Design of Piles Under Cyclic Loading

Recent developments in the fields of energy, transport and industrial engineering have led to the emergence of new types of structures and infrastructures subject to variable stresses, for which the usual methods for designing pile foundations are now inadequate. The recommendations presented in this book will help to partly fill this technical gap by proposing a methodological approach and calculation methods to take account of the effects of cyclic loads in the design of foundations on piles. These are based on both laboratory and full scale experiments, and on modeling carried out within the framework of the national SOLCYP project.

Auteur
Alain Puech, Grenoble-Alpes University, France Jacques Garnier, Grenoble-Alpes University, France

Contenu

Foreword xi

Preface xv

List of Symbols xix

Chapter 1 SOLCYP Project 1

1.1 Motivations 1

1.2 The SOLCYP project 2

1.2.1 The ANR-SOLCYP program 3

1.2.2 The national SOLCYP project 4

1.2.3 Organization of the PN-SOLCYP 8

1.3 Content and nature of this book 9

1.4 Regulatory context 10

1.5 Bibliography 11

Chapter 2 Scope and Field of Application of Recommendations 13

2.1 Variable loading and cyclic loading 13

2.2 Structures to which this discussion pertains 14

2.3 Effects of cyclic loading on the foundations 16

2.4 Types of piles 17

2.5 Types of soils 18

2.6 Bibliography 18

Chapter 3 Cyclic Loading 21

3.1 General 21

3.2 Characterization of cyclic loads 22

3.2.1 Regular loading: definitions 22

3.2.2 Cyclic loading of soil samples in the laboratory 23

3.2.3 Real-world cyclic loading 24

3.3 Taking account of real cyclic loading in the design process 24

3.3.1 Principle and definitions 24

3.3.2 Counting methods 27

3.3.3 Damage laws 27

3.4 Bibliography 38

Chapter 4 Introduction to Cyclic Degradation 41

4.1 Introduction 41

4.2 Cyclic degradation of soil properties 41

4.2.1 Recap of the response of soils to monotonic loading 41

4.2.2 Soil response to cyclic loading 42

4.2.3 Contour diagrams 44

4.2.4 Generalized contour diagrams 47

4.2.5 Obtaining contour diagrams for a particular soil 54

4.2.6 Cyclic degradation of the shear modulus 55

4.3 Cyclic degradation of soilpile interfaces 59

4.3.1 General considerations on soilpile interface tests 59

4.3.2 SOLCYP databank on direct shear soilpile tests 66

4.4 Cyclic degradation of pile response 70

4.4.1 Piles subjected to axial cyclic loading 70

4.4.2 Piles subject to lateral cyclic loading 84

4.5 Appendices 91

4.5.1 Appendix 1: Program of CNL and CNS tests and parameters influencing their outcome 91

4.5.2 Appendix 2: CNS tests Corrections to be made to the raw measurements 95

4.6 Bibliography 96

Chapter 5 SOLCYP Design Strategy 101

5.1 General methodology 101

5.2 Knowledge of loads 103

5.3 Analysis of regulatory loads 105

5.4 Criteria of cyclic severity for axial loads 106

5.4.1 Axial capacity of piles: definitions 106

5.4.2 Use of the cyclic stability diagram 107

5.4.3 Influence of soilpile relative stiffness 114

5.5 Cyclic severity criteria for transverse loading 115

5.5.1 Case of sands 115

5.5.2 Case of clays 117

5.6 Detailed characterization of the cyclic loads 119

5.7 Cyclic pile design methods 121

5.8 Obtaining the parameters 122

5.9 Bibliography 122

Chapter 6 Behavior of Piles Subject to Cyclic Axial Loading 125

6.1 Introduction 125

6.2 Large international programs 127

6.3 Tests in clay soils 132

6.3.1 Normally consolidated to slightly overconsolidated clays 132

6.3.2 Highly overconsolidated clays 137

6.3.3 Comparisons of the results 144

6.4 Tests in sands 146

6.4.1 Silica sand 146

6.4.2 Carbonate soils 158

6.5 About the static load-bearing capacity 160

6.5.1 Ageing in sands 160

6.5.2 Effect of time and preshearing in clays 161

6.5.3 Softening 162

6.5.4 Loading rate 162

6.6 Summary 163

6.7 Appendix: cyclic loading tests on piles at the Merville site 165

6.7.1 Introduction 165

6.7.2 Results obtained on two driven piles (B1 and B4) 166

6.7.3 Results obtained on bored (CFA) piles 167 6.7.4 Results obtained on bored screw piles 169</p&gt...