Design of Piles Under Cyclic Loading: SOLCYP Recommendations

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.

Table of Contents:
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 soil–pile interfaces 59 4.3.1 General considerations on soil–pile interface tests 59 4.3.2 SOLCYP databank on direct shear soil–pile 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 soil–pile 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 6.8 Bibliography  170 Chapter 7 Design of Piles Subjected to Cyclic Axial Loading  177 7.1 Introduction  177 7.2 General principles 178 7.3 The NGI approach 180 7.3.1 Fundamental principles  180 7.3.2 PAXCY and PAX2 programs 182 7.4 The ICL approach 184 7.4.1 Basic principle  184 7.4.2 The ABC global method  185 7.4.3 Local applications of the ABC method  188 7.5 The RATZ-CYCLOPS suite of programs 188 7.6 The SCARP program 191 7.6.1 Description of the SCARP program 191 7.6.2 Calibration of the SCARP program 195 7.7 Finite Element Method approaches 201 7.8 The SOLCYP approach for non-cohesive soils  203 7.8.1 General principles 203 7.8.2 Choice of parameters to characterize the soil–pile system 204 7.8.3 Modeling of the results of direct soil–structure shear 207 7.8.4 Modeling by the t–z envelope curve method 208 7.8.5 Modeling by the method of t–z cyclic curves (TZC software)  211 7.8.6 FEM modeling  217 7.8.7 Case of driven piles  224 7.9 Bibliography  225 Chapter 8 Behavior of Piles Subject to Cyclic Lateral Loading 233 8.1 Soil–pile interaction under lateral loading 233 8.1.1 Relative stiffness 234 8.1.2 Concept of lateral reaction 236 8.1.3 Crucial role of surface layers 236 8.2 Main experimental data  238 8.3 Available data on the effect of the cycles 240 8.3.1 Effect of cycles on the pile’s lateral displacement 240 8.3.2 Effect of cycles on the maximum bending moment in the pile 252 8.3.3 Effect of cycles on the P–y reaction curves  256 8.4 Contribution of the SOLCYP project  259 8.4.1 Context and scope of the studies conducted 259 8.4.2 Testing conditions  260 8.5 Data obtained on the effect of cycles 263 8.5.1 Case of sands 264 8.5.2 Case of clays 271 8.6 Final overview of the data on the effect of cycles 285 8.6.1 Effects on pile head displacement  286 8.6.2 Effects on the maximum moment and the reactions in the soil 291 8.7 Bibliography  292 Chapter 9 Design of Piles Subject to Cyclic Lateral Loading  299 9.1 Recap of the current rules 300 9.2 Methodology to take account of cyclic loads 303 9.3 Taking account of the cycles by the global method SOLCYP-G  305 9.3.1 Principles of the global method 305 9.3.2 Conventional limit load and failure load 305 9.3.3 Degree of relative stiffness of the pile and limits of flexible and rigid piles 308 9.3.4 Presizing of the pile subject to the maximum static load Hmax  311 9.3.5 Cyclic severity criteria  314 9.3.6 Effect of cycles on the pile head displacement 315 9.3.7 Effect of cycles on the maximum bending moment  319 9.4 Taking account of cycles by a local method SOLCYP-L 319 9.4.1 Principle of the local method 319 9.4.2 Determination of the P-multipliers for monotonic P–y curves  320 9.5 Domains of validity and example of application 323 9.5.1 Domains of validity of the global method SOLCYP-G and local method SOLCYP-L 323 9.5.2 Example of application of the global and local methods 327 9.6 Conclusion  345 9.7 Bibliography  345 Chapter 10 Determination of Cyclic Parameters for Pile Design 347 10.1 Introduction  347 10.2 Parameters for the design of piles subjected to cyclic loads 348 10.2.1 Mineralogy  350 10.2.2 Parameters for monotonic calculations 351 10.2.3 Cyclic parameters  352 10.2.4 Consolidation parameters 352 10.2.5 Remolding parameters  353 10.3 Obtaining the parameters for the design of piles subjected to cyclic loading 353 10.3.1 Lab tests 353 10.3.2 In situ tests  365 10.4 Bibliography 370 Chapter 11 Recommendations for Testing Piles Under Cyclic Loading 377 11.1 Introduction  377 11.2 Reasons for the tests 378 11.3 The different test methods  379 11.4 Contribution of calibration chamber tests: Axial loading 381 11.5 Contribution of centrifuge tests: Axial or transverse loading  383 11.6 In situ axial loading tests  384 11.6.1 Objectives of the test  384 11.6.2 Design support tests (FEED tests) 385 11.6.3 Validation tests (Non-Working Pile Tests) 391 11.6.4 Control tests (Working Pile Tests) 393 11.7 Transverse loading tests in situ  394 11.7.1 Objectives and representativity of tests 394 11.7.2 Design support tests (FEED tests) 395 11.7.3 Validation tests (Non-Working Pile Tests) 399 11.7.4 Control tests (Working Pile Tests) 400 11.8 Appendix 1: Recap on scaling effects 401 11.8.1 Tests on reduced-scale models in the lab  402 11.8.2 Tests of piles in situ 404 11.9 Appendix 2: In situ axial loading 404 11.9.1 Test setup 404 11.9.2 Instrumentation and data acquisition 406 11.10 Appendix 3: Transverse loading in situ 409 11.10.1 Test setup  409 11.10.2 Instrumentation and data acquisition  411 11.11 Bibliography 413 Index 417