Design Of Pile Foundations In Liquefiable Soils

by Gopal Madabhushi, Stuart Haigh, Jonathan Knappett

Overview

Pile foundations are the most common form of deep foundations that are used both onshore and offshore to transfer large superstructural loads into competent soil strata. This book provides many case histories of failure of pile foundations due to earthquake loading and soil liquefaction. Based on the observed case histories, the possible mechanisms of failure of the pile foundations are postulated. The book also deals with the additional loading attracted by piles in liquefiable soils due to lateral spreading of sloping ground. Recent research at Cambridge forms the backbone of this book with the design methodologies being developed directly based on quantified centrifuge test results and numerical analysis.The book provides designers and practicing civil engineers with a sound knowledge of pile behaviour in liquefiable soils and easy-to-use methods to design pile foundations in seismic regions. For graduate students and researchers, it brings together the latest research findings on pile foundations in a way that is relevant to geotechnical practice.

Product Details

ISBN-13:	9781848163621
Publisher:	Imperial College Press
Publication date:	09/18/2009
Pages:	232
Product dimensions:	6.10(w) x 9.00(h) x 0.80(d)

Table of Contents

Foreword vii

Preface ix

1 Performance of Pile Foundations 1

1.1 Introduction 1

1.1.1 Axial capacity of a single pile 3

1.1.2 Pile capacity based on CPT testing 5

1.1.2.1 Pile base capacity 6

1.1.2.2 Shaft friction 7

1.2 Performance of Pile Foundations During Earthquake Loading 8

1.3 Soil Liquefaction and Lateral Spreading 11

1.4 Performance of Pile Foundations in Past Earthquakes 12

1.4.1 Showa bridge failure 14

1.4.2 Niigata Family Court House building 18

1.4.3 The Landing Bridge performance 21

1.4.4 The Harbour Master's Tower at Kandla Port 27

1.5 Modes of Pile Failure in Liquefiable Soils 31

1.5.1 Failure mechanisms for single piles 31

1.5.2 Failure mechanisms for pile groups 35

1.6 Summary 38

2 Inertial and Kinematic Loading 39

2.1 Pile Behaviour Under Earthquake Loading 39

2.1.1 Inertial loading 39

2.1.2 Kinematic loading in level ground 41

2.1.3 Kinematic loading in sloping ground 43

2.2 Analysis of Laterally Loaded Piles Under Static Conditions 43

2.2.1 Simplified soil profiles 44

2.2.2 Simplified analysis procedures for piles under static loading 46

Analysis of Laterally Loaded Piles Under Earthquake Loading 48

2.3.1 Variation in the action of inertial and kinematic loads with depth 48

2.3.2 Effective lengths of piles 49

2.3.3 Pile flexibility 50

2.4 Kinematic Response in Level Ground 51

2.5 Kinematic Loading in Laterally Spreading Soil 54

2.6 Inertial Response 56

2.6.1 Relative stiffness of pile-soil system 56

2.6.2 Damping coefficients 57

2.7 p-y Analysis of Piles 58

2.7.1 Static lateral loading 58

2.7.2 Cyclic lateral loading 62

2.7.3 p-y analysis under earthquake loading - level ground63

2.7.4 p-y analysis under earthquake loading - sloping ground 64

2.8 Limit Equilibrium Analysis of Piles Subjected to Earthquake Loading 67

2.8.1 Limit equilibrium of piles in laterally spreading soils 68

2.8.2 Limit equilibrium analysis in the presence of nonliquefied crust 70

2.8.2.1 Stiff clay as a nonliquefiable layer 70

2.8.2.2 Dense sand as a nonliquefiable layer 74

2.9 Provisions in Eurocode 8 76

2.9.1 Combination rules 77

2.9.2 Pile head fixity coefficients 77

2.9.3 Kinematic loading 78

2.10 Summary 79

3 Accounting for Axial Loading in Level Ground 80

3.1 Liquefaction as a Foundation Hazard 80

3.1.1 Liquefaction 80

3.1.2 Determination of liquefaction susceptibility 82

3.2 Influence of Axial Loading on Pile Failure 84

3.3 Axial Load Transfer Due to Liquefaction 85

3.3.1 Liquefaction-induced (co-seismic) 85

3.3.2 Downdrag (post-earthquake) 88

3.4 Pile Settlement 88

3.4.1 Liquefaction-induced (co-seismic) 88

3.4.2 Downdrag (post-earthquake) 92

3.5 Guidelines for Designing Against Bearing Failure 95

3.6 Instability of Single Piles and Pile Groups 98

3.6.1 Rock-socketed piles 98

3.6.2 Floating piles 105

3.7 Bearing vs. Buckling Failure 108

3.7.1 Methodology 108

3.7.2 Sample analysis 110

3.7.3 Ultimate axial limiting states for piled foundations 111

3.7.4 Use of limiting states in pile sizing 114

3.8 Summary 115

4 Lateral Spreading of Sloping Ground 116

4.1 Liquefaction-induced Lateral Spreading 116

4.1.1 Introduction 116

4.2 Simple Methods to Estimate the Extent of Lateral Spreading 120

4.3 Effects of Lateral Spreading on Pile Foundations 124

4.3.1 Presence of nonliquefiable crust 125

4.3.2 Lateral pressures generated on piles and pile caps 126

4.3.3 Current codal provisions 134

4.3.3.1 Specifications for Highway Bridges (JRA, 2002) 134

4.3.3.2 Design Standard for Railway Facilities (RTRI 1999) 134

4.3.3.3 Recommendations for Design of Building Foundations (AIJ 2001) 135

4.3.4 Recent experimental data vs codal provisions 135

4.4 Recommendations on Estimation of Lateral Loads for Pile Design 136

5 Axial Loading on Piles in Laterally Spreading Ground 138

5.1 Introduction 138

5.2 Phasing of Loads 138

5.2.1 Inertial and kinematic loads 139

5.2.2 Presence of axial loads 142

5.3 Peak Lateral Response of Piled Foundations 143

5.4 Residual Lateral Response of Piled Foundations 147

5.4.1 Single piles 147

5.4.2 Pile groups (including axial load) 149

5.4.3 Comparison of single pile and group pile behaviour 154

5.4.4 Insight into effects of axial load on group response 155

5.5 Validation of Effects of Axial Pile Load 157

5.6 Recommendations for Designing Piles in Laterally Spreading Ground 160

6 Design Examples 165

6.1 Introduction 165

6.2 Design of Piles Under Static Loading 165

6.2.1 Example 1: Preliminary design of piles under static loading 166

6.2.1.1 End bearing 166

6.2.1.2 Shaft resistance 167

6.2.2 Example 2: Preliminary design of piles using CPT data 168

6.2.2.1 End bearing 168

6.2.2.2 Shaft resistance 168

6.3 Inertial and Kinematic Loading on Piles in Level Ground 171

6.3.1 Example 3: Soil stiffness and natural frequency 172

6.3.2 Example 4: Effective length and flexibility of the pile 175

6.3.2.1 Effective length of the pile 175

6.3.2.2 Flexibility of the pile 176

6.3.3 Example 5: Inertial loading on the pile 177

6.3.4 Example 6: Kinematic interaction 180

6.4 Design of Piles in Level Liquefiable Ground 182

6.4.1 Example 7: Determination of liquefaction potential from CPTdata 182

6.4.2 Example 8: Pile sizing based on liquefaction considerations 187

6.4.3 Example 9: Inertial response in level liquefied ground 191

6.5 Design of Piles in Sloping Liquefiable Ground 192

6.5.1 Example 10: Pile group in two-layer soil profile subject to lateral spreading 192

6.5.1.1 Method 1 196

6.5.1.2 Method 2 196

6.5.1.3 Method 3 196

6.5.2 Example 11: Pile group in three-layer soil profile subject to lateral spreading 199

6.6 Summary of Inclusive Design Procedure 200

References 203

Index 211