Implementation of Laterally Loaded Piles in Multi-Layer Soils
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Transcript of Implementation of Laterally Loaded Piles in Multi-Layer Soils
Purdue UniversityPurdue e-Pubs
JTRP Technical Reports Joint Transportation Research Program
2009
Implementation of Laterally Loaded Piles in Multi-Layer SoilsMonica PrezziPurdue University
This document has been made available through Purdue e-Pubs, a service of the Purdue University Libraries. Please contact [email protected] foradditional information.
Recommended CitationPrezzi, M. Implementation of Laterally Loaded Piles in Multi-Layer Soils. Publication FHWA/IN/JTRP-2009/40. Joint Transportation Research Program, Indiana Department of Transportation andPurdue University, West Lafayette, Indiana, 2009. doi: 10.5703/1288284314332.
Implementation of Laterally Loaded Piles in Multi-Layer Soils
JTRP SPR- 3261Final SAC meeting
SAC membersMir Zaheer and Keith Hoernschemeyer
Purdue University
1
Introduction
Analysis developed for the design of laterally loaded piles in multi-layer soil using energy principles (SPR 2630)
Analysis validation for piles in sandModel pile lateral load tests
(single piles and pile groups)DrivenPreinstalledJacked
2
Objectives
Study the response of piles subjected to lateral load through a series of model pile load tests
Evaluate the effect of pile installation (driven, jacked and preinstalled) on pile response
Compare the model pile experimental results with results from the analysis for preinstalled model piles
3
General scope of work
Task 1
Task 2
Task 3
Task 4
Task 5
Purchase of sensors
Fabrication of piles and pile caps
Fabrication of jacking system
Performance of model pile load tests
Validation of the analysis
4
ContentsModel pile testing planModel pile testing
Sample preparation Soil tank Sand pluviator
Instrumented model pile Driving system Preinstallation method Jacking system
Installation of piles for pile group testing Lateral loading system
Comparison of test and analysis results Single piles Pile groups
Summary and Conclusions
5
Model pile testing plan
Model Pile Test
Laterally Loaded Piles
Single piles
Driven Preinstalled Jacked
Pile groups
Driven (4 piles)
6
Pile Installation Soil Condition Relative Density
Dense sand DR ≈ 90%
Medium dense sand DR ≈ 60%
Loose sand DR ≈ 40%
Multi-layer DR ≈ 60%, 90 %
Dense sand DR ≈ 90%
Medium dense sand DR ≈ 60%
Dense sand DR ≈ 90%
Medium dense sand DR ≈ 60%
Loose sand DR ≈ 40%Dense sand DR ≈ 90%Medium dense sand DR ≈ 60%Loose sand DR ≈ 40%Multi-layer DR ≈ 60%, 90 %
Driven
Driven
Preinstalled
Jacked
Single pile
Group piles
Model pile testing plan
7
ContentsModel pile testing planModel pile testing
Sample preparation Soil tank Sand pluviator
Instrumented model pile Driving system Preinstallation method Jacking system
Installation of piles for pile group testing Lateral loading system
Comparison of test and analysis results Single piles Pile groups
Summary and Conclusions
8
Guide rod
Model pile
Hammer
Soil tank Soil tank (D=2m, H=1.6m)
Reaction beamsupport
Guide arm for pile driving (rotatable and extensible)
9
Soil tank
Holes for draining sand
Reaction beam(detachable)
Guide arm for pile driving
Open
Close
10
Diffuser sieves
Gantry
Soil tank
Sand pluviator Large-scale sand pluviation system (D=2m)
Hoist for adjusting height
Shutter plate
11
Holes for sand pluviation
Top of pluviator
Two sieve layers
Sand pluviator
12
Sand pluviator Schematic view and photo of sand pluviator
Depositedsand
Rainingsand
Falling sand jets
Sandsupply
Chains
Diffusersieves
Shutter plate
Hoist
13
Sample preparation
Top view of pluviator
Sand pluviation
14
Draining sand Draining sand after the test
15
ContentsModel pile testing planModel pile testing
Sample preparation Soil tank Sand pluviator
Instrumented model pile Driving system Preinstallation method Jacking system
Installation of piles for pile group testing Lateral loading system
Comparison of test and analysis results Single piles Pile groups
Summary and Conclusions
16
Instrumented model pile Smooth steel pipe (D=3cm, L=120cm, t=0.2cm)
Collected wires at pile head Closed-ended pile base
17
Instrumented model pile
22 strain gauges
Closer near the base (higher load transfer rate)
Load cell-shaped pile base
18
Driving System Installation of driven pile
Filled soil tank
Pile Cap
Hammer
Guide Rod
Preinstallation of model pile
Preinstalled pile
20
Pile jacking system
21
Pile jacking system Max. rate = 5 cm/min
Model Pile
Motor
Screw Rod
22
Installation of Group piles Setup
1
23
44 Piles
Pile driving order
Pile driving guide (Wooden Box Frame)
& Steel Cap
23
Lateral loading system
Single pile
Pile groups
24
ContentsModel pile testing planModel pile testing
Sample preparation Soil tank Sand pluviator
Instrumented model pile Driving system Preinstallation method Jacking system
Installation of piles for pile group testing Lateral loading system
Comparison of test and analysis results Single piles Pile groups
Summary and Conclusions
25
Test results: Single pile
Sand typeQlat, 5%
(kN)Qlat, 10%
(kN)Qlat, 20%
(kN)
Dense 0.42 0.65 0.92
Medium dense 0.24 0.36 0.54
Loose 0.19 0.29 0.44
0
2
4
6
8
10
12
14
16
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Lateral Load (kN)
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Dense sandMedium dense sandLoose sand
Lateral load - deflection curves (driven pile)
Ultimate lateral loadsQlat,5%,
Qlat,10%
Qlat,20%
corresponding to lateral pile head deflections of 5, 10 and 20 % of the pile diameter
1.0 kN = 225 lb
26
Test results: Single pile
h: horizontal distance between gauges
Tε : tensile straincε : compressive strain
Bending moment
( )T cEIMhε ε⋅ −
=
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4
Bending Moment (kN-m)
Dep
th (m
)
0.1 kN 0.2 kN0.3 kN 0.4 kN0.5 kN 0.6 kN0.7 kN 0.8 kN0.9 kN 1.0 kN1.1 kN 1.2 kN
Dense sand (DR=91%) Medium dense sand (DR=59%) Loose sand (DR=38%)
EI: bending stiffness of pile Rollins et al. (1998)
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4
Bending Moment (kN-m)
Dep
th (m
)
0.1 kN 0.2 kN0.3 kN 0.4 kN0.5 kN 0.6 kN0.7 kN 0.8 kN0.9 kN
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4
Bending Moment (kN-m)
Dep
th (m
)
0.1 kN 0.2 kN0.3 kN 0.4 kN0.5 kN 0.6 kN
Bending moment profiles (driven pile) 1.0 kN-m = 0.738 lb-kips
0
2
4
6
8
10
12
14
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Dense sandMedium dense sandLoose sand
27
Test results: Single pile
Sand typeQlat, 5%
(kN)Qlat, 10%
(kN)Qlat, 20%
(kN)
Dense 0.51 0.71 0.97
Medium dense 0.32 0.42 0.59
Loose 0.21 0.31 0.47
Lateral load - deflection curves (jacked pile)
1.0 kN = 225 lb
28
Test results: Single pile Bending moment profiles (jacked pile)
Dense sand (DR=91%) Medium dense sand (DR=59%) Loose sand (DR=38%)
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN 0.3 kN0.4 kN 0.5 kN0.6 kN 0.7 kN0.8 kN 0.9 kN
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN 0.3 kN0.5 kN 0.6 kN0.7 kN 0.9 kN1.0 kN 1.1 kN
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4
Dep
th (m
)
Bending Moment (kN-m)
0.1 kN 0.2 kN0.3 kN 0.4 kN0.5 kN 0.6 kN
1.0 kN-m = 0.738 lb-kips
29
Test results: Single pile Lateral load - deflection curves (preinstalled pile)
0
2
4
6
8
10
12
14
16
18
20
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6Lateral Load (kN)
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Dense sandMedium dense sand
Sand typeQlat, 5%
(kN)Qlat, 10%
(kN)Qlat, 20%
(kN)
Dense 0.35 0.52 0.73
Medium dense 0.22 0.35 0.52
1.0 kN = 225 lb
Test results: Single pile
30
Dense sand (DR=91%) Medium dense sand (DR=59%)
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4Moment (kN-m)
Dep
th (m
)
0.1 kN 0.2 kN0.3 kN 0.4 kN0.5 kN 0.6 kN0.7 kN 0.8 kN
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4Moment (kN-m)
Dep
th (m
)
0.1 kN 0.2 kN0.3 kN 0.4 kN0.5 kN 0.6 kN0.7 kN 0.8 kN
Bending moment profiles (preinstalled pile)
1.0 kN-m = 0.738 lb-kips
31
Test results: Single pile
Sand typeQlat, 5%
(kN)Qlat, 10%
(kN)Qlat, 20%
(kN)
Multi layer 0.28 0.41 0.61
Load-deflection curves and bending moment profiles (Multi-layer soils)
0
2
4
6
8
10
12
14
0.0 0.2 0.4 0.6 0.8 1.0
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Multi layer
Soil TankMedium dense sand
Dense sand
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 0 0.1 0.2 0.3 0.4
Dep
th (m
)
Bending Moment (kN-m)
0.1 kN0.2 kN0.4 kN0.5 kN0.6 kN0.7 kN0.9 kN
32
Effect of pile installation method
Installation Method
Qlat, 10%
(kN)
Jacked 0.71
Driven 0.65
Preinstalled 0.52
Installation Method
Qlat, 10%
(kN)
Jacked 0.42
Driven 0.36
Preinstalled 0.35
Dense sand
Medium dense sandQlat,10% (preinstalled piles) = 84% of Qlat,10% (jacked piles)
Qlat,10% (preinstalled piles) = 73% of Qlat,10% (jacked piles)0
2
4
6
8
10
12
14
16
18
20
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Driven pile (Dense)Jacked pile (Dense)Preinstalled pile (Dense)Driven pile (Medium Dense)Jacked pile (Medium Dense)Preinstalled pile (Medium Dense)
Medium dense
Dense
1.0 kN = 225 lb
33
Comparison of Result with Predictions Comparison of predictions (PYGMY, present analysis) with measurements from model piles driven in dense, medium dense, and loose sand
Dense sand (DR=91%) Medium dense sand (DR=59%) Loose sand (DR=38%)
0
2
4
6
8
10
12
14
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Predicted (PYGMY)
Measured (Driven)
present analysis
0
2
4
6
8
10
12
14
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Predicted (PYGMY)
Measured (Driven)
present analysis
0
2
4
6
8
10
12
14
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Measured
Predicted (PYGMY)present analysis
1.0 kN = 225 lb
34
Comparison of Result with Predictions Comparison of predicted and measured bending moment profiles formodel piles driven in dense sand
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.05 0 0.05 0.1 0.15 0.2
Dep
th (m
)
Bending Moment (kN-m)
Pred_0.1 kNPred_0.2 kNPred_0.3 kNPred_0.4 kNMead_0.1 kNMead_0.2 kNMead_0.3 kNMead_0.4 kN
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0 0.05 0.1 0.15 0.2
Appl
ied
late
ral l
oad
(kN
)
Max. Moment (kN-m)
Predicted
Measured
1.0 kN-m = 0.738 lb-kips
35
Comparison of Results with PYGMY Comparison of predicted and measured bending moment profiles formodel piles driven in dense sand
-0.2
0.0
0.2
0.4
0.6
0.8
1.0
1.2
-0.1 0 0.1 0.2 0.3 0.4
Dep
th (m
)
Bending Moment (kN-m)
Mead_0.2kNMead_0.4kNMead_0.6kNMead_0.8kNMead_1.0kNPred_0.2kNPred_0.4kNPred_0.6kNPred_0.8kNPred_1.0kN
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0.0 0.1 0.2 0.3 0.4 0.5
Appl
ied
Late
ral L
oad
(kN
)
Max. Moment (kN-m)
MeasuredPredicted
1.0 kN-m = 0.738 lb-kips
36
Comparison of Results Comparison of predictions with measurements from model piles driven and preinstalled in dense, medium dense
Dense sand (DR=91%) Medium dense sand (DR=59%)
0
2
4
6
8
10
12
14
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Predicted (PYGMY)Measured (Driven)present analysisMeasured (Preinstalled)
0
2
4
6
8
10
12
14
0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Predicted (PYGMY)Measured (Driven)present analysisMeasured (Preinstalled)
37
Input parameters (present analysis)
Suggested f and g (Lee and Salgado, 2000)
Input parameters for the soil
Critical-state friction angle (deg.) 32.8
Max. void ratio (emax) 0.78
Min. void ratio (emin) 0.47
Coefficient of earth pressure 0.4
Model f-g model
DR(%) f g30 0.98 0.1750 0.97 0.270 0.96 0.2390 0.95 0.26
Input parameters for the model pile
Length (m) 1.2
Diameter / width (m) 0.03
Pile modulus (GPa) 210
38
Input parameters (PYGMY)
PYGMY input parameters for the model pile
Pile property Input value
Length (m) 1.2
Diameter / width (m) 0.03
Bending stiffness of pile, EpIp (kN⋅m2) 3.862
Plastic moment (kN⋅m) 0.5
No. of elements 30
PYGMY input parameters for the soil
Soil property Dense sand Medium dense sand Loose sand
Peak friction angle (deg.) 44 39 36
Initial stiffness gradient (kPa/m) 82,000 34,000 12,000
Effective unit weight (kN/m3) 17.34 16.27 15.64
No. of soil layers 1 1 1
39
p-y curve (PYGMY)
Sand: API criterion (1993)
tanh
: lateral pressure: factor to account for static or cyclic loading
0.9 where equilibrium has been reached under cyclic loading (0.3 - 0.8 / )
uu
k x yp A pA p B
pA
AA x B
⋅ ⋅= ⋅ ⋅ ⋅ ⋅
== ≥ 0.9 for static loading
fultimate bearing pressure at the current depth, gradient of initial modulus of subgrade reaction with depth (kPa/m)lateral displacementdepth below surface pile dia
up xkyxB
=
==== meter
40
p-y curves (PYGMY)
predicted p-y curves (dense sand)
41
ContentsModel pile testing planModel pile testing
Sample preparation Soil tank Sand pluviator
Instrumented model pile Driving system Preinstallation method Jacking system
Installation of piles for pile group testing Lateral loading system
Comparison of test and analysis results Single piles Pile groups
Summary and Conclusions
42
Group piles: Dense sand (DR=90%) Lateral deflection of pile head (4 piles, 3B spacing)
Qlat, 5% = 0.91 kN
Qlat, 10% = 1.59 kN
Qlat, 20% = 2.25 kN
Lateral deflection = 5%, 10%, 20% of the pile diameter
0
2
4
6
8
10
12
14
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Single pile
Pile group
1.0 kN = 225 lb
43
Group piles: Dense sand (DR=90%) Distribution of lateral load
Pile top
4 strain gauges2cm
For lateral load
The difference in the bending momentsdivided by the distance between thestrain gauges is equal to the lateral loadin the pile
0
2
4
6
8
10
12
14
0.0 0.3 0.5 0.8 1.0
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Trailing Pile
Leading Pile
Qh
1.0 kN = 225 lb
44
Group piles: Dense sand (DR=90%) Bending moment of leading and trailing piles
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.5 kN0.9 kN1.3 kN1.6 kN1.9 kN2.2 kN2.5 kN2.9 kN3.2 kN
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.5 kN0.9 kN1.3 kN1.6 kN1.9 kN2.2 kN2.5 kN2.9 kN3.2 kN
Group piles
Leading RowTrailing Row
Qh
Distribution of bending moments of trailing piles
Distribution of bending moments of leading piles
1.0 kN-m = 0.738 lb-kips
45
Group piles: Dense sand (DR=90%) Measured p-multipliers and distribution of lateral load
0.0
0.4
0.8
1.2
1.6
0.0 4.0 8.0 12.0
Late
ral L
oad
(kN
)
Lateral Deflection of Pile Head (mm)
Single pile
Leading pile
Trailing pile
Lateral deflection Leading Pile
Trailing Pile
5 % of B 0.76 0.59 10 % of B 0.74 0.58 20 % of B 0.82 0.63
Measured p-multipliers
1.0 kN = 225 lb
46
Group piles: Medium dense sand (DR=60%) Lateral deflection of pile head (4 piles, 3B spacing)
Qlat, 5% = 0.60 kN
Qlat, 10% = 1.20 kN
Qlat, 20% = 1.56 kN
Lateral deflection = 5%, 10%, 20% of the pile diameter
0
2
4
6
8
10
12
14
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Single pilePile group
1.0 kN = 225 lb
47
Group piles: Medium dense sand (DR=60%) Bending moment of leading and trailing piles
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN0.4 kN0.6 kN0.8 kN1.0 kN1.2 kN1.4 kN1.6 kN2.0 kN
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN0.4 kN0.6 kN0.8 kN1.0 kN1.2 kN1.4 kN1.6 kN2.0 kN
Distribution of bending moments of trailing piles
Distribution of bending moments of leading piles
1.0 kN-m = 0.738 lb-kips
Lateral deflection Leading Pile
Trailing Pile
5 % of B 0.70 0.60
10 % of B 0.68 0.59 20 % of B 0.82 0.71
48
Group piles: Medium dense sand (DR=60%) Measured p-multipliers and distribution of lateral load
0.0
0.4
0.8
1.2
1.6
0.0 4.0 8.0 12.0
Late
ral L
oad
(kN
)
Lateral Deflection of Pile Head (mm)
Single pile
Leading pile
Trailing pile
Measured p-multipliers
1.0 kN = 225 lb
49
Group piles: Loose sand (DR=40%) Lateral deflection of pile head (4 piles, 3B spacing)
Qlat, 5% = 0.47 kN
Qlat, 10% = 0.80 kN
Qlat, 20% = 1.23 kN
Lateral deflection = 5%, 10%, 20% of the pile diameter
0
2
4
6
8
10
12
14
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Single pile
Pile group
1.0 kN = 225 lb
50
Group piles: Loose sand (DR=40%) Bending Moment of leading and trailing piles
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN0.4 kN0.5 kN0.6 kN0.8 kN1.0 kN1.2 kN1.6 kN1.8 kN
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN0.4 kN0.5 kN0.6 kN0.8 kN1.0 kN1.2 kN1.6 kN1.8 kN
Distribution of bending moments of trailing piles
Distribution of bending moments of leading piles
1.0 kN-m = 0.738 lb-kips
Lateral deflection Leading Pile
Trailing Pile
5 % of B 0.68 0.59
10 % of B 0.76 0.65
20 % of B 0.80 0.69
0.0
0.4
0.8
1.2
1.6
0.0 4.0 8.0 12.0
Late
ral L
oad
(kN
)
Lateral Deflection of Pile Head (mm)
Single pile
Leading pile
Trailing pile
51
Group piles: Loose sand (DR=40%) Measured p-multipliers and distribution of lateral load
Measured p-multipliers
52
Group piles: two-layer sand sample Lateral deflection of pile head (4 piles, 3B spacing)
Qlat, 5% = 0.62 kN
Qlat, 10% = 1.21 kN
Qlat, 20% = 1.82 kN
Lateral deflection = 5%, 10%, 20% of the pile diameter
0
2
4
6
8
10
12
14
0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0
Late
ral D
efle
ctio
n of
Pile
Hea
d (m
m)
Lateral Load (kN)
Single
Pile groupSoil Tank
Medium dense sand
Dense sand
1.0 kN = 225 lb
53
Group piles: two-layer sand sample Bending Moment of leading and trailing piles
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN0.4 kN0.6 kN0.8 kN1.2 kN1.4 kN1.6 kN2.0 kN2.4 kN
-0.2
-0.1
0.0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1.0
-0.1 -0.05 0 0.05 0.1 0.15 0.2 0.25 0.3
Dep
th (m
)
Bending Moment (kN-m)
0.2 kN0.4 kN0.6 kN0.8 kN1.2 kN1.4 kN1.6 kN2.0 kN2.4 kN
Distribution of bending moments of trailing piles
Distribution of bending moments of leading piles
1.0 kN-m = 0.738 lb-kips
Lateral deflection Leading Pile
Trailing Pile
5 % of B 0.63 0.49
10 % of B 0.71 0.55
20 % of B 0.84 0.65
0.0
0.4
0.8
1.2
1.6
0.0 4.0 8.0 12.0
Late
ral L
oad
(kN
)
Lateral Deflection of Pile Head (mm)
Single pile
Leading pile
Trailing pile
54
Group piles: two-layer sand sample Measured p-multipliers and distribution of lateral load
Measured p-multipliers
1.0 kN = 225 lb
55
Group piles: p-multipliers
p-multipliers f- p-y relationship for single pile - Reduction in p values for each pile in the group by using f
1
:
1
pn
i ijj
ij
ij
f
i j
β
β
β
== ∏
= = if
Reese et al (2006)
interaction coefficients (pile i and pile j)
56
Group piles: p-multipliers
0.38
0.26
0.34
0.48 1
0.7 1
0.64 1
piLiL
piTiT
piSiT
sB
sB
sB
β
β
β
= ≤
= ≤
= ≤
for a leading pile
for a trailing pile
center-to-center spacing
pile diameter
, , :piL piT piSs s s
for a side-by-side pile
Qh LT
S
S
i
leading offset pile
trailing offset pile
θ
2 2 2 2cos sini iL iSθβ β θ β θ= +
2 2 2 2cos sini iT iSθβ β θ β θ= +
for leading offset pile
for trailing offset pile
:B
57
Group piles: p-multipliers
0.38 0.38
120.090.48 0.48 0.720.03
piLsB
β = = =
4 piles, 3B spacing (=0.09m)
2Qh
4
1
3
1 12 12 13 141
0.623pn
ijj
f β β β β β=
= ∏ = =
for a leading pile
for a side-by-side pile0.34 0.34
130.090.64 0.64 0.920.03
piTsB
β = = =
2 2 2 214 1 1
0.380.38
1
0.340.34
1
2 2 2 214 1 1
cos sin
0.09 20.48 0.48 0.830.03
0.09 20.64 0.64 1.04 10.03
cos sin 0.919
L S
piLL
piLS
L S
sB
sB
β β θ β θ
β
β
β β θ β θ
= +
⋅= = =
⋅= = = →
= + =
for leading offset pile
58
Group piles: p-multipliers
1
2
3
0.64 0.06 1
0.34 0.11 1
0.16 0.14 1
0.04 0.16 1
pL
pT
pT
pT
sf
B
sf
B
sf
B
sf
B
= + ≤
= + ≤
= + ≤
= + ≤
for the leading row
for the 1st trailing row
for the 2nd trailing row
for the 3rd and subsequent trailing row
Mokwa (1999)
59
Group piles: p-multipliers
( )
( )1
0.64 0.06 0.64 0.06 3 0.82
0.34 0.11 0.34 0.11 3 0.67
pL
pT
sf
B
sf
B
= + = + =
= + = + =
for the leading row
for the 1st trailing row
Mokwa (1999)
Leading Pile Trailing Pile
Reese et al (2006) 0.866 0.623
Mokwa (1999) 0.820 0.670
Predicted p-multipliers
60
Group piles: comparison of p-multipliers
0.4
0.6
0.8
1.0
0 5 10 15 20 25 30
p-m
ultip
lier
Lateral Deflection of Pile Head (% of diameter)
Reese et al. (2006)
Mokwa (1999)
Dense
Medium dense
Loose
Leading piles
Comparison of predicted p-multipliers with measurements from pile group tests in dense, medium dense and loose sand
0.4
0.6
0.8
1.0
0 5 10 15 20 25 30
p-m
ultip
lier
Lateral Deflection of Pile Head (% of diameter)
Reese et al. (2006)
Mokwa (1999)
Dense
Medium dense
Loose
61
Group piles: comparison of p-multipliers Comparison of predicted p-multipliers with measurements from pile group tests in dense, medium dense and loose sand
Trailing piles
62
Summary and Conclusions
An instrumented model pile, a soil tank, a large-scale pluviator, a driving system, and a jacking system were fabricated
Lateral load tests were performed on preinstalled, driven and jacked model piles installed in sand prepared at different densities
The effects of soil conditions and pile installation method on the model pile capacities were evaluated
63
Summary and Conclusions
For single piles, the predictions from the developed analysis were in good agreement with the model pile test results for small pile head deflections (up to 10% of the pile diameter)
For pile groups, the measured p-multipliers are in reasonable agreement with those obtained from Mokwa (1999) and Reese et al. (2006)
the measured p-multipliers for the leading piles were 85%~90% less than the predicted values
for the trailing piles, the measured p-multipliers were in good agreement with the predictions
References Basu, D. (2006). Analysis of laterally loaded piles in layered soil. Ph.D. Thesis, Purdue University.Basu, D., Salgado, R. and Prezzi. M. (2008). “Analysis of laterally loaded piles inmultilayered soil deposits.” Final Report FHWA/IN/JTRP-2007/23, JTRPLee, J. & Salgado, R. (2000). Analysis of calibration chamber plate load tests. Can. Geotech. J., 37, 14-25. Mokwa, R. L. (1999). “Investigation of the resistance of pile caps to lateral loading.” Ph.D. Thesis, Virginia Polytechnic Institute and State University. Mokwa, R. L. & Duncan, J. M. (2001). Experimental evaluation of lateral-load resistance of pile caps. J. Geotech. Geoenv. Engng., Am. Soc. Civ. Engrs. 127, No. 2, 185-192. Poulos, H. G. & Davis, E. H. (1980). Pile foundation analysis and design. John Wiley & Sons,Inc. Randolph, M. F. (1981). The response of flexible piles to lateral loading. Geotechnique 31, No. 2,247-259. Reese, L. C., Isenhower, W. M. & Wang, S.-T. (2006). Analysis and design of shallow and deep foundations. John Wiley & Sons, Inc. Reese, L.C. and Van Impe, W.F. (2001). “Single Piles and Pile Groups Under Lateral Loading”, A. A.Balkema, Rotterdam. Salgado, R. (2008). “The Engineering of Foundations”, McGraw-Hill Science.