Implementation of Laterally Loaded Piles in Multi-Layer Soils

Implementation of Laterally Loaded Piles in Multi-Layer Soils JTRP SPR- 3261 Final SAC meeting SAC members Mir Zaheer and Keith Hoernschemeyer Purdue University

Introduction Analysis developed for the design of laterally loaded piles in multi-layer soil using energy principles (SPR 2630) Analysis validation for piles in sand Model pile lateral load tests (single piles and pile groups) Driven Preinstalled Jacked 1

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 2

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 3

Contents Model pile testing plan Model 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 4

Model pile testing plan Model Pile Test Laterally Loaded Piles Single piles Pile groups Driven Preinstalled Jacked Driven (4 piles) 5

Model pile testing plan Pile Installation Soil Condition Relative Density Dense sand D R 90% Driven Medium dense sand D R 60% Loose sand D R 40% Single pile Group piles Preinstalled Jacked Driven Multi-layer D R 60%, 90 % Dense sand D R 90% Medium dense sand D R 60% Dense sand D R 90% Medium dense sand D R 60% Loose sand D R 40% Dense sand D R 90% Medium dense sand D R 60% Loose sand D R 40% Multi-layer D R 60%, 90 % 6

Contents Model pile testing plan Model 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 7

Soil tank Soil tank (D=2m, H=1.6m) Hammer Guide arm for pile driving (rotatable and extensible) Guide rod Reaction beam support Model pile 8

Soil tank Guide arm for pile driving Reaction beam (detachable) Open Holes for draining sand Close 9

Sand pluviator Large-scale sand pluviation system (D=2m) Gantry Hoist for adjusting height Diffuser sieves Shutter plate Soil tank 10

Sand pluviator Top of pluviator Two sieve layers Holes for sand pluviation 11

Sand pluviator Schematic view and photo of sand pluviator Chains Hoist Shutter plate Sand supply Falling sand jets Raining sand Diffuser sieves Deposited sand 12

Sample preparation Top view of pluviator Sand pluviation 13

Draining sand Draining sand after the test 14

Contents Model pile testing plan Model 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 15

Instrumented model pile Smooth steel pipe (D=3cm, L=120cm, t=0.2cm) Collected wires at pile head Closed-ended pile base 16

Instrumented model pile 22 strain gauges Closer near the base (higher load transfer rate) Load cell-shaped pile base 17

Driving System Installation of driven pile Hammer Guide Rod Pile Cap Filled soil tank 18

Preinstallation of model pile Preinstalled pile

Pile jacking system 20

Pile jacking system Max. rate = 5 cm/min Screw Rod Model Pile Motor 21

Installation of Group piles Setup Pile driving guide (Wooden Box Frame) Pile driving order 3 2 4 Piles & Steel Cap 4 1 22

Lateral loading system Pile groups Single pile 23

Contents Model pile testing plan Model 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 24

Test results: Single pile Lateral load - deflection curves (driven pile) Lateral Deflection of Pile Head (mm) 0 2 4 6 8 10 12 14 16 Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 1.0 kn = 225 lb Dense sand Medium dense sand Loose sand Ultimate lateral loads Sand type Q lat,5%, Q lat,10% Q lat,20% corresponding to lateral pile head deflections of 5, 10 and 20 % of the pile diameter Q lat, 5% (kn) Q lat, 10% (kn) Q lat, 20% (kn) Dense 0.42 0.65 0.92 Medium dense 0.24 0.36 0.54 Loose 0.19 0.29 0.44 25

Test results: Single pile Bending moment profiles (driven pile) 1.0 kn-m = 0.738 lb-kips Dense sand (D R =91%) Medium dense sand (D R =59%) Loose sand (D R =38%) Depth (m) -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Bending Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4 M 0.1 kn 0.2 kn 0.3 kn 0.4 kn 0.5 kn 0.6 kn 0.7 kn 0.8 kn 0.9 kn 1.0 kn 1.1 kn 1.2 kn Bending moment EI ( εt εc) = h Rollins et al. (1998) Depth (m) -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 ε Bending Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4 0.1 kn 0.2 kn 0.3 kn 0.4 kn 0.5 kn 0.6 kn 0.7 kn 0.8 kn 0.9 kn T : tensile strain ε c : compressive strain h: horizontal distance between gauges EI: bending stiffness of pile Depth (m) -0.1 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 Bending Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4 0.1 kn 0.2 kn 0.3 kn 0.4 kn 0.5 kn 0.6 kn 26

Test results: Single pile Lateral load - deflection curves (jacked pile) 0 Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 Lateral Deflection of Pile Head (mm) 2 4 6 8 10 12 14 Dense sand Medium dense sand Loose sand Sand type Q lat, 5% (kn) Q lat, 10% (kn) Q lat, 20% (kn) Dense 0.51 0.71 0.97 Medium dense 0.32 0.42 0.59 Loose 0.21 0.31 0.47 1.0 kn = 225 lb 27

Test results: Single pile Bending moment profiles (jacked pile) Dense sand (D R =91%) Medium dense sand (D R =59%) Loose sand (D R =38%) Bending Moment (kn-m) Bending Moment (kn-m) Bending Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4-0.1-0.1 0 0.1 0.2 0.3 0.4-0.1-0.1 0 0.1 0.2 0.3 0.4-0.1 0.0 0.0 0.0 0.1 0.1 0.1 0.2 0.2 0.2 0.3 0.3 0.3 Depth (m) 0.4 0.5 0.6 Depth (m) 0.4 0.5 0.6 Depth (m) 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.2 kn 0.3 kn 0.5 kn 0.6 kn 0.7 kn 0.9 kn 1.0 kn 1.1 kn 0.7 0.8 0.9 1.0 0.2 kn 0.3 kn 0.4 kn 0.5 kn 0.6 kn 0.7 kn 0.8 kn 0.9 kn 0.7 0.8 0.9 1.0 0.1 kn 0.2 kn 0.3 kn 0.4 kn 0.5 kn 0.6 kn 1.0 kn-m = 0.738 lb-kips 28

Test results: Single pile Lateral load - deflection curves (preinstalled pile) 0 Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 1.6 Lateral Deflection of Pile Head (mm) 2 4 6 8 10 12 14 16 18 20 Dense sand Medium dense sand Sand type Q lat, 5% (kn) Q lat, 10% (kn) Q lat, 20% (kn) Dense 0.35 0.52 0.73 Medium dense 0.22 0.35 0.52 1.0 kn = 225 lb 29

Test results: Single pile Bending moment profiles (preinstalled pile) Dense sand (D R =91%) Medium dense sand (D R =59%) -0.1 Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4-0.1 Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4 0.0 0.0 0.1 0.1 0.2 0.2 Depth (m) 0.3 0.4 0.5 0.6 Depth (m) 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.1 kn 0.2 kn 0.3 kn 0.4 kn 0.5 kn 0.6 kn 0.7 kn 0.8 kn 0.7 0.8 0.9 1.0 0.1 kn 0.2 kn 0.3 kn 0.4 kn 0.5 kn 0.6 kn 0.7 kn 0.8 kn 1.0 kn-m = 0.738 lb-kips 30

Test results: Single pile Load-deflection curves and bending moment profiles (Multi-layer soils) 0 Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0-0.1 Bending Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4 Lateral Deflection of Pile Head (mm) 2 4 6 8 10 12 14 Multi layer Depth (m) 0.0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.1 kn 0.2 kn 0.4 kn 0.5 kn 0.6 kn 0.7 kn 0.9 kn Sand type Q lat, 5% (kn) Q lat, 10% (kn) Q lat, 20% (kn) Medium dense sand Soil Tank Multi layer 0.28 0.41 0.61 Dense sand 31

Effect of pile installation method Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 Dense sand Q lat,10% (preinstalled piles) = 73% of Q lat,10% (jacked piles) Lateral Deflection of Pile Head (mm) 2 4 6 8 10 12 14 16 18 20 Medium dense Driven pile (Dense) Jacked pile (Dense) Preinstalled pile (Dense) Driven pile (Medium Dense) Jacked pile (Medium Dense) Preinstalled pile (Medium Dense) Dense Installation Method Q lat, 10% (kn) Jacked 0.71 Driven 0.65 Preinstalled 0.52 Medium dense sand Q lat,10% (preinstalled piles) = 84% of Q lat,10% (jacked piles) Installation Method Q lat, 10% (kn) Jacked 0.42 Driven 0.36 1.0 kn = 225 lb Preinstalled 0.35 32

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 (D R =91%) Medium dense sand (D R =59%) Loose sand (D R =38%) Lateral Deflection of Pile Head (mm) Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 2 4 6 8 10 12 14 Predicted (PYGMY) Measured (Driven) present analysis Lateral Deflection of Pile Head (mm) Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 Predicted (PYGMY) 2 Measured (Driven) 4 6 8 10 12 14 present analysis Lateral Deflection of Pile Head (mm) Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 0 2 4 6 8 10 12 14 Measured Predicted (PYGMY) present analysis 1.0 kn = 225 lb 33

Comparison of Result with Predictions Comparison of predicted and measured bending moment profiles for model piles driven in dense sand Bending Moment (kn-m) 0.8-0.1-0.05 0 0.05 0.1 0.15 0.2 0.7 Depth (m) 0.0 0.1 0.2 0.3 0.4 0.5 Applied lateral load (kn) 0.6 0.5 0.4 0.3 Predicted Measured 0.6 0.7 0.8 0.9 1.0 Pred_0.1 kn Pred_0.2 kn Pred_0.3 kn Pred_0.4 kn Mead_0.1 kn Mead_0.2 kn Mead_0.3 kn Mead_0.4 kn 0.2 0.1 0.0 0 0.05 0.1 0.15 0.2 Max. Moment (kn-m) 1.0 kn-m = 0.738 lb-kips 34

Comparison of Results with PYGMY Comparison of predicted and measured bending moment profiles for model piles driven in dense sand -0.2 Bending Moment (kn-m) -0.1 0 0.1 0.2 0.3 0.4 1.4 1.2 Depth (m) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 Mead_0.2kN Mead_0.4kN Mead_0.6kN Mead_0.8kN Mead_1.0kN Pred_0.2kN Pred_0.4kN Pred_0.6kN Pred_0.8kN Pred_1.0kN Applied Lateral Load (kn) 1.0 0.8 0.6 0.4 0.2 0.0 Measured Predicted 0.0 0.1 0.2 0.3 0.4 0.5 Max. Moment (kn-m) 1.0 kn-m = 0.738 lb-kips 35

Comparison of Results Comparison of predictions with measurements from model piles driven and preinstalled in dense, medium dense Dense sand (D R =91%) Medium dense sand (D R =59%) Lateral Deflection of Pile Head (mm) 0 2 4 6 8 10 12 14 Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Predicted (PYGMY) Measured (Driven) present analysis Measured (Preinstalled) Lateral Deflection of Pile Head (mm) 0 2 4 6 8 10 12 14 Lateral Load (kn) 0.0 0.2 0.4 0.6 0.8 1.0 1.2 1.4 Predicted (PYGMY) Measured (Driven) present analysis Measured (Preinstalled) 36

Input parameters (present analysis) Input parameters for the model pile Length (m) 1.2 Diameter / width (m) 0.03 Pile modulus (GPa) 210 Input parameters for the soil Critical-state friction angle (deg.) 32.8 Max. void ratio (e max ) 0.78 Min. void ratio (e min ) 0.47 Coefficient of earth pressure 0.4 Model f-g model Suggested f and g (Lee and Salgado, 2000) D R (%) f g 30 0.98 0.17 50 0.97 0.2 70 0.96 0.23 90 0.95 0.26 37

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, E p I p (kn m 2 ) 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/m 3 ) 17.34 16.27 15.64 No. of soil layers 1 1 1 38

p-y curve (PYGMY) Sand: API criterion (1993) p k x y = A pu tanh A pu B p : lateral pressure A: factor to account for static or cyclic loading A = 0.9 where equilibrium has been reached under cyclic loading A= (0.3-0.8 x/ B) 0.9 for static loading pu = fultimate bearing pressure at the current depth, x k = gradient of initial modulus of subgrade reaction with depth (kpa/m) y = lateral displacement x = depth below surface B = pile diameter 39

p-y curves (PYGMY) predicted p-y curves (dense sand) 40

Contents Model pile testing plan Model 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 41

Group piles: Dense sand (D R =90%) Lateral deflection of pile head (4 piles, 3B spacing) Lateral Deflection of Pile Head (mm) 0 2 4 6 8 10 12 14 Lateral Load (kn) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Single pile Pile group 1.0 kn = 225 lb Lateral deflection = 5%, 10%, 20% of the pile diameter Q lat, 5% = 0.91 kn Q lat, 10% = 1.59 kn Q lat, 20% = 2.25 kn 42

Group piles: Dense sand (D R =90%) Distribution of lateral load Lateral Deflection of Pile Head (mm) Lateral Load (kn) 0.0 0.3 0.5 0.8 1.0 0 2 4 6 8 10 12 Trailing Pile Leading Pile 14 1.0 kn = 225 lb Q h 2cm For lateral load Pile top 4 strain gauges The difference in the bending moments divided by the distance between the strain gauges is equal to the lateral load in the pile 43

Group piles: Dense sand (D R =90%) Bending moment of leading and trailing piles -0.2-0.1 Distribution of bending moments of trailing piles 0.0 0.1 Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 Distribution of bending moments of leading piles -0.2-0.1 0.0 0.1 Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 Group piles 0.2 0.2 Depth (m) 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.5 kn 0.9 kn 1.3 kn 1.6 kn 1.9 kn 2.2 kn 2.5 kn 2.9 kn 3.2 kn Depth (m) 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.5 kn 0.9 kn 1.3 kn 1.6 kn 1.9 kn 2.2 kn 2.5 kn 2.9 kn 3.2 kn Q h Trailing Row Leading Row 1.0 kn-m = 0.738 lb-kips 44

Group piles: Dense sand (D R =90%) Measured p-multipliers and distribution of lateral load 1.6 Single pile Lateral Load (kn) 1.2 0.8 Leading pile Trailing pile Measured p-multipliers 0.4 Lateral deflection Leading Pile Trailing Pile 5 % of B 0.76 0.59 0.0 0.0 4.0 8.0 12.0 Lateral Deflection of Pile Head (mm) 10 % of B 0.74 0.58 20 % of B 0.82 0.63 1.0 kn = 225 lb 45

Group piles: Medium dense sand (D R =60%) Lateral deflection of pile head (4 piles, 3B spacing) 0 Lateral Load (kn) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Single pile Lateral Deflection of Pile Head (mm) 2 4 6 8 10 12 14 1.0 kn = 225 lb Pile group Lateral deflection = 5%, 10%, 20% of the pile diameter Q lat, 5% = 0.60 kn Q lat, 10% = 1.20 kn Q lat, 20% = 1.56 kn 46

Group piles: Medium dense sand (D R =60%) Bending moment of leading and trailing piles Depth (m) -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 Distribution of bending moments of trailing piles Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.2 kn 0.4 kn 0.6 kn 0.8 kn 1.0 kn 1.2 kn 1.4 kn 1.6 kn 2.0 kn Depth (m) Distribution of bending moments of leading 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 Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.2 kn 0.4 kn 0.6 kn 0.8 kn 1.0 kn 1.2 kn 1.4 kn 1.6 kn 2.0 kn 1.0 kn-m = 0.738 lb-kips 47

Group piles: Medium dense sand (D R =60%) Measured p-multipliers and distribution of lateral load 1.6 Single pile Lateral Load (kn) 1.2 0.8 Leading pile Trailing pile Measured p-multipliers 0.4 0.0 0.0 4.0 8.0 12.0 Lateral Deflection of Pile Head (mm) 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 1.0 kn = 225 lb 48

Group piles: Loose sand (D R =40%) Lateral deflection of pile head (4 piles, 3B spacing) 0 Lateral Load (kn) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Single pile Lateral Deflection of Pile Head (mm) 2 4 6 8 10 12 14 1.0 kn = 225 lb Pile group Lateral deflection = 5%, 10%, 20% of the pile diameter Q lat, 5% = 0.47 kn Q lat, 10% = 0.80 kn Q lat, 20% = 1.23 kn 49

Group piles: Loose sand (D R =40%) Bending Moment of leading and trailing piles Distribution of bending moments of trailing piles Distribution of bending moments of leading piles Depth (m) -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 Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.2 kn 0.4 kn 0.5 kn 0.6 kn 0.8 kn 1.0 kn 1.2 kn 1.6 kn 1.8 kn Depth (m) -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 Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 0.2 kn 0.4 kn 0.5 kn 0.6 kn 0.8 kn 1.0 kn 1.2 kn 1.6 kn 1.8 kn 1.0 kn-m = 0.738 lb-kips 50

Group piles: Loose sand (D R =40%) Measured p-multipliers and distribution of lateral load 1.6 Single pile Lateral Load (kn) 1.2 0.8 Leading pile Trailing pile Measured p-multipliers 0.4 0.0 0.0 4.0 8.0 12.0 Lateral Deflection of Pile Head (mm) 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 51

Group piles: two-layer sand sample Lateral deflection of pile head (4 piles, 3B spacing) Lateral Deflection of Pile Head (mm) 0 2 4 6 8 10 12 14 Lateral Load (kn) 0.0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Single Pile group 1.0 kn = 225 lb Medium dense sand Dense sand Lateral deflection = 5%, 10%, 20% of the pile diameter Q lat, 5% = 0.62 kn Q lat, 10% = 1.21 kn Q lat, 20% = 1.82 kn Soil Tank 52

Group piles: two-layer sand sample Bending Moment of leading and trailing piles -0.2-0.1 0.0 0.1 0.2 Distribution of bending moments of trailing piles Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3-0.2-0.1 0.0 0.1 0.2 Distribution of bending moments of leading piles Bending Moment (kn-m) -0.1-0.05 0 0.05 0.1 0.15 0.2 0.25 0.3 Depth (m) 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.2 kn 0.4 kn 0.6 kn 0.8 kn 1.2 kn 1.4 kn 1.6 kn 2.0 kn 2.4 kn Depth (m) 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.0 0.2 kn 0.4 kn 0.6 kn 0.8 kn 1.2 kn 1.4 kn 1.6 kn 2.0 kn 2.4 kn 1.0 kn-m = 0.738 lb-kips 53

Group piles: two-layer sand sample Measured p-multipliers and distribution of lateral load 1.6 Single pile Lateral Load (kn) 1.2 0.8 Leading pile Trailing pile Measured p-multipliers 0.4 0.0 0.0 4.0 8.0 12.0 Lateral Deflection of Pile Head (mm) 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 1.0 kn = 225 lb 54

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 Reese et al (2006) f i β β ij ij : n p = β j= 1 ij interaction coefficients (pile i and pile j) = 1 if i = j 55

Group piles: p-multipliers leading offset pile S trailing offset pile Q h T i θ L spil, spit, spis : S center-to-center spacing B : pile diameter β β β il it it 0.38 spil = 0.48 1 B 0.26 spit = 0.7 1 B 0.34 spis = 0.64 1 B for a leading pile for a trailing pile for a side-by-side pile β = β cos θ + β sin θ 2 2 2 2 iθ il is for leading offset pile β = β cos θ + β sin θ 2 2 2 2 iθ it is for trailing offset pile 56

Group piles: p-multipliers for a leading pile β 12 s pil 0.38 0.38 0.09 = 0.48 = 0.48 = 0.72 B 0.03 for a side-by-side pile β 13 s pit 0.34 0.34 0.09 = 0.64 = 0.64 = 0.92 B 0.03 for leading offset pile 1 2 Q h 3 4 4 piles, 3B spacing (=0.09m) β = β cos θ + β sin θ β β 2 2 2 2 14 1L 1S 1L 1S 0.38 0.34 2 2 2 2 14 1L 1S 0.38 spil 0.09 2 = 0.48 = 0.48 = 0.83 B 0.03 0.34 spil 0.09 2 = 0.64 = 0.64 = 1.04 1 B 0.03 β = β cos θ + β sin θ = 0.919 n p f = β = β β β β = 1 ij 12 12 13 14 j= 1 0.623 57

Group piles: p-multipliers Mokwa (1999) f f f f L T1 T 2 T 3 sp = 0.64 + 0.06 1 B sp = 0.34 + 0.11 1 B sp = 0.16 + 0.14 1 B sp = 0.04 + 0.16 1 B for the leading row for the 1st trailing row for the 2nd trailing row for the 3rd and subsequent trailing row 58

Group piles: p-multipliers Mokwa (1999) f f L T1 sp = 0.64 + 0.06 = 0.64 + 0.06( 3) = 0.82 B sp = 0.34 + 0.11 = 0.34 + 0.11( 3) = 0.67 B for the leading row for the 1st trailing row Predicted p-multipliers Leading Pile Trailing Pile Reese et al (2006) 0.866 0.623 Mokwa (1999) 0.820 0.670 59

Group piles: comparison of p-multipliers Comparison of predicted p-multipliers with measurements from pile group tests in dense, medium dense and loose sand 1.0 0.8 p-multiplier 0.6 Reese et al. (2006) Mokwa (1999) Leading piles Dense Medium dense Loose 0.4 0 5 10 15 20 25 30 Lateral Deflection of Pile Head (% of diameter) 60

Group piles: comparison of p-multipliers Comparison of predicted p-multipliers with measurements from pile group tests in dense, medium dense and loose sand 1.0 0.8 Reese et al. (2006) Mokwa (1999) Dense Medium dense Loose p-multiplier 0.6 Trailing piles 0.4 0 5 10 15 20 25 30 Lateral Deflection of Pile Head (% of diameter) 61

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 62

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 63

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