Failure

CASE STUDY
ON
Foundation Failures
by
Dr.S.R.Gandhi
Professor
srgandhi@iitm.ac.in
Geotechnical Engineering Division

Department of Civil Engineering
Indian Institute of Technology, Madras
MAJOR CAUSES OF FAILURES
Soil Data inadequate/inaccurate

Imposed load not considered adequately
Wrong Design Concept
Inadequate or Improper Dewatering
Slope Erosion
Unexpected Situation
Inadequate Soil Data
Dewatering Difficulties
Uplift Force
Due to Lateral Forces
Unforseen Loading
Precast roof of 55 m span, 240 m long (40,000 t capacity) urea
storage silo for Chambal Fertilizers and Chemicals Limited
at Gadepan, Kota
Inadequate End-bearing in Piles
Photo-1
Photo- 2
Photo- 3
Photo- 4
Photo- 5
Photo- 6
Failure of Slopes
Failures in Ash Dykes
Surprises
7th Cargo Berth (Contd.)
Sand Drains
Piles
TYPICAL SECTION OF CARGO BERTH
Prof.V.S.Raju, IIT Madras

7th CARGO BERTH AT KANDLA PORT
65 m wide x 250 m long RCC Deck Structure supported on

Bored RCC Piles, 1.0 m dia @ 5 m c/c both ways.
190 m wide X 250 m long open stack area to store cargo

up to loading Intensity of 200 kN/m2.
Sand Drains and Preloading for Ground Improvement.
Measurement of pore water pressures and lateral

displacements.

LAYOUT OF CARGO BERTH

SLIP SURFACE

SLIP FAILURE DURING CONSTRUCTION
With 50% of the piles installed, a deep seated slip

failure occurred.
Damage to a large number of piles.
Head displacement of 8 piles as high as 2.5 m
which meant breakage of the piles.
Nearly 80 piles had top displacement exceeding 30 cm.
Theoretical analysis shows permissible displacements
without structural damage as 30cm.

REASONS FOR FAILURE
Instability of the clay slope under the weight of the
fill placed for making the construction possible.
Lateral movement of the slope under the influence
of the preloading:
The piezometers did not work function properly,
The settlement observation clearly indicated the
lateral displacements which was not taken
notice of,
The direct measurement of the lateral
displacements using the slope indicator were
not taken as the instrument (probe) was
nonfunctional for one year.
REMEDIAL MEASURES
Further fill to facilitate construction of piles was
stopped.
Further pile installation was done using end on
method.
Integrity tests were carried out on the displaced
piles to find the extent of damage.
About 80 replacement piles were installed adjacent
to the displaced piles wherever displacement
exceeded 30 cm.
Connecting beams suitably designed to take care of
the eccentricity.
REMEDIAL MEASURES
The dredging operation carried out in stages with careful

monitoring of the slope under the Berth after each stage.
Slope under the Berth was artificially made by water

jetting to prevent further instability.
The Berth was successfully constructed and made

operational. This withstood Jan 2001 earthquake very
well.

Construction of 8th Cargo Berth
Based on the experience of 7th Berth construction,
careful monitoring was recommended
This comprised of the following:
Settlement Platforms
Electrical Piezometers
Magnetic Settlement Gauges
Inclinometers to check lateral movements
Prof. V.S.Raju, IIT Madras
EARTH QUAKE DAMAGE AND REPAIR OF
BERTH AT KANDLA PORT
Earthquake of M6.9 with epicenter 40Km south of

Kandla.
Lateral movement of soft clay slopes below the berth
has lead to damage of cargo berths 1 to 5 with actual
length of 1250m.
Damage was essentially to piles.
Horizontal cracks (1 mm width) in 50% of vertical

piles (1500 out of 3000 piles).
Shearing and crushing of raker piles at the junction
with the tie beam.
+15.93
+15.625
BERTH
TRANSIT SHED
+9.83
+9.146
+3.049
5
: 1.
P E1
S LO
G
IN :3 500 DIA PILE
ST PE 1
E XI SLO
ED
IGN
DES
-14.94
-28.0
6100 9150 9150 9150 9150
22873
TYPICAL CROSS SECTION OF CARGO BERTH

G.L
+5.60 VERY SOFT CLAY
2
C = 5 KN/m
+3.0 N.M.C L.L
SOFT CLAY
C = 15 KN/m2
-5.0
FINE SAND
MEDIUM SAND
COARSE SAND
-20.325
STIFF CLAY
N.M.C = P L
-26.425
SANDY COARSE GRAVEL
-27.95 SANDY MEDIUM GRAVEL
-29.475
FINE SAND
-34.05
SOIL PROFILE FOR BERTHS 1 - 4

Earth Quake Damage and Repair (Contd..)
REASONS FOR FAILURE

The vertical piles are not designed to take any
horizontal forces.
As per the design horizontal forces to be taken by

raker piles.
Change in the slope from 3H:1V (original design)

to1.5H:1V (which is not stable)
Under seismic conditions instability of slope increases,
in turn exerts higher horizontal forces on piles.
Combination of the Lateral pressure on the pile from soil
and seismic force due to mass of the deck and stored
material.
Earth quake damage and repair (Contd.)
RESTORATION OF BERTH
Providing a row of 1200mm RCC Bored vertical piles.
Additional piles will take, 50% of horizontal force and

70% of lateral force exerted due to slope instability.
50mm micro concrete (Renderoc UW) cover on the

cracked portion of the old piles over a length of 1m from
top of pile.

+9.146
500 PILE
1200 PILE
-14.9 PROPOSED
EXISTING
A B C D E F G H
28.0
-
CROSS SECTIONS WITH NEW PILES

ISSUSES FOR NEW PROJECT
Low lying area with marshy land.

Removal of thick vegetation.
Removal of Slushy Soil.
Lowering of ground water (?).
Placement of fill.
Selection of fill material.
Difficulty of controlled compaction.

Failure

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CASE STUDY

Geotechnical Engineering Division

Soil Data inadequate/inaccurate

Prof.V.S.Raju, IIT Madras

65 m wide x 250 m long RCC Deck Structure supported on

190 m wide X 250 m long open stack area to store cargo

Sand Drains and Preloading for Ground Improvement.

Measurement of pore water pressures and lateral

Prof.V.S.Raju, IIT Madras

LAYOUT OF CARGO BERTH

Prof.V.S.Raju, IIT Madras

Prof.V.S.Raju, IIT Madras

SLIP FAILURE DURING CONSTRUCTION

With 50% of the piles installed, a deep seated slip

Prof.V.S.Raju, IIT Madras

The dredging operation carried out in stages with careful

Slope under the Berth was artificially made by water

The Berth was successfully constructed and made

Prof.V.S.Raju, IIT Madras

Earthquake of M6.9 with epicenter 40Km south of

Horizontal cracks (1 mm width) in 50% of vertical

TYPICAL CROSS SECTION OF CARGO BERTH

Prof.V.S.Raju, IIT Madras

SOIL PROFILE FOR BERTHS 1 - 4

Prof.V.S.Raju, IIT Madras

REASONS FOR FAILURE

As per the design horizontal forces to be taken by

Change in the slope from 3H:1V (original design)

Providing a row of 1200mm RCC Bored vertical piles.

Additional piles will take, 50% of horizontal force and

50mm micro concrete (Renderoc UW) cover on the

Prof.V.S.Raju, IIT Madras

CROSS SECTIONS WITH NEW PILES

Prof.V.S.Raju, IIT Madras

Low lying area with marshy land.

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