8.25 to 20
stiff
100 to 150
15 to 30
2.0 to 4.0
1.0 to 2.0
20 to 40
very stiff
150 to 200
> 30
> 4.0
> 2.0
> 40
hard
>200
The correlations between the different methods of soil tests are
not based on any standards.
Each method gives its own specific classification of the subsoil.
The tables serve only as an aid to the user to complement his or
her own experience.
# SPT values are not normally used for evaluating clay layers.
NOTE: 1 MN/m2 = 10 bar.
11.4.3 Driving system characteristics of various soils
Different types of soil present varying driving characteristics
dependant upon the driving system to be adopted. Brief notes on
each system are given below.
Impact driving
Easy driving may be anticipated in soft soils such as silts and
peats, in loosely deposited medium and coarse sands and gravels
provided the soil is free from cobbles, boulders or obstructions
Difficult driving may be expected in densely deposited fine,
medium and coarse sands and gravels, stiff and hard clays,
(depending on the thickness of the strata) and soft-to-medium
rock strata.
Chapter 11/21
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Vibratory driving
Round-grain sand and gravel and soft soils are especially suited
to vibratory driving. Easy driving should be expected when soils
are described as loose. Dense angular-grain material or cohesive
soils with firm consistency are much less suited. Difficult driving
may be experienced when dominant SPT values are greater than
50 or significant thicknesses of cohesive strata are encountered
It is also found that dry soils give greater penetration resistance
than those which are moist, submerged or fully saturated.
If the granular subsoil is compacted by prolonged vibrations, then
penetration resistance will increase sharply leading to refusal.
For difficult soil layers it may be necessary to pre-auger or loosen
the soil before installation. Jetting may also be necessary. For
penetrating rock, pre-blasting or use of specialised installation
equipment may be needed.
Pressing
This method is especially suited to soils comprising cohesive
and fine material. Easy driving is usually experienced in soft
clays and loose soils. This technique usually employs jetting
assistance to loosen silt and sand particles in cohesionless
strata to be able to advance the piles by pressing. Successful
installation will also depend on the soil providing cohesive
adhesion to the reaction piles.
Difficult soil conditions are found when dense sands and gravels
or soil containing cobbles or any large particles - which would
make jetting ineffective - are encountered. When boulders or rock
are encountered, reaction failure or refusal may occur. Lead
trenches may be of assistance for the removal of obstructions
encountered near the surface.
In these circumstances pre-augering is usually necessary to be
able to adopt the pressing technique; otherwise piles will have to
be driven to final level by percussive means.
Wet soil conditions are also favourable for pressing. In dry, stiff
clay strata, it is normal practice to use low pressure jetting to
lubricate the soil to pile interface and make driving easier.
Chapter 11/22
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.5 Choice of sheet pile section for driving
11.5.1 Influence of pile section properties.
Effective construction with sheet piling will depend on the
selection of an adequate pile section for the chosen method of
installation taking into account any environmental restrictions and
ground conditions over the full driven length of the pile. The pile
section selected must at least be able to accommodate the
structural requirements but this in itself may not prove to be
suitable for driving through the various strata to the required
penetration depth.
The driveability of a pile section is a function of its cross-section
properties, stiffness, length, steel grade, quality, preparation and
the method employed for installation. The piles also need to be
driven within acceptable tolerances to retain their driveability
characteristics.
The driving force required to achieve the necessary penetration is
affected by the soil properties and the resistance to driving that
develops on the pile profile. Resistance to driving will develop
through friction on the pile surfaces that are in contact with the soil
and as an end bearing resistance. Normally, the greater the
surface or cross section area of the piling profile, the greater the
driving force required but changes to the corner geometry of the
AU piles has resulted in a reduction in soil compaction and hence
resistance during driving. Friction in the interlocks will also
influence the driving force together with the physical nature of the
soil resisting movement at the toe of the pile. If the tip of the pile
meets an immovable object the pile will not drive.
11.5.2 Influence of driving resistance
Whatever force is required to drive the pile, it is necessary to
overcome the total resistance and move the pile without damaging
it. While the pile is moving, the hammer energy is expended in
overcoming the driving resistance but when the pile ceases to
move, the energy from the piling hammer will have to be absorbed
by the pile section. This situation increases the stress level in the
steel immediately under the hammer and at the point of maximum
resistance which will result in deformation of the pile, usually at the
head or toe - often both locations - when the driving stresses
exceed the yield stress in the steel. The driving stress will also
increase with inefficiency of the hammer blow or if the force is not
applied properly and spread uniformly across the whole of the pile
section being driven. Although it sounds illogical, it is also possible
to damage the pile head by using a hammer that is too light and
therefore unable to generate sufficient momentum to overcome the
resistances and drive the pile.
Chapter 11/23
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.5.3 Influence of steel grade and shape
There is a definite limit to the driveability of a given pile profile and
the steel grade being used. As the steel grade increases, the stress
that the piles can withstand also increases and so, logically, the
higher-yield steel piles are more resistant to head or toe deformation
than the same section in a lower steel grade.
In a similar manner, it can be seen that the larger the area of steel in
a profile, the higher the load it can carry and hence the heavier pile
sections will have increased driveability when compared to light,
thin sections. However, it must not be forgotten that under certain
driving conditions, a large cross section area may result in an end
bearing resistance that exceeds the increase in driveability.
Consideration of the soil layers and appropriate parameters will
enable the expected driving resistance to be assessed and hence a
suitable section to be selected.
11.5.4 Influence of method of installation
It is also very important to consider the installation technique to be
used. Pitch and drive (P&D) methods will reduce the driveability of
the section as discussed in section 11.6.8. When silent pressing
using Japanese hydraulic jacking machines, the stiffness of the pile
is of paramount importance to maximise driveability as the machine
operates on pure P&D methods.
Experience of driving sheet piles enabled relationships to be
developed to assess the driveability of particular profiles. One such
relationship used the section modulus of the pile profile as the key
factor. However, it is not possible to derive the most suitable choice
of pile section by consideration of section modulus alone. The
section required to be commercially effective and successfully
installed depends on consideration of a number of factors and the
following selection procedure is recommended:-
Chapter 11/24
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Figure 11.5.4 Summary diagram showing influences on choice of
section
Soil characteristics
- driveability
Thickness of strata
dominant SPT’s or
soil type
Structural design
requirements
Length of pile and
stiffness
Pile Section
Environmental
considerations
U-piles or Z piles
Suitable Technique
for driving
Singles or pairs
Minimum steel grade
Risk of pile damage
Hammer selection or
force necessary to
drive the pile
11.5.5 Influence of soil type
To assess the prevailing soil characteristics and driveability the
following tables may assist in the identification of suitable ranges
of sections for driving. The two distinct methods of installation,
panel driving or pitch & drive and three methods of driving are
taken into account. The choice of section and suitability of the
driving method will also depend on whether the piles are driven in
singles or pairs.
Please note that the following tables do not take into account
thicknesses of strata or the length of pile driven into the ground.
This will be considered in subsequent tables
Chapter 11/25
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Table 11.5.5.1 Driving in cohesionless or principally cohesionless
ground
Driving method
SPT value
Vibrodrive
Impact drive
Pressing in singles
(with Jetting)
0 -10
Very easy
Runaway problem
–use vibro method
to grip pile
Stability problem &
insufficient reaction
10 - 20
Easy
Easy
Suitable
21 - 30
Suitable
Suitable
Suitable
31 - 40
Suitable
Suitable
Consider pre-auger
41 - 50
Very difficult
Suitable –consider
high yield steel
Pre-auger
50+
Not recommended
Suitable –consider
high yield steel
Very difficult
The selection of a suitable pile section for driving into cohesive
strata is a complex process and the section choice is usually
based on previous experience. However it is possible to assess
the driving resistance using the surface area of the piling profile
and the characteristics of the cohesive strata. The following table
may be used for preliminary assessment.
Table 11.5.5.2 – Driving in cohesive strata
Driving method
Su value
Vibrodrive
Impact drive
Pressing in singles
0 - 15
Easy
Runaway problem
–use vibro method to
grip pile
Possible stability
problem &
insufficient reaction
16 - 25
Suitable
Easy
Easy
26 - 50
Suitable –
becoming less
effective with depth
Suitable
Easy
51 - 75
Very difficult
Suitable
Suitable
76 - 100
Not Recommended
Suitable
Suitable
100+
Not Recommended
Suitable
Difficult
Chapter 11/26
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Table 11.5.5.3 - Consideration of driveability characteristics relative
to cohesive strata thickness
Driveability of pairs
Su value
0-2m penetration
2-5m penetration
>5m penetration
0 - 15
Not recommended
Easy
Easy
16 - 25
Easy
Normal
Normal
26 - 50
Easy
Normal
Normal
51 - 75
Normal
Normal
Hard – consider
high yield steel
76 - 100
Normal
Hard – consider
high yield steel
Hard – consider
high yield steel
100+
Hard – consider
high yield steel
Hard – consider
high yield steel
Very hard – high
yield steel
Table 11.5.5.4 – Maximum recommended driving lengths for Silent
Japanese pressing rigs (Giken and Tosa type)
Section
Single PU 8R
Pressing force
(<60t)
Pressing force Pressing force
(60t-100t)
(>100t)
unsuitable
unsuitable
unsuitable
Single PU12
8m
6m
Not recommended
Single PU18 *
10m
9m
8m
Single PU22 *
13m
12m
11m
Single PU25
14m
13m
12m
Single PU32
16m
15m
14m
* Section with reinforced shoulders
11.5.6 Driving dynamics and driving characteristics for impact driving
sheet piles
Whichever method is adopted it is important that an acceptable
rate of penetration is maintained. The size as well as the type of
hammer must be suitable for the length and weight of the pile
being driven and it is assumed that the ground is penetrable.
For impact driving the rate of penetration, or blow count, is the
most recognisable indicator of the driving conditions. The mean
driving stress, σm, in the pile section will also be a function of the
resistance and section properties of the pile.
σm = Rapp / Aact
where Rapp is the total apparent resistance and Aact is the actual
cross section area of the pile being driven.
Chapter 11/27
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
The driving stress in the pile section can be used as an indication
of the expected driving difficulty; an approximate guide is given in
table 11.5.6.
Table 11.5.6
Driving condition
Driving stress
Rate of penetration
( blows per 25mm )
Easy
Normal
Hard
< 25% fy
25 – 50% fy
50 –75% fy
<2
2-8
>8
11.6 Resistance to driving
In penetrable ground, sheet piles are regarded as minimal
displacement piles. The driving resistance of a sheet pile (single or
pair) is simplified by the following relationship:
R app = Soil Resistance + Interlock Resistance
The apparent resistance depends on both the soil conditions and
the length of embedment. Unlike tubes, H piles and other
relatively closed sections, up to the onset of refusal, plugging of
sheet piles is unlikely and skin friction will dominate.
The frictional resistance will depend on the type of interlocks,
method of driving, whether the interlocks have lubricating sealants
or whether soil particles enter the locks and most important of all
the joint resistance will depend on the straightness and verticality
of the installation of adjacent piles relative to each other. Damage
to piles and poor condition will also increase resistance
significantly.
For a pile to drive effectively the total resistance has to be
overcome by such a margin that the pile progresses into the soil
at a high enough rate so that damage to the pile or the hammer is
unlikely to occur. In order to achieve this when impact driving, the
momentum of the hammer (namely the product of the ram mass
and the velocity at impact) must be sufficient. The delivered
kinetic or potential energy are often used as criteria for selecting
an appropriate size of impact hammer.
11.6.1 Impact hammer efficiency (ξ)
The delivered energy =
Hammer operating rated energy x efficiency of the blow.
(Please note that some hammers have adjustable output).
The efficiency takes into account losses of energy at impact, in
the pile driving cap and the effect of absorption into the pile.
Hammers of different types with different caps, plates and guides
have various efficiency ratings. The poorer the fit to the pile the
lower the efficiency of the hammer and hence the amount of
Chapter 11/28
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
energy delivered. The following table indicates the potential
difference in efficiency of hammers when used on sheet piling.
Efficiency of diesel hammers on sheet piling can also be affected
by a tendency to rock and move position during the driving
process resulting in inaccurate alignment of the central axis of the
hammer and the sheet pile section being driven.
Table 11.6.1
Impact Hammer type
Efficiency rating
(Hammers and fittings varying
condition conservative
expectation)
Efficiency rating
(Hammers and fittings in very
good condition)
Hydraulic
75-85%
85-95%
Diesel
20%-40%
30%-60%
The efficiency of the blow is also affected by absorption of energy
into the pile and the ratio of the impact hammer’s ram weight (W)
to the weight of the pile and driving cap (P).
Fig 11.6.1 demonstrates the effect on efficiency by comparing pile
to ram weight ratios on different types of hammer.
Fig 11.6.1
100
80
60
40
20
0
0.33
0.5
0.75
1
P/W ratio
1.5
2
3
Hydraulic hammer - pairs sheet piles
Hydraulic hammer - single sheet piles
Diesel hammer (good condition) - pairs sheet piles
Diesel hammer typical
Note that driving in pairs doubles the mass of the piles to be
driven. Larger hammers with heavier rams can be used on pairs
but it may not be possible to fit such a hammer on single piles.
Chapter 11/29
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Installation of sheet piles
11.6.2 Delivered energy
For impact hammers the delivered energy is either of the following:
a) For impact hammers where the ram weight delivers the blow
by free fall under gravity
E = Whξ where W = weight of the ram, h = drop height, ξ =
overall efficiency of the blow
b) For double acting or accelerated hammer
E = Eop ξ where Eop = Hammer operational delivered energy
set by the operator
The maximum deliverable energy
E max = ER ξ where ER = Hammer manufacturers maximum
energy rating
ER = 0.5 m v2 where m is the ram weight and v is the velocity
at impact
11.6.3 Measuring the delivered energy
a) By means of the hammer operation and control equipment:
For a drop hammer, the free fall distance is measured or set by
the operator – if the control equipment provides the facility, a
digital readout may be obtained for hydraulic drop hammers.
Diesel hammers are usually difficult to assess. Although different
settings are available on the controls, the usual method of
assessing the energy is by recording the blow rate and referring to
graphs provided by the hammer manufacturer.
For double acting hammers, timing the blow rate may also be
necessary but by far the best way is to have the controls
calibrated and fitted with digital readout equipment. Some
hammers can be controlled by pre-setting the required delivered
energy in this way. The readouts can also be connected to a
portable laptop to store and monitor the readout for driving record
purposes.
b) By means of dynamic monitoring:
Pile Driving Analyser (PDA) equipment is obtainable from
specialist firms and transducers can be fitted to the sheet piles so
that measurements can be taken for the following:Hammer efficiency, internal driving stresses and pile capacity.
The blow count and hammer stroke can be measured by using a
Saximeter or similar equipment
A software program for analysing measured force such as the
Case Pile Wave Analysis Program Continuous Model (CAPWAPC)
can be used to determine site specific soil parameters.
Chapter 11/30
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.6.4 Sizing the impact hammer
Studies have shown that modern hydraulic hammers which
operate at impact velocities in the order of 5m/sec are able to
overcome approximately 100 tonnes of apparent resistance per
tonne of ram mass at maximum performance. On the basis that
these hammers operate at 80 to 95% efficiency, it is possible to
relate the required delivered energy to the apparent driving
resistance at a rate of penetration approaching refusal as
illustrated in Fig 11.6.4. The line on this graph represents the
boundary between acceptable performance and effective refusal
(defined here as 10 blows per 25mm penetration); the chosen
hammer should operate on or below the line.
Fig 11.6.4 Relationship between required delivered energy and
apparent driving resistance near refusal
Total apparent resistance (T)
800
700
600
500
400
300
200
100
0
0
1000
2000
3000
4000
5000
6000
Required energy (kgm/blow)
7000
8000
9000
The total apparent resistance may be estimated on the following
basis:
Rapp = Rs x Fd where Rs is the sum of the skin friction resistance
over the embedded length of the driven pile.
The end bearing resistance is ignored for the purposes of sizing
the hammer, as the pile is assumed to be driven at a rate less
than 10 blows per inch and end bearing usually only becomes
significant as refusal is approached.
Skin friction = Area of pile in contact with the soil x unit frictional
resistance (See 10.3.3 for suggested method of assessing unit
friction resistances in cohesive and granular soils).
Fd is a dynamic resistance factor for sheet pile driving which
depends on the velocity at impact, damping effects and interlock
friction. Damping effects and interlock friction will also depend on
soil characteristics and length of embedment of the pile.
Chapter 11/31
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
The following table serves as an empirical guide to estimate Fd.
Table 11.6.4
Depth of pile embedment
Hammer ram velocity at impact
Less than 4m/sec
Hammer ram velocity at impact
More than 4m/sec
Up to 5m
1.2
1.2
5 to 15m
1.2 to 1.5
1.2 to 2.0
Over 15m
Not recommended
> 2.0
Using the above procedure a suitable pile hammer can be selected.
Please note that the selection of appropriate driving equipment is
an iterative process as the apparent driving resistance is a
function of the pile size and depth of embedment.
11.6.5 Driving dynamics and selection of suitable pile section and grade
of steel for impact driving
Taking into account the above tables, criteria for selection of the
pile section can now be established for impact driving in
penetrable ground.
When identifying a suitable pile section it is recommended that the
peak driving stress should generally not exceed 75% of the yield
stress.
Fig 11.6.5 Minimum steel area to be driven for a given apparent
driving resistance
S430GP
800
S390GP
S355GP
Apparent driving resistance (T)
S270GP
700
Note:
S460AP steel is
also available but
not shown here.
600
500
400
300
200
Stay to the right
of the lines to
keep stresses low.
100
0
25
75
125
175
225
275
325
375
Driven Steel area (cm2)
Figure 11.6.5 may be used to estimate the minimum area of steel
pile to be driven before selecting a pile section and steel grade.
To further reduce the risk of head damage, the area of steel
provided should be assessed on the basis of the area actually
covered by the hammer anvil not the cross section area of the pile.
Chapter 11/32
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
After selecting a section, the mean driving stress can be estimated
by dividing the apparent resistance by the section area.
Please note that for Rapp > 8000kN, high yield steel grades or
HZ/AZ systems may be appropriate. We recommend contacting
our Technical Advisory Service for further guidance when selecting
appropriate products and installation methods for anticipated
resistance of this magnitude or for hard driving where toe
resistance is significant for example when driving into rock.
11.6.6 Relationship between peak stress and hammer efficiency
For hammers with low efficiency it is possible that peak stresses
will be significantly higher than mean stresses.
Table 11.6.6 below is based on the equation
σ p = σm . [ (
) -1 ]
(introduced in Section 11.3.8) and shows the magnification factors
to be applied for different hammer efficiencies.
Table 11.6.6 Factor for peak stresses in the pile section
ξ
Factor
σp / σ m
0.9
0.8
0.7
0.6
0.5
0.4
0.3
1.108
1.236
1.390
1.582
1.828
2.16
2.65
The effect of reduced hammer efficiency can thus be taken into
account by multiplying the calculated apparent mean driving stress
by the factor from Table 11.6.6 to obtain the estimated peak
driving stress. If this is greater than 0.75fy then a larger section or
higher steel grade should be tried and the mean and peak stress
re-calculated.
11.6.7 General comments on driveability and use of tables
The method indicated above for the selection of pile section and
hammer does not take into account driving method.
Generally, a heavier section will drive better than a lighter section
and panel driving, provided the lead on the pile being driven is not
too great, will yield better results - in line with forecasts - than
pitch & drive techniques. In this respect there is a limit to the
suitability of any particular pile section in respect of a pure pitch &
drive technique.
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Installation of sheet piles
11.6.8 Influence of stiffness of pile and driving method
The pile length and its stiffness and the distance driven into the
ground ahead of its neighbour will principally govern driveability.
Panel driving methods should limit the distance any pile is driven
ahead of its neighbour. Recommendations are as follows.
Table 11.6.8
Easy
Normal
Hard
Driving into rock
Panel driving – by
impact driving in pairs
8m - At contractors risk
above this
4m
2m
0.5 m
Pitch & drive – by
vibro-driving methods
(refer to table 11.5.5.4
for pressing methods)
Singles possible
Maximum usually
about 14m -accuracy
difficult beyond this.
Pairs better than singles
- length of advancement
depends on section and
ability to control
alignment
Not to be recommended
Totally unsuitable
Methods of altering the
ground such as preaugering sometimes
possible
11.6.9 Sizing vibro-drivers
Although there is less risk of damage to the pile section where
conditions allow the use of vibrohammers, where driving becomes
more difficult the selection process for these hammers is different.
When using a vibrohammer it is imperative that the pile continues
to penetrate the soil at an appropriate rate. This will ensure that
the energy being input is expended in overcoming the soil
resistance and not in the generation of heat in the interlocks
which may be sufficiently high to weld interlocked sections
together.
Usually environmental considerations are a main concern but the
effectiveness of a vibrohammer in tough ground conditions is not
easy to predict. If pitch and drive techniques are used the
recommendations in the above table should be followed. If control
of alignment and good rates of penetration cannot be achieved
then panel driving techniques possibly using other types of
hammer should be considered. Generally vibrohammers with
greater power and self weight and higher amplitude will perform
better in harder and deeper strata. If it is necessary to complete
driving with a vibrohammer the following figure may assist in
identifying the size of machine required. Leader rigs may add an
additional crowding force of say up to 300kN but this may not be
sufficient to penetrate thick clay or dense soil strata. Also, it is
worth noting that for harder driving conditions associated with
trying to install long piles with up to 20m penetration using vibro
driving, the apparent resistance significantly increases and
hammers with much greater power are necessary unless impact
driving techniques are used.
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Installation of sheet piles
It is important to ensure that the vibrohammer is capable of
supplying the necessary centrifugal force to drive the piles and
that the power pack or carrier machine is capable of supplying
sufficient power for the vibrohammer to operate at its maximum
output.
Fig 11.6.9 Guidance for size of vibrohammer (rated by centrifugal
force) in terms of pile weight and driving conditions
3500
◆
3000
2500
◆
▲
2000
◆
▲
●
▲
◆
●
1500
▲
◆
■
●
▲
◆
▲
◆
●
●
●
■
1000
■
▲
▲
■
●
●
Vibro centrifugal force (kN)
◆
■
Easy
Normal
Hard
Very hard
■
■
■
■
500
●
▲
◆
0
0.5
1
1.5
2
2.5
3
3.5
4
Pile weight (tonnes)
Amplitude is also an important factor when sizing vibrodrivers.
Amplitude =
2000 x Eccentric Moment (kgm)
Dynamic weight (kg)
(where the dynamic weight includes the clamp and sheet pile)
Table 11.6.9 Minimum amplitude requirement
Easy driving
Normal driving
Hard driving
4mm
6mm
8mm
Note that the amplitude quoted in manufacturers literature does
not normally allow for the weight of the clamp and pile.
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Installation of sheet piles
11.6.10 Nomogram for checking minimum section size on the basis of pile
length and anticipated driving conditions
Step 1: Ascertain the driving conditions to be expected (ie. easy,
normal or hard)
Easy
Step 2: Check suitability of section against length taking into
account whether panel driving or P&D techniques are to be used.
Chapter 11/36
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Installation of sheet piles
11.6.11 Other factors affecting choice of section
After identifying a suitable pile section for driveability, the
following factors should also be taken into consideration to adjust
the final choice of section and steel grade.
Table 11.6.11 Other factors influencing choice of section
Factors
Condition or Technique
Influence on pile section choice
Increase steel grade
Possible reduction in section size when impact driving
Increase length of pile at head or toe
Increase pile section when using pressing or P&D method
Second hand piles, good condition
Increase section size or assume mild steel if grade unknown
Cobbly ground, boulders, rock etc
Increase section size and grade of steel, consider impact & panel drive
methods. May also consider reinforcing pile head and toe.
Pre-augering
Possible reduction in section size but reconsider structural
design implications and risk of increased deflections.
Allowing rotation at interlocks (P&D)
Increases friction - increase section size - not suitable for Z piles
Japanese standard pile pressing
Single U-piles best - increase pile section or stiffness
11.7 Guiding the piles and controlling alignment
11.7.1 General
It is recommended that a rigid guide waling system is employed
when driving steel sheet piles and purpose built steel pile driving
guides are available for this purpose. When using pitch and drive
methods it is often the case that the leader rig is assumed to
provide sufficient guidance to the piles and guide walings are not
used. While a string line will indicate the line that the piles should
follow, it can be easily moved and consequently will not prevent
misalignment. It is better to use guide walings to prevent rotation
of the interlocks and to limit the twist that can be induced in a pile
by the driving equipment - see also 11.7.4.
In the past, timber support systems were used but steel systems
are stronger and cheaper than timber and it is easier to make
temporary connections by tack welding steel guide walings to the
driven sheets and vice versa to control accuracy.
Walkways of the correct width, handrails and proper access
ladders must be provided to comply with H&S regulations.
Supporting trestles are quick to erect, strip and move, and can be
dismantled and neatly stacked for transportation. Safety features
are incorporated to provide safe access and working space when
assembly is either partially or fully complete. Walkway walings
provide safe access to the work area and a secure working space.
They are stiff box-girder beams and therefore will also serve as a
rigid guide and straight edge for accurate pile alignment.
Regular cleaning and the provision of drain holes is
recommended.
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Installation of sheet piles
11.7.2 Guide walings The functions of the guide walings are
1 To support piles in the vertical plane during pitching
operations;
2 To restrain the sheet piles during driving and prevent lateral
flexing;
3 To control parallelism of the pans or flanges of the piles;
4 To minimise rotation of the interlocks and thereby minimise
friction in the lock;
5 To act as setting out restraints and a physical check on the
correct alignment of the pile line;
6 To provide access for personnel to pitch the piles, carry out
welding and access the piles effectively, provided they are
wide enough to function as a walkway;
7 To facilitate fixing of permanent walings to structurally support
the sheet pile wall;
8 To act as a template when constructing walls with complex
and irregular shapes, setting out corner and junctions
accurately and construction of circular cofferdams.
It is particularly important that sheet piles are maintained in the
correct horizontal and vertical alignment during installation.
This is achieved by the use of effective temporary works and
guide frames which should provide support to the piles at two
levels. To be effective, the top and bottom guides must be rigid.
The temporary works may be pinned to the ground using
temporary H piles to prevent movement of the whole frame.
The effectiveness of the guides and accuracy of driving will be
improved by maximising the distance between the two support
levels. Very long sheet piles may need intermediate guides to
prevent flexing and other problems associated with the axial
loading of long, slender structural members. Pile installation may
exert large horizontal forces on the guides and it is essential that
the temporary works used to support the guide walings are
adequately designed and rigidly connected so that movement or
collapse does not occur during driving operations.
To prevent pile twist within the guide frame, the free flange of a Z
type sheet pile or free leg of a U type pile should be secured by a
guide block or strap connected across the waling beam during
driving.
When driving piles in water the lower frame can be attached
(above or below water) to temporary bearing piles.
When installing in marine conditions it is possible to use tube pile
sections as the horizontal walings to facilitate pitching if the lower
guide is expected to become submerged by the incoming tide.
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Installation of sheet piles
The curved upper surface of the tube will ensure that the pile being
pitched is guided into the correct location between the walings.
Ladder access must comply with H&S regulations and because of
the inherent danger, it is essential that sheet pile pitching is not
carried out from ladders. Access platforms must be positioned to
enable safe access throughout all operations.
Purpose built trestles and walkways are designed so that the top
guide waling can be removed at the appropriate time to allow the
pile to be driven with the bottom guide in place maintaining control
in the intermediate stages of driving.
11.7.3 Commencement of driving pitched panels with
rope-suspended hammers
It is recommended that two levels of guide walings are used. Rope
suspended hammers are usually used for the initial stages of panel
driving because they can be used at greatest reach with the crane
for withdrawing or lifting the pile if adjustments are necessary.
Alternatively, leader rigs may be used for initial driving if access is
available close to the pile line and the pile length does not exceed
the working height of the mast.
Temporary works provide support to the upper level guide waling
for the piles. To be effective it should be at least a third of the pile
length above the lower guide and preferably located as close to the
top of the pitched piles as possible.
11.7.4 Guiding the piles when installing with fixed or telescopic leaders
With this method it is usual for both the hammer and the pile to be
guided by the leader. As a result there is less need for upper guide
walings but it is nevertheless recommended that a rigid, ground
level guide waling is used to prevent excessive twisting of the
piles by the leader rig during the driving and correction process.
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Installation of sheet piles
It is important that the leader is always vertical and that the
hammer delivers its energy through the centroid of the pile profile.
Pile lines are found to be straight and true more often when
suitable guide walings have been used than when attempts have
been made to follow string lines between setting out pegs.
The spacing of the beams must be maintained by spacers to suit
the theoretical depth of the paired pile section + approximately
10mm. Therefore if PU22 piles are to be used the spacing of the
pile guide walings should be 450mm + 10mm = 460mm.
When pitching and driving a guide element consisting of spreader
and bracket should be located adjacent to the sheet piles being
driven to prevent frame bulging. The wider the guide walings are
set apart the more freedom for rotation occurs making the wall
untidy and more difficult to drive
11.8 Handling, sorting and lifting the piles on site
11.8.1 Stacking and handling
It is essential that the piles are stacked safely on firm level ground
before handling for installation. This is not only important to
prevent accidents caused by stacks toppling and trapping
personnel but also to minimise damage whilst piles are stockpiled
on site.
11.8.2 Bundles of piles
These should be lifted from the delivery lorry using a crane of
adequate size and lifting chains fitted by an experienced and
trained piling crew and banksmen. Bundles of piles can be heavy
so it is essential that adequate hard-standing is available for
unloading operations.
Unloading piles using telescopic leader rigs and excavators is not
recommended
Chapter 11/40
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Installation of sheet piles
11.8.3 Splitting bundles and lifting individual piles
These operations need special ancillary equipment which is
designed specifically for this purpose.
Makeshift equipment and use of inappropriate plant such as
excavators should be avoided.
Simple cast-steel shoes have been designed to slide between
each pile in a stack enabling them to be easily separated and
moved horizontally. The shoes are usually attached to long steel
rope slings which allow them to be attached at both ends of the
pile. U-piles are easy to handle in this way because single bars
balance well in the horizontal position. When handling pairs of
piles the shoes have to be attached to the same individual bar to
prevent the two piles from sliding apart. Spreader beams are
sometimes needed for handling very long piles and straight web
sections.
11.8.4 Shackles
A variety of special “quick” ground release shackles are available
and should be an essential part of the sheet pile installers
equipment.
These enable the crane connection to the pile top to be released,
when required, from ground level or walkway waling level. This is
fast, efficient and safe and eliminates the risk of personnel
climbing ladders to release the lifting device from a pitched pile.
The shackle uses a lifting hole in the head of the pile through
which a shear pin passes.
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Installation of sheet piles
Piles stacked in bundles should be carefully lifted with purpose
built shoes and suitable dunnage inserted to space out the piles
before connecting the quick release shackle (QRS). The slinging
holes in the piles should be ordered or cut to suit the QRS or
other lifting attachment to be used. It is necessary for personnel to
be trained to attach and check the QRS to ensure correct
insertion of the lifting pins in the pile head hole before the signal
to lift the pile is given.
11.8.5 Lifting chains
When telescopic leader rigs are used for pile installation the
process of lifting the pile off the ground is usually achieved by
attaching chains fastened near the end of the mast and driving
equipment. Holes of adequate size to accommodate the lifting
chains are usually cut in the webs of the sheet piles about 300mm
from the top of the piles before pitching. This enables the pile to
be lifted up to the hammer jaws near the top of the mast.
The pile is then driven and the chains are released near to ground
level before the hammer or mast needs to be moved away from
the pile.
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Installation of sheet piles
11.9 Pitching - connecting the interlocks when pitching the piles
Interlocking the piles together in the vertical position is called
pitching.
The greatest risk of injury to piling personnel occurs during pile
pitching so it is important to develop a safety plan and an
approved method of working before work commences.
The following actions or conditions must be ensured to comply with
H&S regulations
1 The lifting plant or crane must be securely connected to the
top of the pile until the pile is fully threaded and supported by
the ground. Piles should not be allowed to free fall.
2 Personnel threading the piles or handling the free end of the
pile being lifted must operate from a safe working platform or
ground level. Operatives must not stand on ladders or balance
on the tops of piles when piles are being pitched
3 Sufficient numbers of personnel need to be available for
handling the size of pile being pitched especially in windy
conditions. One or two operatives should restrain the pile from
swaying - using ropes if necessary. The crane operatives
should avoid slewing or moving the jib when operatives are
attempting to pitch the piles by hand. The piles should only be
lowered when the correct signal is given by a qualified banksman
As a consequence of panel driving, there is a need to interlock piles
and release the crane connection, at a high level, with efficiency and
safety. To do this correctly, appropriate temporary platforms need to
be erected and special threading equipment should be used.
11.10 Threading devices
The sheet pile threader is designed to interlock any steel sheet
pile accommodating the different profiles, handing and interlock
types without the need for a man to be employed at the pile top.
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Installation of sheet piles
The threader is attached
at platform level
The signal is given to
raise the pile
The spring mechanism
guides the interlocks in
place at the top
After the interlocks
engage the pile is
lowered and the
threader is removed
Use of a pile threader allows pile pitching to continue in windy
conditions which would stop manual interlocking, making the
work both safer and more efficient.
11.11 Driving Assistance
11.11.1 General
Under certain conditions, impact driving, vibrating and pressing of
piles can be made easier with the help of jetting. The process
delivers water to the toe of the pile where it loosens the soil causing
the toe resistance of the pile to reduce and, depending on the soil
conditions, causes a reduction of skin and interlock friction as it
flows back to the ground surface along the faces of the pile.
The equipment comprises a lance (and nozzle) fitted to the sheet
pile to deliver a water jet at the toe of the pile. The water is
delivered at controlled pressure by hoses connected to the lance
from a water jetting unit fed by a pump from tanks capable of
supplying sufficient water.
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Installation of sheet piles
The effectiveness of jetting is influenced by the density of the soil
and the proportion of fines present, the available water pressure
and the number of jetting pipes. Planning the disposal of water
and provisional of silt trap tanks is also necessary. Piling installed
in a leading trench will help to control the disposal of jetting water
and help to keep operations and the site as tidy as possible.
Care must be exercised to ensure that this form of ground
treatment does not endanger adjacent structures. It is not unusual
for a loss of fines to occur in the soil near to the pile but, other
than the risk of a small amount of settlement and a reduction of
the angle of friction of the soil acting on the wall, structural
properties of the sheet pile wall will be substantially unaffected.
Jetting equipment that can be controlled by the piling gang is
recommended. The least amount of water pressure should be
used to advance the piling and the piles should be finally driven to
level without jetting wherever possible to ensure that the integrity
of any cut-off at the bottom of the wall is not compromised and
that voids will not be created at the pile toe potentially reducing
the bearing capacity.
Test-driving to define the parameters is recommended.
11.11.2 Silent Pressing and Jetting
Silent pressing machines work best in cohesive soils. The
Japanese presses can be effective if cohesionless soils are
encountered because they can be used with water jetting
equipment. A water supply and disposal facility is therefore
required. Water jetting is not usually available for or compatible
with the panel jacking machines.
11.11.3 Low pressure jetting
Low pressure jetting is mainly used in cohesive soils with vibro
driving and in dry stiff cohesive soils with Japanese presses.
In combination with a vibratory pile driver, jetting can enable piles
to penetrate very dense soils.
In general the soil characteristics are only slightly modified,
although special care must be taken when piles have to carry
vertical loads. See ArcelorMittal publication, ‘Jetting-assisted
sheet pile driving’ for further details.
11.11.4 High pressure jetting
High pressure jetting may be used for driving in extremely dense
soil layers and if gravels are encountered when using Japanese
presses.
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Installation of sheet piles
If high pressure jetting is envisaged, water consumption should be
checked with the equipment supplier and provision made for
supply and disposal of the water with the Client and appropriate
authorities.
High pressure jetting should only be carried out with the
Engineers consent and an agreed method statement.
11.12 Blasting
This process is applicable to types of rock which until now would
have been classified as difficult or impossible for driving steel
piles to specific penetration designed requirements.
11.12.1 Normal blasting technique
Explosives are lowered into drilled holes and covered with soil
before detonation. This can create a V-shaped trench along the
proposed line of the wall or shatter the rock into various sized
particles. The size of the fragments in the trench is dependent
upon the amount of explosives used, the competence and
stratification of the rock and the spacing of the drilled holes. Preblasting may be more appropriate for stronger more brittle
competent rock types. Soft rock types are usually unsuitable for
blasting techniques.
Nevertheless if the blasting technique shatters the rock very well,
the driving conditions in the loosened area will still be very tough
and high yield steel and toe reinforcement of the piles is
recommended.
In many instances, the process has to be repeated locally,
because the blasting has failed to shatter the rock and the piles
refuse during the subsequent driving operation. As a result, this
process can be very costly, it is difficult to price and estimate
rates of production and each project considered using this
process is likely to be different
It is therefore recommended that sheet pile walls are designed
with maximum support towards the top of the piles to keep the
required penetration into rock to a minimum.
Chapter 11/46
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Installation of sheet piles
11.12.2 Pre-augering
Dense cohesionless strata are
usually pre-augered on the pile line
to loosen the soil before pressing is
attempted. Easier impact driving,
vibrating and pressing can be
achieved by pre-augering. Holes of
about 20cm - 30 cm diameter are
drilled at approximately 600mm
centres on the centre line of the wall.
Depths of up to 10m can easily be
treated using auger
equipment mounted on a
telescopic leader rig which may be
interchangeable with equipment for
installing the piles.
When loosening the soil by augering,
care must be taken not to remove the
soil and leave holes – as can occur when attempting to auger into
dense cohesionless soils underlying clay strata. Any holes that do
occur should be filled with granular soil before driving piles.
Pre-augering should be avoided in the passive zone, near the toe of
the piles and where artesian water could be encountered.
It must not be forgotten that augering effectively changes the nature
of the soil and possibly the water table regime in which the pile is
located which may invalidate the design assumptions. It is also likely
that wall deflections will increase especially in any temporary
construction stage cantilever condition.
11.13 Driving Corrections
11.13.1 Correction of lean
Care should be taken to pitch the first piles vertically and maintain
them in a true position within permitted tolerances.
In order to avoid the tendency of sheet piling to lean, the hammer
should be positioned over the centre of gravity of the piles being
driven and should be held vertically and firmly on the piles by
means of efficient grips. When driving in pairs the adjacent piles
should be square and true at the top and the hammer blow spread
evenly across the maximum area of steel by means of a correctly
sized and fitting anvil or driving cap.
Transverse leaning of sheet piles is eliminated by the use of efficient
guide walings. If the piles develop a transverse lean which needs to
be corrected, the piles should be extracted and re-driven in shorter
steps to maintain control.
Chapter 11/47
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Installation of sheet piles
Longitudinal leaning in the direction of driving may be caused by
friction between the previously driven pile and the pile being
driven or by incorrect use of the hammer and should be
counteracted immediately if it becomes apparent. If left
unchecked, the lean can become uncontrollable requiring piles to
be withdrawn until an acceptably vertical pile is found. Pile
installation can then continue using panel methods to reduce the
risk of further lean.
Prevention is better than the cure and when using pitch and drive
methods, driving should cease before the lean approaches the
maximum permitted verticality tolerance limits. Panel installation
methods should then be used to eliminate further leaning by
backdriving from piles installed with acceptable verticality towards
the leaning piles against the direction of installation.
In conjunction with the above method, longitudinal lean may be
corrected by pulling the misaligned piles back with a wire rope
while displacing the hammer from the centre of the pair towards
the last driven piles.
When a lean cannot be eliminated and piles cannot be withdrawn
and replaced, the error may be corrected by introducing taper
piles, but only with the consent of the Engineer.
11.13.2 Drawing down
When piles are driven in soft ground or loose sandy soils the pile
being driven may draw down the adjacent pile below its intended
final level. The problem sometimes occurs when the Pitch & Drive
method is used and is caused when more friction develops in the
interlock connected to the pile being driven than is available in the
interlock connected to the previously driven piles.
This may happen when either or all of the following occurs
- the piles are leaning forward
- the piles have been allowed to rotate causing interlock friction
- vibrodriving action has compacted sand into the interlocks
during installation
- interlocks have not been cleaned before driving
- interlocks have been damaged or bind together on one side of
the pile
A remedy for the problem when vibrodriving is to re-level the
heads by withdrawing the piles and tack welding them together in
pairs and proceeding with a panel backdriving method. Pairs of
piles will usually be driven easily in soft ground where this
problem is usually found.
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Installation of sheet piles
Alternatively impact driving may be used instead of vibrodriving.
Where the problem is encountered locally the simplest means of
prevention is to tack weld the pile being drawn down to the
temporary guide walings – however these must be adequately
supported so that they do not move or collapse when driving the
piles.
The problem is less likely to occur if the piles are installed with
good alignment and verticality and the problem may be alleviated
by introducing a sealant to the interlocks to prevent the ingress of
soil to the interlock area during driving.
11.13.3 Control of wall length
When using uncrimped piles, a limited degree of wall length
control may be achieved by adjusting the distance between guide
walings and rotation of the piles at the interlock positions to suit.
This is not recommended for permanent construction as rotation
at the interlocks will affect the appearance of the wall, can be
expected to increase driving resistance and will increase the
possibility of declutching. When piles are supplied crimped, this
method of wall length adjustment will not be possible as the
process fixes the position and orientation of the connected piles.
If accurate theoretical wall dimensions have to be achieved, it
may be necessary to introduce a fabricated pile.
11.13.4 Driving tolerances
Theoretical position and orientation of the sheet piles are usually
indicated in the driving plan on working drawings. Deviations from
this theoretical layout may occur due to rolling tolerances, soil
conditions and driving procedure.
General tolerances for a straight and plumb sheet pile wall should
be in accordance with the following figures (see also EN 12063).
a) deviation in plan normal to the wall line at the top of the pile
± 50 mm (± 75 mm for silent pressing)
b) finished level deviation from nominal level of top of pile
± 20 mm
c) deviation of verticality for panel driving all directions 1 in 100
d) deviation of verticality along line of piles for pitch & drive
1 in 75
Tolerances for plan and verticality are accumulative and designers
and architects should allow for this especially when considering
design of internal fittings or within a cofferdam.
Chapter 11/49
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Installation of sheet piles
11.14 Special Aspects of installation
11.14.1 Test-driving Where the driveability of the soil is difficult to assess, test-driving
is recommended.
Test-driving is undertaken to determine the pile section which,
when driven by a suitable hammer, will reach the required depth
most economically. Test drives should be carried out on the line of
the final wall, their number depending on the size of the project
and on the expected variations in the underlying strata. Good
control of the pile and the hammer is required and driving records
must be taken.
Subsequent extraction of the piles may give supplementary
information.
In the event that the piling is to carry axial load, it may be
convenient to use the test piles to carry out a load test using
Dynamic Analysis in conjunction with a suitable impact hammer.
Silent pressing machines may record pressing and withdrawal
forces which can assist Engineers to assess the ultimate skin
friction capacity of a pile for carrying vertical load.
Simple equipment for carrying out static load testing of the piles
is also available.
11.14.2 Driving in restricted headroom
Under bridges etc. the free height between soil level and the
structure is often insufficient to allow normal pile
threading/pitching. One possibility is to drive the piles in short
lengths, butt welded or fish- plated together as driving proceeds,
the joints being to the full strength of the section; but, if possible,
this should be avoided for reasons of economy. A better way of
overcoming the problem is to assemble a panel of piles
horizontally on the ground, the length of the piles being less than
the headroom. The panels should be bolted to temporary walings
and moved into position. In any case, the headroom may be
increased by the excavation of a trench along the proposed line of
the piling. Driving is commenced using a double-acting hammer
mounted in a cradle suspended at the side of the pile. As soon as
sufficient headroom is available, the hammer should be moved to
the normal driving position.
Chapter 11/50
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.15 Extracting
11.15.1 General
When piling is intended to serve only as temporary protection for
permanent construction work, it can be extracted for re-use by
means of suitable extractors which are usually of the vibratory or
jacking type.
For an evaluation of the required pulling force, the previous
establishment of a driving record for each pile is very useful. This
identifies the piles with the lowest resistance, thus defining the
most advantageous starting-point for the extraction work. If
driving records for the piles are not available, then the first pile to
be extracted should be selected with care. Piles near the centre of
a wall should be tried until one pile begins to move. If difficulty is
experienced, then a few driving blows may be used to loosen a
pile. It may also be necessary to reinforce the head of the piles to
aid the successful extraction of the initial pile. Accurate driving of
the piles in the soil makes extraction easier.
When designing temporary works and selecting the pile section it
may be necessary to increase the section to ensure good
driveability and minimise damage to the piles. The commercial
success of the operation will depend on the quantity of piles
recovered with minimal damage
11.15.2 Extraction by vibrator
Vibrators and extractors of various sizes are available. They
loosen the pile from its initial position, so that it moves with the
help of the pulling force of the crane. The limit values of the
extractors and crane loads given by the manufacturer must be
respected. The connection between pile and the extractor should
allow for the maximum pulling force of the crane and extractor.
11.15.3 Extraction by silent press
Silent presses are excellent for extracting piles in sensitive
locations, the extraction process being the reverse of driving.
Piles that have been pre-treated with sealants are ideal to extract
with the silent presser.
Chapter 11/51
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
11.15.4 Extraction using the sustainable base extractor
This powerful tool can be used to clear steel pile foundations from
a site and also extract long heavy sheet piles.
A maximum pulling force of approximately 400t is currently
available with this machine
It requires at least 1.5m working space either side of the pile line
and a firm hard-standing to work from. The machine needs to be
positioned at the open end of a pile line and work backwards. A
heavy crane is needed to move the extractor to different
positions.
11.16 Installing Combined HZ or high modulus walls
High Modulus walls may consist of special rolled King piles or
fabricated box piles combined with standard sheet piles. The King
or Primary piles are structural elements which are connected by
intermediate secondary sheet piles.
One of the most important and efficient systems that provides a
“straight” face suitable for Marine projects and deep berths is the
HZ system. The HZ beams are rolled specially up to lengths of
33m. These major sheet pile walls should only be installed by
leading experienced contractors equipped with heavy plant
suitable for offshore conditions where appropriate.
Chapter 11/52
Piling Handbook, 8th edition (revised 2008)
Installation of sheet piles
Techniques for successful installation involve panel driving
methods but involve installing the primary elements before
secondary elements in the panels. It is essential that the primary
elements are established accurately before joining together with
the shorter secondary piles. In this respect special temporary
works in the form of guide waling trusses have proven to be the
best method for setting out, supporting and commencing the
installation of the primary piles.
The procedure adopted to drive the piles is different to that of
installing standard sheet piling and different hammers need to be
used for the primary and secondary piles. Details of the
procedures and hints for suitable techniques are described in
more detail in the ArcelorMittal publication “HZ steel wall system
ref 1.4.01”.
The HZ system combines all hot rolled products mechanically
jointed together and is the best system available for joint integrity
when installed correctly.
Other systems may combine fabricated primary elements such as
tubes with interlocks welded on either side or box piles welded
together. In such cases all welding of interlocks and splicing
together to form the correct length needs to be executed in
accordance with relevant codes to high standards of
workmanship and testing.
In all cases the secondary elements must consist of at least two
suitable sheet piles (and no more than three) with interlocks
capable of withstanding additional stresses from the action of
forcing the sheets between stiff primary elements. Pairs of AZ
piles which have a Larssen type lock are considered the most
suitable for secondary piles in combined walls.
Declutching in dense fine sands may be avoided by filling the
interlocks with bituminous sealant prior to driving.
Chapter 11/53
1
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
12
8
Charts for retaining walls
9
Circular cell construction
design & installation
Noise and
vibration
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
Contents
Page
12.1
Introduction
1
12.2
Regulatory guidance
2
12.3
Vibration from piling operations
2
12.3.1
The effects of vibration
2
12.3.2
Reducing pile driving vibrations
3
12.3.3
Good practice
3
12.3.4
Vibration level estimation
4
12.3.4.1
Pile presses
4
12.3.4.2
Vibrodrivers
4
12.3.4.3
Impact hammers
5
12.3.5
Estimate limitations
6
12.3.6
Significance of vibration
7
12.3.6.1
Disturbance to people
7
12.3.6.2
Damage to structures
8
12.3.6.3
Compaction and settlement
12.3.6.4
Destabilisation of slopes
10
Noise from piling operations
10
12.4
9
12.4.1
The effects of noise
10
12.4.2
Reducing pile driving noise
11
12.4.3
Good practice
11
12.4.4
Noise level estimation
11
12.4.5
Significance of noise
14
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.1 Introduction
For many years piling and driven piling in particular, has been
perceived as one of the most environmentally disruptive activities
on a construction site. This perception was justified until recent
developments in pile installation technology. The range of methods
now available ensures cost effective pile installation with
appropriate control of noise and vibration.
When heavy construction is to be carried out close to houses,
offices, laboratories or historic buildings, careful planning is
required to ensure that the work proceeds at an appropriate rate, in
a manner that will minimise disruption to the area. The physical
presence of a construction site in a community will cause a degree
of disruption to normal activities, but choosing the most
appropriate technology for each activity will ensure that the
construction period is minimised and that the work proceeds within
acceptable levels of noise and vibration. This will benefit both local
residents and also site workers.
Modern piling techniques can enable noise and vibration to be
eliminated from the installation process for steel piles. When
ground conditions are appropriate, hydraulic pile pressing
technology enables piles to be driven almost silently and without
causing any noticeable vibrations. This technology gives engineers
the opportunity to use steel piling in areas where this type of
construction would previously have been unthinkable. Sheet piling
can now be considered as a first choice material for sites where
environmental disturbance will not be tolerated, such as adjacent
to hospitals, within urban areas, alongside sensitive cable or
pipeline installations or near delicate computer facilities.
Vibrodrivers, which offer the fastest rate of installation of any pile
driving system in granular soils, cause more vibration than pile
presses, but are less disruptive than impact hammers. Engineering
advances have given operators the ability to vary the frequency
and amplitude of vibrations generated by the machine, so that the
system can be tuned to suit the ground conditions. This technology
has also eliminated the severe vibrations generated close to the
pile when the vibrodriver passes through the resonant frequency of
the surrounding ground and buildings during run up and run down.
Impact hammers cause higher levels of noise and vibration than
other types of pile driver, but will drive piles into any type of soil
and may be the only method available for driving into stiff, cohesive
soils or soft rock. The operation of this type of hammer has
changed with advances in technology and over the past half
century, steam has given way to diesel power, which in turn has
been replaced by hydraulic actuation. As a result, modern hydraulic
drop hammers are much less environmentally damaging than their
predecessors. Further reductions in noise levels can be achieved
by the use of shroudings to enclose the area where noise is
generated.
Chapter 12/1
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
Before choosing the pile driving method to use, you need to
consider the circumstances at your site and the levels of noise and
vibration that will be acceptable. Not every site demands silent and
vibration-free pile installation, and cost and time savings may be
achieved if it is acceptable to adopt a less environmentally-sensitive
method of installation. The opportunity to adopt combinations of
driving method should not be overlooked, as it may be feasible to
press piles during more sensitive times of day, completing the final
stage of the drive using an impact hammer.
12.2 Regulatory guidance
Local Authorities may stipulate and impose their restrictions prior
to and during piling operations. To avoid this situation, a preferable
approach is to arrange prior consent. Discussion with the Local
Authority can lead to a ‘Consent to Work’ agreement, usually
embodying the ‘best practicable means’ for the work.
The original Eurocode 3 (1998), Steel Structures, Part 5: Piling,
[ENV 1993:5 (1998)] made specific recommendations on vibration
limits for human tolerance and on thresholds for minor damage to
buildings. Please note that this information has been removed from
the latest revision of EN1993:5 as it is considered by CEN to be
more appropriate in an execution standard. The information has
not yet been relocated but the authors feel it is of value to piling
engineers and is included here.
Although present British Standards do not give rigid limits on levels
of vibration or noise, there are three British Standards that give
helpful guidance on these issues:
BS 5228 parts 1 & 4, (1997/1992),
‘Noise control on construction and open sites’.
BS 6472 (1992),
‘Guide to evaluation of human exposure to vibration in buildings’.
BS 7385 part 2 (1993)
‘Evaluation and measurement for vibrations in buildings’.
12.3 Vibration from piling operations
12.3.1 The effects of vibration
Pile driving using an impact hammer or vibro-driver generates
ground vibrations, which are greatest close to the pile.
Humans are very sensitive to ground vibrations, and it should be
noted that even minor vibrations may attract complaints from
people living or working in the area.
Reports of damage to buildings caused by piling vibrations are
rare. You will find guide values to help avoid cosmetic damage in
ENV 1993:5 (1998), BS5228 pt 4 and BS7385 pt 2.
Heavy ground vibrations may also disturb soils. Piling vibrations
may de-stabilise slopes or lead to compaction settlements of very
loose saturated granular soils.
Chapter 12/2
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.3.2 Reducing pile driving vibrations
Potential problems caused by ground vibrations can be alleviated
or eliminated by:
• Pre-contract planning, to obtain a Consent to Work Agreement,
• Selecting the most appropriate pile driver and working method,
• Forewarning residents of the forthcoming work and its duration
and assuring them of the very low risk of damage to property,
• Carrying out property surveys, before and after your work.
The selection of an appropriate pile driving system is essential if
ground vibrations are to be controlled.
In highly-sensitive locations, very close to existing buildings or
near to historic structures, a pile pressing rig may be used. Pile
pressing systems are vibration-free, and are now effective in most
soils.
For driving into stiff, cohesive soils, an impact hammer may be
needed. Modern hydraulic drop hammers are efficient and
controllable. The combination of a controllable hammer and
vibration monitoring can help to meet vibration limits, while
achieving effective pile installation.
12.3.3 Good practice Excessive ground vibrations can also be avoided by following
good piling practice. Particular care should be taken to ensure
that the pile is maintained in a vertical position by using welldesigned guide frames or a leader. An appropriate size of hammer
should be selected, and the hammer should strike the centroid of
the pile along its axis. Equipment should be in good condition and
piling should be stopped if any head deformation occurs, until the
problem is identified.
Hammering against any obstructions will cause excessive
vibrations. Specialist measures to overcome this problem include:
• Excavation to a depth of 2-3m to avoid old concrete, brick or
timber foundations, or buried services in a previouslydeveloped site.
• Water jetting of dense sands
• Cut-off trenches (although the excavation may cause an
unacceptable risk of ground disturbance).
• Pre-augering to break up hard soils for easy pile driving.
With careful planning and by adopting sensitive piling techniques,
appropriate to your project and the conditions of the site, it is
possible to minimise the vibrations caused by your operations in
the surrounding area.
Chapter 12/3
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.3.4 Vibration level estimation
During the past 20 years, a large number of ground vibrations
have been recorded on piling sites by interested parties from
industry, universities and other research establishments. This body
of knowledge has been formulated into simple empirical equations
for estimation of probable levels of peak particle velocity (ppv)
caused by various piling operations and conditions, and for
probable upper bound levels (ENV 1993:5 1998; Attewell et al,
1992; Hiller & Crabb, 2000).
The equations generally take the form of
v=C
W
r
where v is the estimated ppv in mm/s; C is a parameter related to
soil type and hammer; W is the hammer energy per blow or per
cycle (Joules/blow, or Joules/cycle for vibrodrivers); r is the
horizontal distance from the piling operation to the point of
interest (m). However, it should be emphasised that, while this
equation gives a useful indication of vibrations, it is not an exact
predictor.
Table 12.3.4 The recommendations in ENV 1993:5 (1998) for C values.
Driving method
Ground conditions
Impact
Very stiff cohesive soils, dense granular
media, rock, fill with large solid obstructions
1.0
Stiff cohesive soils, medium dense
granular media, compact fill
0.75
Soft cohesive soils, loose granular
media, loose fill, organic soils
0.5
All soil conditions
0.7
Vibratory
C
12.3.4.1 Pile presses None of the following calculations are necessary if a pile pressing
rig is used to install steel sheet piling, since it causes negligible
levels of vibration provided pile verticality is maintained.
12.3.4.2 Vibrodrivers For vibrodrivers, the calculation may be taken as power rating
divided by frequency, from the manufacturer’s information, with
power in Watts (1 Watt = 1N.m/s) and frequency in cycles/s, so
the resulting unit is N.m/cycle, i.e. J/cycle. The choice of
parameter C depends upon the standard used. ENV 1993:5
recommends C = 0.7 while BS5228 recommends a value of 1.0.
The former is preferred.
Some site records have shown high values of vibrations at low
frequencies during run-up and run-down, and ‘non-resonant’
vibrodrivers have been developed to avoid this behaviour, which
Chapter 12/4
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
has been attributed to a resonant form of ground response. While
there is some support for this explanation, opinions have been
voiced by Hiller (2000) and by Holeyman (2000) that the level of
vibrations is less a function of hammer energy per cycle, than of
the soil resistance to driving.
At the present state of knowledge, it seems appropriate to follow
the ENV 1993:5 procedure in which energy/cycle is used within
the basic empirical equation.
Example 1: A vibrodriver driving and extracting sheet piles in
medium dense sands and gravels. The vibrodriver has a power
rating of 120kW and operating frequency of 38Hz. Calculate ppv’s
at distances of 2m and 10m.
The energy/cycle
= 120000(Nm/s) / 38 (cycles/s, i.e. Hz),
= 3160 Joules/cycle
Take C=0.7 (in accordance with Eurocode 3), and for r=2m,
3160 = 20mm/s
v = 0.7 x √
2
and at r=10m, = 4.0mm/s
The development of high frequency vibro-drivers with variable
eccentric moment has resulted in a very effective driving system
for sensitive areas. Varying the energy input and the frequency
allows the system to be tailored to suit conditions on site.
12.3.4.3 Impact hammers
Calculation of impact hammer energy, W, is by loss of potential
energy in free fall for a drop hammer (mass x gravitational
acceleration x drop height, or, m.g.h.). For a double acting device,
energy = m.g.h. + stored energy, as quoted in the manufacturer’s
literature.
Units are Joules per blow, where 1J = 1N.m.
Example 2: A hydraulic drop hammer driving well-guided steel H
piles in medium clays. The hammer element weighs three tonnes,
and is falling through 0.8m. Estimate ppv’s, v, at distances, r, from
the pile of 2m, 5m and 20m.
Hammer energy
= mass x gravitational acceleration x drop (m.g.h)
= 3000kg x 9.8m/s2 x 0.8m
= 23520 Joules (or N.m)
Take C to be 0.75, then
For r=2m v = 57mm/s
For r=5m v = 23mm/s
and for r=20m v = 6mm/s
Chapter 12/5
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.3.5 Estimate limitations
While the above methods give reasonable estimates of probable
vibration levels, it must be recognised that a number of factors
can cause higher than expected vibration levels, such as
obstructions, mechanical wear or failure, poor support, and
pseudo-resonance of the soil during run-up and run-down. Thus
the estimation methods can be used to give a good indication of
magnitude, but not as an exact and reliable prediction. They are
appropriate for the basis of a Consent to Work Agreement, or for
setting realistic permissible limits to piling vibrations.
In assessing driveability, selecting the size of piling hammer that
achieves a steady rate of penetration is important. This often
leads to a minimum vibration disturbance, taking account of both
intensity and duration.
Before commencing the main works, predicted vibrations can be
checked by driving a test pile using the proposed equipment.
Some examples of records of observed ground vibrations are
given in Table 12.3.5. It should be emphasised that there is
considerable variation in vibrations generated, even from a single
pile being driven by a single hammer, due to changing toe depth,
soil strata, accuracy of blow, upstand of the pile, guide system,
clutch of adjacent pile, meeting of obstructions, and driver
efficiency. Both the curves and the equation tend to overestimate
ppv’s very close to the pile.
Table 12.3.5 Examples of ppv’s recorded on sites.
Hammer and
pile
distances
from pile,
m
radial
ppv, mm/s
transverse
ppv, mm/s
vertical
ppv, mm/s
resultant
ppv, mm/s
Air, 600N,
U pile z=1600 cm3/m
2
8
22
8.6
5.6
3.8
7.2
2.9
2.7
17.0
8.2
5.1
18.0
8.4
6.1
BSP 357, (3T)
Z pile z=2300 cm3/m
2
5
18
10.6
4.5
0.5
7.7
5.0
0.6
22
4.8
0.9
25
6.1
0.9
BSP 357, (5T)
H section
4
17
37
10
13.8
3.3
4.5
2.3
1.0
25.9
11.0
1.2
26.9
15.0
3.5
Vibro MS25H
Z pile z=1700 cm3/m
2
5
16
22
2.8
1.5
28
2.6
1.7
6.8
8.2
2.3
34
9.0
2.5
Chapter 12/6
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.3.6 Significance of vibration
There are at least four consequences arising from ground
vibrations during piling, which may require consideration.
They include:
- disturbance to people
- risk of cosmetic or structural damage to buildings
- compaction settlement of loose granular soils
- destabilization of slopes or excavations.
Guidance on limits for the first two issues is provided by
Eurocode 3: Part 5 (1998) and British Standards, especially
BS5228:part 4 (1992), BS 6472 (1992) and, BS 7385:part 2 (1993).
12.3.6.1 Disturbance to people
Ground vibrations may cause reactions ranging from “just
perceptible”, through “concern” to “alarm” and “discomfort”.
The levels of vibration from piling are not such as to cause risk to
health, (as may occur through prolonged use of a pneumatic
hand-held breaker). The subjective response varies widely, and is
a function of situation, information, time of day and duration.
Table 12.3.6.1 Human tolerance to vibrations from Eurocode 3 :Part 5.
> 1 day
D-
< D< 26 d
6 d-
< D< 78 d
26 d -
Level I
1.5
1.3
1.0
Level II
3.0
2.3
1.5
Level III
4.5
3.8
2.0
Duration D in days
Notes:
1 Level I
Level II
Level III
2
Below this level vibration is likely to be accepted
Below this level vibration is likely to be accepted, with advanced warning.
Above level III vibration is likely to be unacceptable
The above values relate to 4 hours of vibrations per working day.
For different durations of vibrations,
Vtc = V4
2
√(T / T )
r
c
where Tr =16 hours and Tc is the exposure time in hours per day.
3
These limiting values apply for all environments other than hospitals, precision laboratories and libraries,
in which vibrations of up to 0.15 mm/s should be acceptable
Humans are very sensitive to vibrations and the threshold of
perception is of the order of 0.2mm/s of ppv, in the appropriate
range of frequency of 8Hz to 80Hz. BS6472 gives base curves of
vibrations for minimal adverse comment and also vibration dose
values (VDV’s) at which complaints are probable, (VDV’s include
consideration of the duration of the disturbance). The vibration
levels deduced from these recommendations are low. It should be
Chapter 12/7
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
noted that the standards provide guidance on prediction of
probability of adverse comment, but they do not impose a legal
requirement of adherence to any particular vibration threshold
level. This responsibility rests with the Local Authority.
For normal piling operations, the human tolerance to vibration
should be assessed by reference to the table in Eurocode 3 :Part
5 reproduced in Table 12.3.6.1. The level of background vibrations
should not be overlooked when considering reasonable values.
12.3.6.2 Damage to structures
There is little evidence to suggest that vibrations from piling alone
cause even cosmetic damage (minor cracking) to buildings in
good repair (BRE,1983, Malam, 1992, Selby, 1991). However,
buildings in poor condition may offer less resistance to minor
damage. Where property owners are concerned about possible
damage to their buildings, before-and-after surveys should be
conducted to record any additional defects in the building.
BS5228 : pt 4 (1992), and BS7385 : pt 2 (1993), both give helpful
but conflicting guidance on ppv’s above which cosmetic damage
might occur. Impact piling causes intermittent ground vibrations,
and should therefore be considered as transient vibrations, while
ground vibrations during vibrodriving are continuous. The
recommended levels for continuous vibrations are generally taken
as 50 per cent of those for transient values.
Fig 12.3.6.2 Vibration thresholds for domestic and heavy
industrial structures
The recommended threshold limits for intermittent vibrations
acting on residential and industrial buildings from the two
standards are summarised in Figure 12.3.6.2. BS7385 generally
gives more generous limits. BS5228 recommends that the limits
be reduced by up to 50 per cent for buildings showing significant
defects. Where vibrations exceed four times the threshold values,
then structural damage may occur.
Chapter 12/8
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
There is considerable lack of agreement among national codes as
to the advisory threshold ppv’s for avoidance of cosmetic
damage. The structural form of the building should also be
considered when setting limits on vibrations impinging upon
buildings. A building with a stiff ground-bearing raft, or stiff shear
walls, will reduce the ground waves substantially, through
dynamic soil-structure interaction. However, a slender frame will
follow the dynamic disturbance of the passing wave. In addition,
slender suspended floors may show dynamic magnification of the
disturbance if frequencies are similar. BS5228 also recommends
limiting ppv’s in masonry retaining walls to 10mm/s at the base
and 40mm/s at the crest, and gives general recommendations for
consideration of stability. The BS5228 recommended limits for
vibrations impinging on buried services are 30mm/s intermittent
and 15mm/s continuous, but with reductions of 20-50 per cent for
elderly brickwork sewers.
The recommendations from Eurocode 3 :Part 5, reproduced in
Table 12.3.6.2 are generally more conservative, but should result
in the low probability of even minor damage.
Table 12.3.6.2 Tolerance of buildings to vibration,
Eurocode 3: Part5.
Type of property
Ruins, buildings of
architectural merit
Peak particle velocity mm/s
Continuous vibration
Transient vibrations
2
4
Residential
5
10
Light commercial
10
20
Heavy industrial
15
30
Buried services
25
40
12.3.6.3 Compaction and settlement
BS7385-2 (1993) notes the possibility of compaction of loose
granular soils by vibration, which may lead to problems of
differential settlement.
Recent work (Bement & Selby, 1997) has shown that loose granular
saturated soils may compact during prolonged vibration in excess
of some 0.2 to 0.4g of particle acceleration, but to limited depths
below surface of no more than 10m. Compaction is unlikely at more
than about 5m distant from a piling operation unless widespread
liquefaction occurs.
The situations most likely to cause compaction settlement include
extraction of temporary sheet piling directly contiguous to a new
slab or wall when vibrations exceed 1g, and the vibration of
hydraulic fills.
Chapter 12/9
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.3.6.4 Destabilisation of slopes
There is little guidance available on this subject, although a simple
analysis of granular soil slide, Fig. 12.3.6.4, gives a factor of
safety against sliding of F = (resistance to sliding)/(downslope
force) or F = tan φ/tan β, where φ is the soil friction angle and β is
the slope angle. If a transient vertical acceleration is applied, this
increases both downslope force and resistance by the same
fraction, so vertical vibration has no effect. If, however, a
horizontal acceleration applies outward from the slope, then the
downslope force is increased by mass x acceleration, and the
factor of safety is reduced.
Example:
Consider a mass of soil having weight W.
Assume horizontal acceleration = 0.1g, so horizontal force = 0.1W.
Downslope force = W sin β + 0.1 W cos β.
If the slope angle is 20°, then the downslope force increases from
0.34 W to 0.43 W, or an increase of some 27 per cent.
If φ= 35°, the factor of safety is reduced from 1.9 to 1.5.
Fig 12.3.6.4 Slope destabilisation
12.4 Noise from piling operations
12.4.1 The effects of noise
Noise, or unwanted sound, may be generated during pile driving
in the form of sharp repetitive pulses, or a more uniform drone.
Noise in excess of the current threshold level for the workplace
requires the contractor to protect the hearing of workers exposed
to it. Any additional noise imposed upon the public should be
minimised, to avoid disturbance and the risk of damage to
hearing.
Chapter 12/10
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.4.2 Reducing pile driving noise
Pile pressing systems generate negligible noise at the pile, and
only low-level background noise from the diesel power pack,
which can be located away from noise-sensitive areas of the site.
Modern, enclosed hydraulic drop hammers and smooth-running
vibro-drivers are now carefully designed to limit noise, and are
much quieter than older models. By selecting the most
appropriate hammer type and head packing, you can reduce
noise significantly.
12.4.3 Good practice If using vibro-drivers or impact hammers, following a few
straightforward guidelines can help to reduce noise levels.
Noise reduces with distance, so locating noisy plant well away
from the public and site workers, where possible, will limit the
noise disturbance. The impact of steel upon steel is particularly
noisy, so a timber or plastic dolly can be used to cut noise levels.
It may also be possible to muffle some hammers in an enclosure.
A partly-embedded pile may ring when it is struck. To help
prevent this, timber wedges can be used between the pile and
guide frame. Absorbent drapes or packs can also be used.
Noise screens can be constructed between the noise source and
any sensitive properties or locations. Solid obstructions such as
stout timber fences, earth mounds or dense trees may reduce
noise by between 5dB and 10dB.
12.4.4 Noise level estimation
Noise levels experienced in the vicinity of pile driving are a
function of the noise power level, Lw, which is the air pressure
fluctuation at the surface of the equipment (hammer or pile),
expressed in dB, and the distance, R, from the source. A
convenient way to estimate an equivalent continuous A-weighted
sound level over the working day, L aeq , is by the equation
L aeq = Lw - 20 log(R) - 8. dB(A)
Sound power levels for specific plant items should be obtained
from the supplier but impact hammers driving steel sheet or
H piles may typically operate in the range 120 to135 dB. Modern
shrouded hammers – incorporating a noise-reducing enclosure –
may be as much as 10 dB quieter. Pile pressing systems produce
negligible sound levels, with only the power pack generating
low-level noise.
Chapter 12/11
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
Table 12.4.4a Examples of recorded noise levels around piling rigs driving steel sheet piling.
Plant type
Sound
power
level, L w
dB
Primary
observed
noise, L eq
dB
Leq at
10m
dB
Leq at
30m
dB
97@4m
90
80
Hydraulic impact hammers
HPH1200/2400
HH 357-9 BSP
95
85
95@12m
97
87
PTC City 15HF1
93@3m
73
61
ICE216
91@7m
87
74
ICE416
80@7m
77
65
ICE 815
97@7m
94
83
Japanese type Silent Piler
75@1m
55
45
Power Pack
90@1m
70
60
NCK crane tick-over
71@2m
57
47
NCK crane, revving
83@2m
69
59
HH1.5DA
Vibrodrivers
Examples from BS5228
Double acting air hammer (5.6kNm)
134
106
96
Enclosed drop (3 t)
98
70
60
Hydraulic drop (60kNm)
121
93
83
Here are some calculations of noise levels:
Example 1:
Impact hammer driving steel sheet piles with L w = 135dB.
Calculate L aeq values at 2m, 10m, 20m and 50m.
From
L aeq = L w - 20 log(R) - 8. dB(A)
For R = 2m,
L aeq = 135 - 6 -8 = 121 dB(A)
For R = 10m,
L aeq = 107dB(A)
For R = 20m
L aeq = 101dB(A)
For R = 50m
L aeq = 93dB(A)
L aeq = 135 - 20 log(R) - 8.
(Note, for doubled distance, a 6dB reduction occurs)
Chapter 12/12
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
Often a piling operation will run for some 10-50 per cent of the
working day, which reduces the L aeq by a small amount. (Note
that because of the logarithmic relation, a reduction in duration is
accompanied by a much smaller reduction in L aeq ). This effect
can be calculated simply, where L1 is the sound acting over time
t1 compared with working day duration T, from:
{1
L aeq = 10.log T [t 1 .10 L 1/10 ]
}
Example 2: If the noise level of L aeq =107dB(A) at R=10m, from
the previous example is now restricted to 50 per cent of the
working day, then the newly-calculated Laeq becomes
L aeq = 10.log{0.5x10 107/10 } = 104 dB(A)
This is a 3dB reduction, which is just perceptible.
The next condition to consider is when several operations occur
during the day that generate different levels of noise, L1, L2, L3,
each of which lasts for time t1 , t2 , t 3.
These can be evaluated from an expanded form of the previous
equation as
{1
L aeq = 10.log T [t 1 .10 L 1/10 +t 2 .10 L 2/10 +t 3 .10 L 3/10 ]
}
Example 3: Let us assume that three noisy operations occur, for
limited periods of the day illustrated in table 12.4.4b below.
Table 12.4.4b Cumulative noise sources.
Activity
Lw dB
On time
Laeq
at 10m for
t =100%*
Laeq for Cumulative
each alone
Laeq
1
130
20%
102
95
2
126
30%
93
93
3
120
40%
92
92
97
* calculated from earlier equation.
The calculation for the cumulative L aeq comes from the above
equation as:
L aeq = 10.Log { [ 0.2x10 102/10 +0.3x10 98/10 +0.4x10 92/10 ]}
i.e. L aeq = 10.Log { 0.2 x inv.log (10.2) + 0.3 x inv.log (9.8) + 0.4 x
inv. log (9.2) } = 97 dB, as the cumulative equivalent day-long noise
level.
Example 4: The addition of two noise sources, acting concurrently
for the full working day is a simple calculation:
e.g. 95dB and 93dB: L aeq = 10 log [10 95/10 + 10 93/10 ] = 97.1dB.
This is a mere 2.1dB increase above the larger signal.
Chapter 12/13
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
12.4.5 Significance of noise
The two areas of concern about noise are the health and safety of
operators, and annoyance to the public. Prolonged exposure to
noise causes hearing impairment. Exposure to extreme noise
causes instantaneous hearing damage. Employers are normally
expected to assess noise levels, and to respond to different
action levels as follows:
• At the first action level of 85dB (of daily personal noise
exposure, L aeq ): to provide information about hearing risk
and to provide protection on request.
• At the second action level of 90dB: to control exposure to
noise by limiting noise at source, requiring ear protection to be
worn, limiting people’s time of exposure. Noisy areas should
have the hat and ear muff signs displayed.
• At the peak action level of 140 dB (of a single loud noise): to
prevent noise exposure. Such noise can cause instant hearing
damage.
The employer shall reduce, so far as is reasonably practical, the
exposure to noise of the employee. Where necessary, a noise
assessment should be carried out by a competent person with
respect to:
-
Reduction of noise exposure
-
Ear protection
-
Ear protection zones
-
Provision of information to employees.
Current Standards, do not give maximum levels of extraneous
noise. Some suggested limits include:
-
a maximum L aeq during the daytime period of 75dB(A) at one
metre outside a noise-sensitive building in urban areas, or of
70dB(A) in rural areas.
-
Sunday working should be subject to a reduction of 10dB.
-
night-time working should not normally be permitted outside
residential properties, although 40-50dB(A) may be
appropriate.
Normal daytime locations are subject to some level of background
noise. If the noise level increases by 3dB then the change is just
perceptible. If the noise level increases by 10dB then it is
perceived as being twice as loud. An increase of 20dB implies a
tenfold increase in pressure.
It is important to measure ambient noise at any sensitive location,
and to measure the increase in noise caused by piling operations.
An increase in noise level by 10dB is likely to attract some
Chapter 12/14
Piling Handbook, 8th edition (revised 2008)
Noise and vibration from piling operations
objection. With prior warning, a working agreement might be to
limit the increase in noise to some 10 to 20dB(A) above typical
ambient conditions. An office environment of 65dB(A) could be
expected to tolerate 75dB(A).
As with vibrations, a forewarning of the noise and its duration and
intensity will improve people’s tolerance of the intrusion. European
Community Council Directives are under consideration for noise
controls of construction plant.
Chapter 12/15
Product information
2
Sealants
3
Durability
4
Earth and water pressure
5
Design of sheet pile
structures
6
Retaining walls
7
Cofferdams
8
Charts for retaining walls
9
Circular cell construction
design & installation
10
Bearing piles and axially
loaded sheet piles
11
Installation of sheet piles
12
Noise and vibration from
piling operations
13
Useful information
13
Useful
information
1
Piling Handbook, 8th edition (revised 2008)
Useful information
Contents
Page
13.1
Discontinued U piles
1
13.2
Discontinued Z piles
3
13.3
The metric system
4
13.4
Conversion factors and constants
5
13.5
Bending moments in beams
6
13.6
Properties of shapes
7
13.7
Mensuration of plane surface
8
13.8
Mensuration of solids
9
Acknowledgements
10
Piling Handbook, 8th edition (revised 2008)
Useful information
13.1 Discontinued U piles
The table of values below applies to U piles when interlocked
together to form a wall
Fig 13.1
13.1.1 ArcelorMittal sections
Table 13.1.1 ArcelorMittal sections
Section Width Height
b
h
mm
mm
Thickness
t
s
mm
mm
Flat of pan C/S area
f
mm
cm2/m
Mass
Linear
Wall
kg/m
kg/m2
PU 6
600
226
7.5
6.4
335
97
45.6
76
PU 7
600
226
8.5
7.1
335
106
49.9
83.1
PU 8
600
280
8.0
8.0
318
116
54.5
PU 9
600
280
9.0
8.7
318
125
PU 11
600
360
8.8
8.4
258
131
PU 16
600
380
12.0
9.0
302
PU 20
600
430
12.4
10.0
307
PU 25
600
452
14.2
10.0
LS3
500
400
14.1
10.0
Inertia
cm /m
Elastic
modulus
cm3/m
Plastic
modulus
cm3/m
6780
600
697
7570
670
779
90.9
11620
830
983
58.8
98.0
12830
915
1083
61.8
103.0
19760
1095
1336
159
74.7
124.5
30400
1600
1878
179
84.3
140.0
43000
2000
2363
339
199
93.6
156.0
56490
2500
2899
232
201
78.9
157.8
40010
2000
2390
Mass
Linear
Wall
kg/m
kg/m2
Inertia
Elastic
modulus
cm3/m
Plastic
modulus
cm3/m
4
13.1.2 Corus sections
Table 13.1.2a Corus sections
Section Width Height
b
h
mm
mm
Thickness
t
s
mm
mm
Flat of pan C/S area
f
mm
cm2/m
LX8
600
310
8.2
8.0
250
116
54.6
91.0
12863
830
1017
LX 12
600
310
9.7
8.2
386
136
63.9
106.5
18727
1208
1381
LX12d
600
310
10.0
8.3
386
139
65.3
108.8
19217
1240
1417
LX12d10 600
310
10.0
10.0
382
155
72.9
121.5
19866
1282
1493
LX 16
600
380
10.5
9.0
365
157
74.1
123.5
31184
1641
1899
LX 20
600
430
12.5
9.0
330
177
83.2
138.7
43484
2023
2357
LX 20d
600
450
11.2
9.7
330
179
84.3
140.5
45197
2009
2380
LX 25
600
460
13.5
10.0
351
202
95.0
158.3
57656
2507
2914
cm4/m
LX 25d
600
450
15.0
11.0
326
212
100.0
166.7
57246
2544
2984
LX 32
600
460
19.0
11.0
340
243
114.4
190.7
73802
3209
3703
LX 38
600
460
22.5
14.5
337
298
140.4
234.0
87511
3805
4460
Chapter 13/1
Piling Handbook, 8th edition (revised 2008)
Useful information
13.1.2 Corus sections
Table 13.1.2a Corus sections continued
Section Width Height
b
h
mm
mm
Thickness
t
s
mm
mm
Flat of pan C/S area
f
mm
cm2/m
Mass
Linear
Wall
kg/m
kg/m2
GSP 2
400
200
10.5
8.6
266
157
49.4
123.5
GSP 3
400
250
13.5
8.6
270
191
60.1
150.3
GSP 4
400
340
15.5
9.7
259
242
76.1
190.3
6 (42)
500
450
20.5
14.0
329
339
133.0
6 (122)
420
440
22.0
14.0
250
371
122.5
6 (131)
420
440
25.4
14.0
250
396
6 (138.7)
420
440
28.6
14.0
251
419
Inertia
Elastic
modulus
cm3/m
Plastic
modulus
cm3/m
8756
876
1020
16316
1305
1520
38742
2279
2652
266.0
94755
4211
4933
291.7
92115
4187
4996
130.7
311.2
101598
4618
5481
138.3
329.3
110109
5005
5924
cm4/m
Table 13.1.2b Dimensions and properties of interlocked U sections
Section Width
b
mm
Height
h
mm
Thickness
t
s
mm
mm
Flat of pan C/S area
f
mm
cm2/m
Mass
Linear
Wall
kg/m
kg/m2
Combined Section
inertia
modulus
cm4/m
cm3/m
6W
525
212
7.8
6.4
333
109
44.8
85.3
6508
711
9W
525
260
8.9
6.4
343
124
51.0
97.1
11726
902
12W
525
306
9.0
8.5
343
147
60.4
115.1
18345
1199
16W
525
348
10.5
8.6
341
166
68.3
130.1
27857
1601
20W
525
400
11.3
9.2
333
188
77.3
147.2
40180
2009
25W
525
454
12.1
10.5
317
213
87.9
167.4
56727
2499
32W
525
454
17.0
10.5
317
252
103.6
197.4
70003
3216
1U
400
130
9.4
9.4
302
135
42.4
106.0
3184
489
2
400
200
10.2
7.8
270
156
48.8
122.0
8494
850
2B
400
270
8.6
7.1
248
149
46.7
116.8
13663
1013
2N
400
270
9.4
7.1
248
156
48.8
122.0
14855
1101
3
400
247
14.0
8.9
248
198
62.0
155.0
16839
1360
3B
400
298
13.5
8.9
235
198
62.1
155.2
23910
1602
3/20
508
343
11.7
8.4
330
175
69.6
137.0
28554
1665
4A
400
381
15.7
9.4
219
236
74.0
185.1
45160
2371
4B
420
343
15.5
10.9
257
256
84.5
200.8
39165
2285
4/20
508
508
381
381
14.3
15.7
9.4
9.4
321
321
207
218
82.5
86.8
162.4
170.9
43167
45924
2266
2414
5
420
343
22.1
11.9
257
303
100.0
237.7
50777
2962
10B/20
508
171
12.7
12.7
273
167
66.4
130.7
6054
706
Chapter 13/2
Piling Handbook, 8th edition (revised 2008)
Useful information
13.2 Discontinued Z piles
13.2.1 ArcelorMittal sections
t
s
h
b
b
Table 13.2.1 Dimensions and properties of AZ sections
Section
Width
b
Height
h
Flange
t
Web
s
mm
mm
mm
mm
kg/m
kg/m2
Elastic
section
modulus
cm3/m
AZ 34
AZ 36
AZ 38
630
630
630
459
460
461
17.0
18.0
19.0
13.0
14.0
15.0
115.5
122.2
129.1
183.3
194.0
204.9
3430
3600
3780
AZ 36-700
AZ 38-700
AZ 40-700
700
700
700
499
500
501
17.0
18.0
19.0
11.2
12.2
13.2
118.5
126.2
133.8
169.3
180.3
191.1
3600
3800
4000
Linear
Mass
Wall
13.2.2 Corus sections
Table 13.2.2 Dimensions and properties of Frodingham sections
Section
Width
b
Height
h
Flange
t
Web
s
Linear
Mass
mm
mm
mm
mm
kg/m
kg/m2
Elastic
section
modulus
cm3/m
1 BXN
1N
2N
3 NA
4N
5
476
483
483
483
483
426
143
170
235
305
330
311
12.7
9.0
9.7
9.7
14.0
17.1
12.7
9.0
8.4
9.5
10.4
11.9
63.4
48.0
54.8
62.7
82.7
101.0
133.2
99.4
113.5
129.8
171.2
237.1
692
714
1161
1687
2415
3171
1A
1B
2
3
4
400
400
400
400
400
146
133
185
229
273
6.9
9.5
8.1
10.7
14.0
6.9
9.5
7.6
10.2
11.4
35.6
42.1
47.2
61.5
80.1
89.1
105.3
118.0
153.8
200.1
563
562
996
1538
2352
Wall
Chapter 13/3
Piling Handbook, 8th edition (revised 2008)
Useful information
13.3 The Metric System
Linear Measure
1 inch
= 25.4mm
1 foot
= 0.3048m
1 yard
= 0.9144m
1mm
1cm
1m
1 mile
1km
= 1.6093km
= 0.03937 inch
= 0.3937 inch
= 3.2808 feet or
1.0936 yds
= 0.6214 mile
Square Measure
1 sq inch
= 645.16mm2
1 sq foot
= 0.0929m2
1cm2
1m2
1 sq yard
1 acre
1 sq mile
1km2
= 247.105 acres
1mm3
1m3
= 0.000061 cubic in
= 35.3147 cubic ft
or 1.308 cubic yds
1litre
= 1.7598 pints
or 0.22 gallon
1g
1kg
1tonne
= 0.0353 oz
= 2.2046 lb
= 0.9842 ton
1cm3
1cm3/m
1cm4
1cm4/m
=
=
=
=
= 0.8361m2
= 0.4047 hectare
= 259 hectares
1 hectare = 10,000m2
Cubic Measurement
1 cubic inch = 16.387cm3
1 cubic foot = 0.0283m3
= 0.155 sq in
= 10.7639 sq ft
or 1.196 sq yds
1hectare = 2.4711 acres
1 cubic yard = 0.7646m3
Measure of Capacity
1 pint
= 0.568 litre
1 gallon
Weight
1 oz
1 pound
1 ton
= 4.546 litres
= 28.35 kg
= 0.4536 kg
= 1.016 tonnes
or 1016 kg
Section modulus and inertia
= 16.387 cm3
1 inch3
1 inch3/foot = 53.76 cm3/m
1 inch4
= 41.62 cm4
1 inch4/foot = 136.56 cm4/m
Chapter 13/4
0.0610
0.0186
0.0240
0.0073
inch3
inch3/foot
inch4
inch4/foot
Piling Handbook, 8th edition (revised 2008)
Useful information
13.4 Miscellaneous Conversion Factors and Constants
Linear Measure
1 lb (f)
1 pound per linear foot
1 pound per square foot
0.205 pound per square foot
1 ton (f) per linear foot
1000 pound (f) per square foot
1 ton (f) per square inch
1 ton (f) per square foot
100 pound per cubic foot
100 pound (f) per cubic foot
1 ton (f) foot Bending Moment
per foot of wall
=
=
=
=
=
=
=
=
=
=
=
4.449N
1.4881 kg per linear m
4.883kg per m2
1kg per m2
32.69kN per linear m
47.882kN per m2
15.444N per mm2
107.25kN per m2
1602kg per m3
15.7kN per m3
10kNm Bending Moment
per metre of wall
1m head of fresh water
1m head of sea water
1m3 of fresh water
1m3 of sea water
=
=
=
=
1kg per cm2
1.025kg per cm2
1000kg
1025kg
1 radian
Young’s Modulus, steel
Weight of steel
100 microns
=
=
=
=
57.3 degrees
210kN/mm2
7850 kg/m3
0.1mm = 0.004 inch
Chapter 13/5
Piling Handbook, 8th edition (revised 2008)
Useful information
13.5 Bending moments in beams
Type
Cantilever
Freely
Supported
One end fixed,
other end freely
supported
Both ends fixed
Chapter 13/6
Total Load W
Bending
Moment
Maximum
Deflection
Concentrated
at End
WL
WL3
3EI
Uniformly
Distributed
WL
2
WL3
8EI
Concentrated
at Centre
WL
4
WL3
48EI
Uniformly
Distributed
WL
8
5WL3
384EI
Varying Uniformly
from zero at one
end to a maximum
at other end
0.128WL
0.0131 WL3
EI
Concentrated
at Centre
3WL
16
0.00932 WL3
EI
Uniformly
Distributed
WL
8
0.0054 WL3
EI
Concentrated
at Centre
WL
8
WL3
192EI
Uniformly
Distributed
WL
12
WL3
384EI
Piling Handbook, 8th edition (revised 2008)
Useful information
13.6 Properties of shapes
Section
Moment of
Inertia
Ixx
Section
Modulus
Zxx
Radius of
Gyration
rxx
BD3
12
BD2
6
√12
πD4
64
πD3
32
D
4
π(D4-d4)
64
π(D4-d4)
32D
D2+d2
16
BD3-2bd3
12
BD3-2bd3
6D
BD3-2bd3
12(BD-2bd)
BD3
36
BD2
24
√18
B(D3-d3)
12
B(D3-d3)
6D
D3-d3
12(D-d)
D
BD3
3
D
Chapter 13/7
Piling Handbook, 8th edition (revised 2008)
Useful information
13.7 Mensuration of plane surface
Figure
Descripton
Area
Circle
πD
2
Distance ‘y’
to centre
of Gravity
At centre
4
1/2
Triangle
Trapezoid or
Parallelogram
Circular Arc
Circular Sector
Circular
Segment
Ellipse
Parabolic
Segment
Chapter 13/8
1/2
bh
(a+b) h
h (2a+b)
3 (a+b)
br
a
–
1/2
h
3
at intersection
of median lines
ar
ar
b
(r-h)
2
2
π ab
2 bh
3
2br
3a
b3
12 x Area
At centre
2 h
5
Piling Handbook, 8th edition (revised 2008)
Useful information
13.8 Mensuration of solids
Figure
Descripton
Surface area A
and Volume V
Distance ‘y’
to centre
of Gravity
Sphere
A = π D2
V = π /6 D3
At centre
Cylinder
Curved Surface
A = π Dh
V = π /4 D2h
At centre
Pyramid
V=
1
Ah
3
h
4
Above
base
h
4
Above
base
Curved Surface
Cone
πD
A=
4
V=
Wedge
V=
√(4h + D )
2
2
πDh
2
12
bh
(2a+c)
6
h (a+c)
2 (2a+c)
Total Surface
Spherical
Sector
πr x (2h +1/2b)
V =2 π x r h
A=
3
4
( )
r-
h
2
2
3
Spherical
Segment
Spherical Surface
A = 2πrh
π
V= h
2
3
(3r-h)
h (4r-h)
4 (3r-h)
Chapter 13/9
Piling Handbook, 8th edition (revised 2008)
Acknowledgements
ArcelorMittal Commercial RPS would like to express it’s thanks to
the many people who have been involved in the preparation of
this Handbook and for the use of photographs and drawings.
In particular the authors would like to mention
Robin Dawson
Mike Kightley
Eddie Marsh
Dr Alan Selby
who have given us the benefit of their considerable experience.
Care has been taken to ensure that the contents of this publication are accurate at the time of
going to press, but ArcelorMittal Commercial RPS S.à r.l. and its subsidiary companies do not accept
responsibility for errors or for information which is found to be misleading. Suggestions for, or
descriptions of, the end use or application of products or methods of working are for information only
and ArcelorMittal Commercial RPS S.à r.l. and its subsidiaries accept no liability in respect thereof.
Before using products supplied or manufactured by ArcelorMittal Commercial RPS S.à r.l. the
customer should satisfy himself as to their suitability for the intended use.
Chapter 13/10