Load Resistance Behaviour and Installation Assessment of Driven Spun Pile Vigneshwaran Karunanidee Universiti Teknologi Malaysia
Load Resistance Behaviour and Installation Assessment of Driven Spun Pile Vigneshwaran Karunanidee Universiti Teknologi Malaysia
Load Resistance Behaviour and Installation Assessment of Driven Spun Pile Vigneshwaran Karunanidee Universiti Teknologi Malaysia
VIGNESHWARAN KARUNANIDEE
VIGNESHWARAN KARUNANIDEE
APRIL 2010
iii
ACKNOWLEDGEMENT
ABSTRACT
Three (3) numbers of fully instrumented with global strain gauges and
extensometer test Spun piles, namely PILE-A, PILE-B and PILE-C were installed
using 25Ton hydraulic hammer along the coastal area which represent various
subsoil conditions based on soil investigations. The static load test on instrumented
piles provide more information on pile behaviour when loaded such as shaft
resistance at different layer and end bearing, elastic shortening, toe movement,
development of shaft and base resistance during pile displacement. This
information leads to a correlation between SPT-N value and ultimate shaft and end
bearing resistance. Therefore an attempt was made on this study to analyze the load
test results of these instrumented spun piles to develop the correlation for subsoil at
coastal area. It is assessed that the ultimate shaft friction values in the upper soft
clays generally range from about 12 kPa to 20 kPa. Ultimate Shaft friction values
for lower lying materials below soft clays with SPT N values from about 4 to 50
(blows/300mm) range of 2N kPa and a limiting shaft friction value of about 150
kPa. The ultimate end bearing values correlate to about 80N to 120 N kPa. Spun
piles need to be closely observed during installation using hydraulic impact
hammer to avoid any damages on pile and at pile joints. All the piles are fully
monitored during installation using PDA analyzer and the results assessed to verify
the installation technique. The assessment shows that all 3 piles were successfully
installed without integrity problems. A theoretical drivability study also carried out
using GRLWEAP software to provide drivability assessment and compared with
actual drivability of the piles. Results from GRLWEAP is very much similar to data
occurred during pile installation and confirms the drivability of spun piles at this
coastal area without integrity problem. The GRLWEAP software offers variety of
model and analysis option which lead to proper selection of equipments at site.
vi
ABSTRAK
TABLE OF CONTENTS
TITLE i
DECLARATION ii
DEDICATION iii
ACKNOWLEDGEMENT iv
ABSTRACT v
ABSTRAK vi
TABLE OF CONTENTS viii
LIST OF TABLES xi
LIST OF FIGURES xii
LIST OF SYMBOLS xiv
LIST OF APPENDICES xvi
1 INTRODUCTION 1
1.1 Background 1
1.2 Problem Statement 2
1.3 Objectives 3
1.4 Scope 3
1.5 Importance of the Study 4
ix
2 LITERATURE REVIEW 5
3 METHODOLOGY 30
3.1 Introduction 30
3.2 Data Collection 31
3.3 Data Analysis and Results 32
3.4 Summary 33
5.1 Conclusion 46
5.2 Recommendations 47
REFERENCES 48
APPENDICES A – H 50 - 108
xi
LIST OF TABLES
LIST OF FIGURES
LIST OF SYMBOLS
LIST OF APPENDICES
A Subsoil Profile 50
INTRODUCTION
1.1 Background
impact hammer for high loading capacity achievement, and by jacked-in method to
minimize the noise and vibration to surrounding environment in urban areas.
Since the usage of large diameter spun piles driven with hydraulic impact
hammer is being commonly used, and in many occasions, installation difficulties
related with pile breakage due to improper choice of driving equipment and
installation methods have been experienced, an attempt has been made to assess the
installation of Driven Piles and also study its load resistance behaviour in this
project.
There are many methods are studied to verify the load and settlement of piles.
But for the driven spun pile, the most appropriate method to verify the capacity and
pile integrity is static load test and pile driving analyser method. However, it is
3
difficult to verify the shaft friction contributed by each different soil layers and load
transfer behaviour of pile.
Since the large diameter spun piles driven with hydraulic impact hammer is
being commonly used, and in many occasions, installation difficulties related with
pile breakage due to improper choice of driving equipment and installation methods
have been experienced. During construction Stage, verification of suitability of the
pile driving equipment, hammer performance, driving stresses induced in piles, pile
integrity; verification of the capacity at end of driving and with time and pile
settlement need to be observed.
1.3 Objectives
The aim of conducting this study is to analyze spun pile installation by driven
method and load resistance behaviour of driven spun pile. In order to achieve the
purpose of study, three objectives had been identified:
1.4 Scope
(marine Clay) and underlain by residual soils. The spun piles are vertically tested
with both static load test and high strain dynamic test.
The data for this paper is obtained from real time projects conducted in
construction industry. In this case, the piles are fully instrumented and continuously
monitored using Pile Driving Analyser during installation.
LITERATURE REVIEW
The driven piles can installed at site by two methods, by hydraulic impact
hammer and injection method. Injection method preferably replace hammer impact
method at site where development at adjacent site already taken place to avoid noise
and vibration due hammering.
6
Piles are generally used for two purposes; 1) to increase the load carrying
capacity, 2) to reduce the post settlement of foundation. The applied load will be
transferred through soft soil stratum to stiff soil stratum which called end resistance
of pile and also distributing the loads by friction along pile shafts which called shaft
resistance. The figure 2.1 shows typical load distribution of a pile along to its full
length. The transfer of load as shown in figure is extremely difficult to predict and
difficult to quantify by analytical method.
Figure 2.1: Typical distribution of a load along the length of an axially loaded pile.
The soil parameter normally derived from field test and laboratory test to be used in
the static formula.
The pile stiffness for axial loading can be represented by load versus
settlement curve at the top of pile. There are few analytical methods are based on the
theory of elasticity which more possible in solving the behaviour of group of piles
spaced closely under axially loading. This method have solution proposed by
D’Appolonia and Romualdi (1963), Thurman and D’Appolonia (1965), Poulos and
Davis (1968), Poulos and Mattes (1969), Mattes and Poulos (1969) and Poulos and
Davis (1980).
The Second method for obtaining the response of pile under axial load is soil
represent with set of nonlinear mechanism which known as t-z method. This method
was developed by Seed and Reese (1957) and further studies carry out by Coyle and
Reese (1966), Coyle and Sulaiman (1967) and Kraft et al (1981). Figure 2.2 shows a
model of T-Z method where the applied load Q is in equilibrium state by a tip load of
Qb with shaft load Qs. In figure 2.2c the pile is replaced with elastic spring and soil
replaced with set of nonlinear mechanism along the pile and at the tip. From the
hypothetical set of mechanism, the t of the curves representing the load transferred
and the z shows the shaft displacement. It is understood no load will be mobilized
from pile to soil if no relative movement in between them. The movement is depends
on the applied load, position of pile, stress – strain characteristics of pile material and
load transfer curves. The load transfer curve is can only derived with based on full
scale loading test with range satisfied. The non-linear curves shown in figure 2.2d
are predicted by Coyle and Reese (1966) and Coyle and Sulaiman (1967) after few
numbers of successful field test.
8
Where
Where:
Based on field observations, Meyerhof (1976) also suggested that the ultimate
point resistance, Qt, in a homogeneous granular soil (L = Lb) can be obtained from
standard penetration numbers as
where N is an average standard penetration number (about 10D above and 4D below
the pile point)
Figure 2.3: Critical embedment ratio and bearing capacity factors for various soil
friction angle (after Meyerhof, 1976)
11
Generally the simplified soil mechanics methods for bored pile design can be
classified into fine grained soils (e.g. clays, silts) and coarse grained soils (e.g. sands
and gravels).
The ultimate shaft resistance (fsu) of piles in cohesive soils can be estimated
based on the semi-empirical undrained method as follows:
fsu = α x su (2.5)
Where
Based on API method the adhesion factor can be obtain from figure 2.4
where the α value is correlated from the undrained shear strength. Whitaker & Cooke
(1966) proposed that α value will be lies in the between of 0.3 to 0.6 for stiff over-
consolidated clays, while Tomlinson (1994) and Reese & O’Neill (1988) report a
values in the range of 0.4 to 0.9. The α values for residual soils of Malaysia is in
range of 0.8 to 1.0 for soft clay and 0.4 is used for stiff clays is. The value of α to be
used shall be verified by preliminary pile load test.
12
Effective stress method also can be used in obtain the capacity of pile which
will consider the effective stress of pile. This method is representative for the pile
capacity calculation because considering the effect of effective stress change on the
Kse values to be used. This method is more appropriate to be used at site which
consist high water table. The value of ultimate shaft resistance may be estimated
from the following expression:
Where
Although the theoretical ultimate base resistance for bored pile in fine grained
soil can be related to undrained shear strength as follows;
fbu = Nc x su (2.7)
Where
Nc = bearing capacity factor
13
For depth relevant for piles, the appropriate value of Nc value is 9 (Skempton
1951) although due allowance should be made where thi tip of pile penetrates a stiff
layer by only small amount. A linear interpolation should be made between N=6 for
the case of the pile tip just reaching the bearing stratum, up to N=9 for the pile tip
penetrate the bearing stratum by 3 diameter or more.
Experiment results for driven piles in sands below considerable scatter for
value of skin friction and end bearing. The following recommendation for computing
unit value of skin friction and end bearing for piles in sand are consistent with state
of practice, but still subjected to pile load test verification. The API recommendation
for side resistance for driven piles in cohesionless soils is as follows:
And K value of 0.8 was recommended for open ended pile and 1.0 is recommended
for close ended pipe piles.
For the end bearing, the qb may be expressed in terms of the effective vertical
stress σ’v and bearing capacity factors Nq as
qb = σ’v . Nq (2.9)
14
From very beginning, there many attempts been made to find conventional
method for determining the load cab carry by a pile. Dynamic data obtained during
pile driving were used to predicting the capacity. The only data we will obtain during
pile driving is numbers of blows (pile set). Concepts equating the energy delivered
by the hammer to the work done by the piles as it penetrates the soil were used to
obtain pile capacity expression which called pile formulas (dynamic method).
Another method to modelling the pile driving is wave-equation method. This method
is very interesting because of its ability not only in predict load capacity, but also
very useful yield stresses in the piles during driving. The wave-equation method is a
semitheoretical method which reliability in predicting bearing capacity and driving
stresses depends on the accuracy of the pile parameters and soil properties.
15
W. h = R. S (2.10)
Where
W = ram weight
H = ram drop height
R = pile capacity
s = pile penetration per blow.
Pile driving formulas are attractive, and they continue to be widely used in
practice. Unfortunately, the accuracy of these methods is less than impressive.
Although the principle of conservation of energy is certainly valid, pile driving
formulas suffer because it is very difficult to accurately account for all of the energy
losses in a real pile driving situation. The sources of these uncertainties include the
following (Coduto D.P 1994):
1) The pile, hammer, and soil types used to generate the formula may not be
the same as those at site where it is being used.
2) The hammers do not always operate at their rated efficiencies.
3) The energy absorption properties of cushions can vary significantly.
4) The formulas do not account for flexibility of the pile.
5) There is no simple relationship between the static and dynamic strength of
soils.
16
The first computer solution of the wave equation was developed by Smith
(1960). In the wave equation, the pile hammer, helmet, and pile cushion are modelled
by a series of rigid mass elements connected by weightless springs. The springs are
assigned stiffness equal to EA/L for each element. E is the elastic modulus of the
material, A is the cross sectional area, and L is the length of the mass element.
Hammer and pile cushions are represented by additional springs whose stiffness are
calculated from area, modulus of elasticity, and thickness of cushion materials. In
addition, coefficient of restitution (COR) is usually specified to model energy losses
in cushion materials. The COR is equal to one for a perfectly elastic collision which
preserves all energy and is equal to zero for a perfectly plastic condition which loses
all deformation energy. In this way, the computer model accounts for the mass and
flexibility of the hammer-helmet-pile system.
The soil resistance along the embedded portion of the pile and at the pile toe
is represented by both static and dynamic components. Therefore, both static and a
dynamic soil resistance force acts on every embedded pile segment. The static soil
resistance forces are modelled by elasto-plastic springs and the dynamic soil
resistance by linear viscous dashpots. The displacement at which soil changes from
elastic to plastic behaviour is referred to as the soil ‘quake’. In the smith damping
model, the dynamic soil resistance is proportional to the pile element velocity (Vp)
and the static soil resistance (Rs). This can be presented in equation form as:
17
Rd = Js . Vp. Rs (2.11)
where Js is the Smith damping factor. The Smith wave equation model of the ram,
hammer cushion, helmet, pile cushion, pile and soil is given in Figure-2.6.
for incremental time steps until the toe segment starts to rebound. Then, the
permanent penetration of the pile is calculated by subtracting the average value of the
shaft and toe quake from the maximum toe displacement. The pile penetration can be
plotted versus the pile capacity for one point on a wave equation bearing graph. A
typical wave equation bearing graph including driving stress levels is shown in
Figure-2.7.
The first publicly available wave equation software was the TTI program
developed at Texas A&M University. In 1976, researchers at the Case Institute of
Technology developed the WEAP (Wave Equation Analysis of Piles) program. It has
been in the public domain. The WEAP program has since formed the basis for other
more advanced proprietary programs.
1) The blow count (number of blows/ unit length of permanent set) of a pile
under one or more assumed ultimate resistance values and other dynamic
soil resistance parameters, given a hammer and driving system.
2) The axial stresses in a pile corresponding to the computed blow count
3) The energy transferred to the pile.
19
1) The pile’s bearing capacity at the time of driving or re-striking, given its
penetration resistance (blow count)
2) The stresses during pile driving.
3) The expected blows count if the actual static bearing capacity of the pile
is known in advance (i.e. from a static soil analysis).
A bearing graph provides the wave equation analyst with two types of
information:
Following is the methods to interpret the wave equation results obtain from
the analysis:
Check the pile stresses to see whether a safe pile installation is possible
Dynamic measurements of force, velocity and energy at the pile head can
readily be compared to the wave equation computed values in the first pile segment.
Adjustment to the wave equation input parameters can be made depending upon the
agreement between the measured and computed values. This approach is the simplest
use of the data available from dynamic measurement and is an easy way to calibrate
the wave equation thereby reducing the potential error sources.
Pile load test is being carried out traditionally to assess the displacement of
pile when subjected to loading. For this test basically equipments required are
calibrated hydraulic jack or load cell, dial gauges or LVDT’s (Linear Variable
Differential Transformers) and direct levelling using a surveyor’s precise level and
rod referenced to a fixed datum (benchmark) to measure the displacement at pile
head.
Instrumentation is major part in pile testing to develop the load transfer curve
of pile. In the current engineering practise, understanding of the load transfer and
bearing behaviour of piles mainly through analysis of instrumentation full-scale load
tests. For driven piles, the application of instrumentation is more challenging and
difficult due to significant difference in method of pile installation. To overcome this
problem, approximate instrumentation method used by installing either an
instrumented reinforcement cage or an instrumented pipe into hollow core of spun
23
pile and in filled with grout. Figure 2.10 shows typical section of approximate spun
pile instrumentation scheme.
Generally load test will be carried out to measure the displacement of the pile
head when applied with working load. Displacement is very important data during
load test and by conventional test method only the pile head displacement can be
measured will be applied in developing the load settlement curve which will not be
so accurate.
Another method to predict the exact load transfer curve along the pile, fully
instrumentation is used along the pile depth up to toe of pile to assess incremental
strain measurement along full length if pile to determine the distribution of load
transfer from pile to the soil. These provide information on pile tip movements or
deflections along the pile. Instrumentation consists of equipment such as
Extensometer (strain rods) and the electric strain gauges (or vibrating wire strain
gauges).
Using the test data for pile with fully instrumented, the load distribution can
be computed from the measured changes in strain gauges readings and pile
properties. The load transferred at mid-point of each anchored interval can be
computed as follows:
P = ε x Ec x Ac
(2.12)
Where
ε= average change in strain gauges readings
Ec= concrete secant modulus in pile section
Ac= cross section area of pile section
The tangent modulus method also can adopt for measuring the load transfer
of pile by measure the secant modulus of pile from tangent modulus line (Fellenius,
2001). Every measured strain value can be converted to stress via its corresponding
strain- dependent secant modulus.
25
However
σ - Es x ε (2.15)
Therefore
Es = 0.5 Aε+B (2.16)
where
Mt = tangent modulus of composite pile material
Es = secant modulus of composite pile material
σ = stress (load divided by cross section area)
dσ = changes of stress from one load increment to the next
A = slope of the tangent modulus line
ε = measured strain
dε = change of strain from one load increment to the next
B = Y-intercept of the tangent modulus line
The stress strain relation is non linear in contrast, the tangent modulus of
composite material is a straight line. This line can be used to establish the expression
for the secant modulus. Every measured strain value can therefore be converted to
stress and load via its corresponding strain-dependant secant modulus.
26
Two analytical methods are used in computation of the load settlement curve
of an axially loaded pile. The first method is known as theory of elasticity which
been discussed by D’Appolonia and Romualdi (1963), Thurman and D’Appolonia
(1965), Poulos and Davis (1968), Poulos and Mattes (1969), Mattes and Poulos
(1969) and Poulos and DFavis (1980) on methods derived from this theory. These
methods use Mindlin’s (1963) equations for stress and deformations at any point in
the interior of semi-infinite, elastic and isotropic solids resulting from a force applied
at another point of the solids. The displacement of pile is calculated by applying the
influences of load transfer in the shaft friction and tip resistance. This method takes
the stress distribution within the soil into consideration, so this method applicable in
solving the behaviour of group piles. (Poulos, 1968, Poulos and Davis, 1980). This
method also is oversimplified by allowing the elasticity based methods to work under
condition where soil stratified into different layer, strength and compressibility.
Figure 2.11 shows typical mechanics of loaded pile where axial load applied
at pile head and undergoes displacement. Based on the figure the strain in the
elements due to axial load P is calculated by neglecting the second order term dP:
dz P
=− (2.17)
dx EA
27
dz
P = − EA p (2.18)
dx
where
P = axial force in the pile
E = Young Modulus of the pile material
Ap = cross section area of the pile
The total load transfer through an element dx is expressed by using the modulus µ in
the load transfer curve Figure 2.12a.
where
l = circumstance of a cylindrical pile or the perimeter encompassing an H-pile
µ = modulus in the load transfer curve in Figure 2.12a
Pile tip resistance is the product of a secant modulus υ and the pile-tip
movement ztip (See Figure 2.12b)
Equation 2.21 is the basic differential equation that must be solved. Boundary
condition at the tip and the top of the pile must be established. The boundary
condition at tip of the pile is given by equation 2.22. At top of the pile, the boundary
condition may be either a force or a displacement.
29
METHODOLOGY
3.1 Introduction
The study was conducted on available data from various sources. Foremost,
data collected are from fully instrumented driven spun pile and pile subjected to high
strain dynamic testing (PDA). The site selected is at coastal line (marine stretch)
which consists of soft marine clay up to 20-30m depth.
Spun Piles
Stage 3 - Summary
The first stage of this study is including identification of sites that used
instrumented driven spun pile as foundation for the structure at Marine clay formation.
Based on the geological map, the marine soft clays fall under Quaternary formation
which consists of Marine and continental deposits with clays, silts, sands, peat with
minor gravel. This quaternary formation generally falls at coastal area of peninsular
Malaysia. The piles selected were pre-cast pre stressed spun concrete piles driven closed
ended with a standard X-pointed shoe. During driving, the piles were monitored
32
continuously for driving stresses and pile integrity using a Pile Driving Analyser.
Subsequently, static load test was performed on the preliminary test piles that were
instrumented with Global Stain gauges within the annulus of the closed ended piles and
the following are obtained:
For the drivability assessment of spun pile, the required data are soil
investigation results (SPT N-Values), continuous PDA monitoring results, driving
equipment details and lab test results on SI data. For the load transfer behaviour
analysis, the driven spun piles with fully instrumented with strain gauges and subjected
to static load test are isolated. The information required from instrumented spun piles is
strain gauge and rod extensometers readings and SI data. The piles are tested to failure
which will provide the most useful information in terms of ultimate shaft friction of
different soil strata, ultimate end bearing and load-transfer characteristics that can
utilized in the assessment of design working piles. All the results and data are completed
for analysis purpose.
The second stage of this study is analysis of the data that obtained from the sites.
Two types of analysis are proceeded to achieve the study’s objectives. For the first
objective of the study, the readings from instrumented test pile such as tell-tale
extensometer readings and strain gauge readings analysed. The load distribution is
calculated from the measured changes in global strain gauge readings and pile
properties. The ultimate average load resistance at shaft and base from instrumentation
readings analysis for different soil profile plotted against SPT N value (SI data).
33
3.4 Summary
The third and final stage of the study is draw a conclusion based on the results of
the analysis. The result that was derived from the analysis carefully studied based on the
objectives of the research. The correlation of ultimate shaft resistance to SPT N-values
and load transfer behaviour for shaft and base of the spun piles in soft Marine clay
formation produced. The drivability of spun pile on specific formation fully analysed
and comparison provided for theoretical assessment against actual driving data.
Recommendations also included to improve the quality of the tests and results and to
refine the tests for more useful findings in the future.
The closeness and the deviation between the results obtain checked. There are
some deviations between the results and the causes are identified. Suggestion also
included to improve the quality of the tests and to refine the tests for better comparison
in the future.
CHAPTER 4
Three (3) numbers of preliminary test piles were carried out in the marine
stretch of the proposed bridge, namely PILE-A, PILE-B and PILE-C. The piles were
pre-cast pre-stressed spun concrete piles driven closed ended with a standard X-
pointed shoe. During driving, the piles were monitored continuously for driving
stresses and pile integrity using a Pile Driving Analyzer. Subsequently, static load
test was performed on the preliminary test piles that were instrumented with Global
Stain gauges within the annulus of the closed ended piles. Following Table 4.1
describes the properties of spun pile used:
Subsoil profiles at the test pile location PILE-A, PILE-B and PILE-C are
shown in Appendix A. Boreholes were carried out close to PILE-A, PILE-B and
PILE-C locations namely, BH-MLTA, BH-MLT-B and BH-MLT C. Based on the
boreholes carried out adjacent to the test pile locations, the sub-soil conditions can be
summarized as follows:
The instrumentation scheme adopted for the instrumented test piles – PILE-
A, PILE-B and PILE-C is shown in appendix B, C and D respectively. The
instrumentation comprises of global strain gauges and extensometers that can be
interpreted to obtain load distribution with depth, shaft friction, end bearing and load
transfer curves (shaft friction versus mid-shaft movement and end bearing versus pile
toe movement).
fsu = Ka x Na (kPa)
Where:
Ka = ultimate shaft resistance factor (1.7-3)
Na = SPT-N value along pile shaft
Fbu = Kb x Nb (kPa)
Where:
Kb = Ultimate end bearing resistance factor (250 – 400 for driven piles)
Nb = SPT-N Value at end of pile
37
1) Assuming the strains in steel is same as strains in concrete; load at strain level
is computed as follows:
Pave = εApEc
Where
3) The load transfer curve for shaft and base is generated as per following
method:
a) Pile was divided into segments between the strain gauge levels. For each
segment, the mid-segment movement of the pile shaft was linearly
interpolated between the movement of the bottom of segment and the top
of segment that are obtained using extensometers.
38
b) The same process was repeated for the subsequent head load and head
settlement and the corresponding strain gauge and extensometer readings
along the pile length. Therefore for each pile, the load transfer curve for
shaft was generated for each pile segment and one load transfer curve for
the base.
Appendix B, C and D shows the load transfer characteristic of shaft and base of these
three piles.
The load distribution with depth for PILE-A, PILE-B and PILE-C is given in
appendix B, C and D respectively. Following are the summary of interpreted ultimate
shaft friction values based on the test pile results:
Based on the results obtained from instrumented test pile following is the discussion
on the results:
1) The ultimate shaft friction values in the upper soft clays generally range from
about 12 kPa to 20 kPa.
2) Shaft friction values for lower lying materials (predominantly Silty SANDS /
SANDS and with some mixed layers of silty CLAY and with SPT N values
40
3) Few readings show unpractical values and discarded during the analysis of
the instrumentations.
The piles are displaced during the maintain load test and it is assessed that the
load was fully mobilised in the piles. It is assessed that the load at final level of
segment is sustained by end bearing. The load sustained by end bearing is divided
41
into cross section of base of pile to compute the end bearing resistance. The
interpreted end bearing values for all three piles are summarized as follows:
Table 4.8: Base friction for test piles PILE-A, PILE-B and PILE-C
Test Pile No. Average SPT N value for depth of Ultimate end bearing
3 x pile diameter below toe of pile (kPa)
PILE-A 35 2740
PILE-B 50 6142
PILE-C 30 2418
1) The ultimate end bearing values correlate to about 80N to 120 N kPa where N
is the uncorrected SPT N value. This range is low in comparison to the
recommendations in literature for driven piles in silty SANDS/SANDS (300
to 400N). When overburden correction is applied on the SPT N values, the
ultimate end bearing values correlate to about 140 to 270 N (applying Liao
and Whitman 1986 method) and 170 to 350 N (applying Skempton 1986
method) where N is the corrected SPT N value for overburden. The ultimate
end bearing correlation with SPT-N value is shown in figure 4.2.
42
Figure 4.2: Correlation between Ultimate End Bearing and SPT-N Values
4.3.1 Pile driving stresses and pile integrity using continuous PDA monitoring
All three piles were continuously monitored during installation to control the
stresses developed in the piles. The PDA results obtained are shown in appendix E.
The pile driving stresses and the pile integrity obtained by continuous monitoring
using pile driving analyzer (PDA) during driving of the preliminary test piles
summarized as follows in table 4.9:
43
Depth at Energy
Compr
which pile Drop Transferred Tension Pile
ession
Pile No. was Height (max) Stress Integ
Stress
monitored (mm) (ton.m) (MPa) rity
(MPa)
(m)
100 -
PILE-A 11 to 43 12.28 4 to 23 0.4 – 6.2 Good
600
100 -
PILE-B 26.5 to 47 13.42 6 – 30 0.8 – 8.5 Good
600
PILE-B 200 -
47 to 57 15.57 15 - 26 1.8 – 7.1 Good
Restrike 1000
100 -
PILE-C 8.5 to 33.5 13.79 5 - 33 0.9 – 9.1 Good
800
From the PDA results, the following is the discussion of the results:
3) The integrity of the piles is satisfactory and the piles had no apparent damage.
44
1) All the stresses developed in GRLWEAP are similar to the stresses developed
during pile driving. The actual compressive stresses and capacity picked up
by PDA is showing lesser than assessed by GRLWEAP software except for
capacity of Pile-C. The GRLWEAP software also determines the set criteria
required to achieve the designed load and length required.
2) The tensile stress developed in the GRLWEAP is too low if compare to the
tensile stress measured by PDA at site during pile driving.
45
3) The further study carried out using 10 Ton hammer shows that the piles can
be driven with limited stresses in pile. However the piles can’t penetrate
certain soil layer due to the insufficient of hammer energy. This lead to the
lower working capacity of piles. Driving large diameter piles using 10 Ton
hammer will consume more time and will delay the construction progress.
All the GRLWEAP analysis results for 25Ton hammer, comparisons of PDA and
GRLWEAP and GRLWEAP results for 10 Ton hammer are appended in appendix F,
G and H respectively
CHAPTER 5
5.1 Conclusion
The results obtained from the analysis and assessment carried out and
discussion in chapter 4, the following can be concluded:
1) The correlation between ultimate shaft and base resistance and SPT-N value
is obtained based on the analysis instrumented test pile results in this study.
The following correlation can be used as design guideline for future driven
spun pile (closed ended) at this coastal area:
a. For the Soft Marine Clay with SPT-N value equal or lesser than 4
blows/300mm, ultimate shaft friction is
fsu = 12 to 20 kPa
b. For lower lying materials below soft clays with SPT-N value more
than 50 blows/300mm, ultimate shaft friction is
c. For the lower lying material below Soft Marine Clay, the ultimate end
bearing values correlate to about
2) The large diameter spun piles are can be driven to set by driven method with
hydraulic hammer into deeper level without any integrity problem to the spun
piles.
3) The GRLWEAP analysis confirms the stresses developed in piles and shows
that large diameter spun pile can be driven using hydraulic hammer.
4) All the future large diameter spun pile at this coastal area can be design and
driven using GRLWEAP software as guideline.
5) The drivability of spun piles using different type of equipments also can be
tested in the GRLWEAP in advanced to avoid construction problem.
5.2 Recommendations
2) The tension stresses obtained at site during PDA test is significantly higher
than GRLWEAP result. Further studies can be carried out to resolve this
issue.
3) The correlation of base resistance is based on 3 piles only. More test piles
need to be carried out to obtain the reasonable correlation value for end
bearing.
Bengt H. Fellenius (22 & 23 April 1998). Recent Advance in The Design of piles for
Axial Loads, Dragloads, Downdrag, and Settlement. ASCE and Port of NY&NJ
Seminar.
Bengt H. Fellenius (14-16 February 2002). Determining the True Distributions of Load
in Instrumented Piles. ASCE International Deep Foundation Congress.
Geotechnical Special Publication No. 116. Orlando, Florida.
Faisal Hj.Ali, Lee Sieng Kai (2007), A new instrumentation method for driven
prestressed spun concrete piles, EJGE
Fellinius B.G. (1980). The analysis of results from routine pile loading tests. Ground
Engineering, London, Vol. 13, No. 6.Fellinius B.G. (1989). Tangent modulus of
piles determined from strain data. The American Society of Civil Engineers,
ASCE, Geotechnical Engineering Division, the 1989 Foundation Congress, F. H.
Kulhawy, Editor, Vol. 1.
Goble, G.G., Rausche, F., And Likins, G (1980). The Analysis of Pile Driving – A State
of the Art. Proc. Of the 1st International Conference on Application of
Stresswave Theory to Piles. Balkema, Stockholm Sweden.
Hannigan,P.J, Goble, G.G, Thendean, G., Likins, G.E and Rausche,F.(1998), Design and
construction of driven pile foundation, Volume 1 & 2, FHWA H1-97-013,
Washington D.C
Lymon C.Reese, William M. Isenhower, Shin-Tower Wang (2006) Shallow and Deep
Foundation, USA, John Wiley & Sons.
Patrick J Hannigan (1990) Dynamic Pile Monitoring and Analysis of Pile Foundation
Installations, Deep Foundations Institute.
Pile Dynamics, Inc (2000). Capwap for Window – Manual 2000. Ohio, USA. Page 2-1
to 2-2.
Poulos H.G. and Davis E.H. (1980). Pile Foundation Analysis and Design. Wiley &
Sons, New York. (reprinted by Krieger Publishing, Malabar, Florida, 1990).
Randolph M.F. and Wroth C.P. (1978). Analysis of deformation of vertically loaded
piles. Journal of the Geotechnical Engineering Division, ASCE, Vol. 104 (GT12).
Seed H. B., and Reese L. C. (1957). The Action of Soft Clay Along Friction Piles
Transactions. American Society of Civil Engineers, New York, NY, Vol 122.
W.G.K Fleming et al (1992), Piling Engineering, Halsted press, John Wiley & Sons.
APPENDIX A
SUBSOIL PROFILE
51
PILE-A
52
PILE-B
53
PILE-C
54
APPENDIX B
PILE-A
55
INSTRUMENTATION SCHEME
PILE-A
56
PILE – A
57
PILE-A
58
59
60
APPENDIX C
PILE-B
64
INSTRUMENTATION SCHEME
PILE-B
65
PILE-A
66
PILE-B
67
68
69
APPENDIX D
PILE-C
73
PILE-C
74
PILE-C
75
PILE-C
76
77
78
APPENDIX E
PILE-A
83
PILE-A
84
PILE-A
85
PILE-B
86
PILE-B
87
PILE-B
88
PILE-C
89
PILE-C
90
PILE-C
91
APPENDIX F
PILE-A
93
PILE-B
94
PILE-C
95
APPENDIX G
PILE-A
97
PILE-A
98
PILE-A
99
PILE-B
100
PILE-B
101
PILE-B
102
PILE-C
103
PILE-C
104
PILE-C
105
APPENDIX H
PILE-A
107
PILE-B
108
PILE-C