Soil Dynamics and Foundation Modeling

Junbo Jia

Soil Dynamicsand Foundation ModelingOffshore and Earthquake Engineering

123

Junbo JiaAker SolutionsBergenNorway

ISBN 978-3-319-40357-1 ISBN 978-3-319-40358-8 (eBook)https://doi.org/10.1007/978-3-319-40358-8

Library of Congress Control Number: 2017956333

© Springer International Publishing AG 2018This work is subject to copyright. All rights are reserved by the Publisher, whether the whole or partof the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations,recitation, broadcasting, reproduction on microfilms or in any other physical way, and transmissionor information storage and retrieval, electronic adaptation, computer software, or by similar or dissimilarmethodology now known or hereafter developed.The use of general descriptive names, registered names, trademarks, service marks, etc. in thispublication does not imply, even in the absence of a specific statement, that such names are exempt fromthe relevant protective laws and regulations and therefore free for general use.The publisher, the authors and the editors are safe to assume that the advice and information in thisbook are believed to be true and accurate at the date of publication. Neither the publisher nor theauthors or the editors give a warranty, express or implied, with respect to the material contained herein orfor any errors or omissions that may have been made. The publisher remains neutral with regard tojurisdictional claims in published maps and institutional affiliations.

Printed on acid-free paper

This Springer imprint is published by Springer NatureThe registered company is Springer International Publishing AGThe registered company address is: Gewerbestrasse 11, 6330 Cham, Switzerland

To my beloved Danning and Jing, who makelife a gift.

Preface

Offshore and land-based structures represent large capital investments. They aredesigned to withstand various types of environmental loads such as earthquakes,winds, ocean waves, tidal currents, and ice, and other loads due to explosions,machinery vibrations, dropped objects, and other factors. Many of them essentiallyinduce dynamic and cyclic loading transferred into foundations. Therefore,understanding soil dynamics and foundation modeling is essential to ensure foun-dation and structural integrity and operational functionality. However, in spite ofincreased engineering knowledge, practical problems regarding foundation mod-eling and soil dynamics are in many cases handled unsuccessfully despite largeexpenditures. Moreover, even if engineers can perform sophisticatedcomputer-based analysis tasks, many of them lack an actual understanding of theessential principles of soil dynamics and foundation modeling, and hence of thelinks between theory and applications. This leads to an insurmountable barrierwhen they are asked to validate/verify and provide insightful explanations ofanalysis results, or to further improve designs, which poses a significant safetyhazard and can also result in significant economic loss.

With the objective of providing practical knowledge of foundation modeling anddynamic analysis, which is essential for both offshore and earthquake engineering,the book covers a wide range topics in this area, such as soil behavior, soildynamics, seismic site-response analysis, soil–structure interactions, liquefactions,and modeling and assessment of shallow and deep foundations, considering variouslevels of detail and associated engineering challenges. Differences in soil andfoundation modeling and response due to earthquake and ocean wave loading arealso discussed. To facilitate the understanding and utilization of knowledge for eachtopic, general theory and principles are linked to their engineering applications.Moreover, recent developments in offshore foundation engineering such as anchorpiles, suction piles, large-diameter piles, soil aging effects, and scours are alsodiscussed. Special focus is placed on their engineering applications utilizingstate-of-the-art knowledge.

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Although offshore geotechnical principles are very similar to those of land-basedstructures, for offshore geotechnical engineering applications, soil conditions areoften more difficult to measure and have larger uncertainties, site investigations aremore expensive, and structural loads are usually more significant. Further, the focusof offshore geotechnical design is often placed on capacity control, while founda-tion stiffness remains important for the dynamic response of soil–foundation–structure systems.

Chapter 1 presents the basics of soil mechanics and behaviors, methods fortesting soil strength, and their implications in geotechnical designs. Chapter 2introduces the characteristics and modeling of soil properties under cyclic anddynamic loading, focused on treating soil nonlinearities. Chapters 3 and 4 presentdetails of site-response analysis with a focus on how the response amplification andde-amplification of soil media are accounted for, and how to apply seismic exci-tations in a site-response analysis. Chapter 5 describes soil–structure interactionsand analysis, which estimate the collective response of the entire soil–foundation–structure system to specified ground motions by accounting for effects of kinematicinteraction (normally by site-response analysis), soil–foundation flexibility (foun-dation impedance), and inertia interaction (seismic structural analysis) and whichcan be performed by either direct or substructure approaches. Chapter 6 introducesvarious seismic testing methods including field testing, laboratory element testing,and model testing. Chapter 7 presents the causes and evaluation of soil liquefac-tions, followed by presentations of slope stability due to seismic loading presentedin Chap. 8. Chapter 9 provides a general overview of offshore structures and theircommon and distinguishing features compared to those of land-based structures andalso presents the hydrodynamic modeling to determine the ocean environmentalloading in a seismic analysis. Chapters 10 and 11 present the theoretical back-ground of seismic response spectrum and power spectrum and how earthquakeloading is determined from a seismic hazard point of view. Chapters 12 and 13present the bearing capacity assessment and modeling for shallow foundations.Chapters 14–26 discuss various aspects of pile foundations, such as pile capacityassessment, pile–soil interactions, large-diameter piles, pile group, grout connec-tions, torsional behaviors of piles, scour, seismic assessment of piles, anchor piles,and suction piles. In Chap. 27, design issues for shallow and deep foundations,relevant international design codes, and hierarchy of codes and standards are brieflydiscussed.

The book is intended to serve as an introduction to the subject and also as areference book with advanced topics. A balance between the theoretical andpractical aspects is sought. All the chapters are addressed to practitioners who arelooking for answers to their daily engineering problems, and to students andresearchers who are looking for links between theoretical and practical aspects, andbetween phenomena and analytical explanations. It should also be of use to otherscience and engineering professionals and students with an interest in this subject.

The book is written in such a way that it can be followed by anyone with a basicknowledge of engineering dynamics and soil mechanics.

viii Preface

While the book does not seek to promote any specific “school of thought,” itinevitably reflects this author’s “best practice” and “working habits.” This is par-ticularly apparent in the topics selected and the level of detail devoted to eachof them, their sequences, the choices of mathematical treatments and symbolicnotations, etc. The author hopes that this does not deter readers from seeking to findtheir own “best practice.”

Most of the chapters in this book can be covered in a two-day industry course ina brief manner, a one-week intensive course for either industry or academia, or aone-semester course in an elaborated form for graduate students.

In preparing such a text, it is rather difficult to acknowledge all the help given tothe author. First, I am indebted to geotechnical, earthquake, and offshore engi-neering communities who have undertaken the extensive research and developmentthat has led to accumulated knowledge, methods, and engineering applications inthis field, on which this book is based. I would also like to thank individuals forassistance of various kinds, such as participation in book reviews, technical dis-cussions, and research cooperation. These include (in alphabetical order) the fol-lowing: Atilla Ansal (European Association for Earthquake Engineering), KuvvetAtakan (University of Bergen), Gunnar Bremer (Aker Solutions), Ove TobiasGudmestad (University of Stavanger), Yingcai Han (Fluor Canada), Nils-ChristianHellevig (Aker Solutions), Viggo Karlsen (Statoil), Amir M. Kaynia (NorwegianGeotechnical Institute), Steven L. Kramer (University of Washington), BM Lehane(The University of Western Australia), Conrad Lindholm (NORSAR), LanceManuel (University of Texas at Austin), Peter Middendorp (AllnamicsGeotechnical & Pile Testing Experts), George Mylonakis (University of Bristol),Laurens de Neef (CAPE Holland), Giuliano F. Panza (University of Trieste andChina Earthquake Administration), John Michael Rotter (University of Edinburghand Imperial College), Richard Snell (Oxford University), Douglas Stock (DigitalStructures, Inc. Berkeley), Gary Torosian (GeoTesting Express, Inc.), and RJSWhitehouse (HR Wallingford). Furthermore, I would like to thank NorwegianGeotechnical Institute, Statoil, DongEnergy, BP, and DNV-GL for their coopera-tion on relevant engineering projects. Moreover, there are numerous others notnamed to whom I extend my sincere thanks.

This book has an extensive list of references reflecting both the historical andrecent developments of the subject. I would like to thank all the authors in thereferences for their contribution to the area.

Most importantly, I dedicate this book to my parents Shufeng and Wangeng, mywife Jing, and daughter Danning; I conclude this preface with an expression of deepgratitude to them.

Bergen, Norway Junbo Jia

Preface ix

About this Book

This book presents a comprehensive topical overview of soil dynamics and foun-dation modeling in offshore and earthquake engineering. The spectrum of topicscovered includes, but is not limited to, soil behavior, offshore and land-basedstructures, soil dynamics, seismic testing, site-response analysis, representation anddetermination of seismic ground motions, seismic hazard assessment, soil lique-factions, slope stability, offshore environmental loads, earthquake loads, modelingand assessment of shallow and deep foundations, soil–foundation interactions, andrelevant design codes and recommended practices, design methods. The authorprovides the reader with both theory and practical applications and links themethodological approaches with engineering applications. The book also containsrecent developments in offshore foundation engineering such as large-diameterpiles, anchor piles, suction piles, soil aging effects, and scour estimation. The targetaudience primarily comprises research experts and practitioners in the field ofoffshore, geotechnical, and earthquake engineering, but the book is also beneficialfor graduate students.

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Contents

Part I Soil Behavior and Dynamics

1 Soil Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.2 Soil Classification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31.3 Saturation, Water Table, Drainage, and Capillary Effect . . . . . 5

1.3.1 Saturation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51.3.2 Drainage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61.3.3 Water Table . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 71.3.4 Capillary Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

1.4 Effective Stress . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 81.5 Mohr’s Circle for Describing Stress Condition . . . . . . . . . . . . 131.6 Soil Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

1.6.1 Shear Failure for Cohesionless Soils . . . . . . . . . . . . 181.6.2 Shear Failure for Cohesive Soils . . . . . . . . . . . . . . . 18

1.7 Total Stress Analysis Versus Effective Stress Analysis . . . . . . 211.8 Clay Soil Consistency . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 221.9 Testing Methods to Measure Shear Strength . . . . . . . . . . . . . . 24

1.9.1 Laboratory and Field Test Methods . . . . . . . . . . . . . 241.9.2 Direct Shear Test . . . . . . . . . . . . . . . . . . . . . . . . . . 241.9.3 Triaxial Shear Test . . . . . . . . . . . . . . . . . . . . . . . . . 251.9.4 Vane Shear Test . . . . . . . . . . . . . . . . . . . . . . . . . . . 291.9.5 Standard Penetration Test (SPT) . . . . . . . . . . . . . . . 311.9.6 Cone Penetration Test (CPT) . . . . . . . . . . . . . . . . . . 361.9.7 Other in Situ Testing Methods . . . . . . . . . . . . . . . . . 42

1.10 Soil Stiffness and Poisson’s Ratio . . . . . . . . . . . . . . . . . . . . . 421.11 Consolidation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46

1.11.1 Introduction to Consolidation . . . . . . . . . . . . . . . . . 461.11.2 Effects of Consolidation on Soil Stiffness . . . . . . . . . 471.11.3 Effects of Consolidation for Shallow Foundations . . . 48

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1.11.4 Effects of Consolidation and Aging for DeepFoundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50

1.12 Obtaining Soil Parameters for Engineering Design . . . . . . . . . 531.13 Allowable Stress Design and Load Resistance

Factor Design . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 561.13.1 Allowable Stress Design . . . . . . . . . . . . . . . . . . . . . 561.13.2 Load Resistance Factor Design . . . . . . . . . . . . . . . . 561.13.3 Levels of Reliability Method . . . . . . . . . . . . . . . . . . 691.13.4 Essential Differences Between LRFD and ASD . . . . 701.13.5 Applying Partial Safety Factors in Geotechnical

Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 711.14 Incorporating Uncertainties of Soil Parameters . . . . . . . . . . . . 711.15 General Soil Conditions at Offshore Sites Worldwide . . . . . . . 73

2 Dynamic and Cyclic Properties of Soils . . . . . . . . . . . . . . . . . . . . . 752.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 752.2 Equivalent Linear Soil Models . . . . . . . . . . . . . . . . . . . . . . . . 78

2.2.1 Equivalent Shear Modulus Modeling . . . . . . . . . . . . 782.2.2 Determination of Gmax . . . . . . . . . . . . . . . . . . . . . . 822.2.3 Equivalent Damping Modeling . . . . . . . . . . . . . . . . 86

2.3 Soil Stiffness and Damping Modeling in an Equivalent LinearModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892.3.1 Trends in Dynamic Soil Properties and Strain

Thresholds . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 892.3.2 Stiffness Modeling . . . . . . . . . . . . . . . . . . . . . . . . . 932.3.3 Damping Modeling . . . . . . . . . . . . . . . . . . . . . . . . . 95

2.4 Nonlinear Soil Models . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 972.4.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 972.4.2 Cyclic Nonlinear Soil Models . . . . . . . . . . . . . . . . . 982.4.3 Small Strain Damping Modeling in Time-Domain

Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1002.4.4 Nonlinear Constitutive Soil Models . . . . . . . . . . . . . 103

2.5 Strain Rate Effects Due to Seismic Loading . . . . . . . . . . . . . . 1062.6 Differences Between Soil Properties Subjected to Earthquake

Loadings and Ocean Wave Loadings . . . . . . . . . . . . . . . . . . . 107

3 Site-Response Analysis in GeotechnicalEarthquake Engineering . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1093.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1093.2 Site Period . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115

3.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1153.2.2 Influence of Soil Depth on the Site Period . . . . . . . . 119

3.3 Non-stationary and Peak Ground Motions . . . . . . . . . . . . . . . 1213.3.1 Peak Ground Motions and Their Relationship with

Magnitude and Intensity . . . . . . . . . . . . . . . . . . . . . 121

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3.3.2 Contribution of Body and Surface Wave to GroundMotions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124

3.3.3 Moving Resonance . . . . . . . . . . . . . . . . . . . . . . . . . 1253.4 Measuring Soil Amplification or De-amplification . . . . . . . . . . 1263.5 One-Dimensional Site-Response Analysis . . . . . . . . . . . . . . . . 126

3.5.1 One-Dimensional Seismic Wave PropagationAnalysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 126

3.5.2 One-Dimensional Frequency-Domain Site-Response Analysis Using Equivalent Linear SoilModel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 133

3.5.3 One-Dimensional Site-Response Analysis UsingNonlinear Soil Models . . . . . . . . . . . . . . . . . . . . . . 143

3.6 Surface (Topographic) and Subsurface Irregularities . . . . . . . . 1463.6.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1463.6.2 Effects of Irregular Surface Topology . . . . . . . . . . . . 1473.6.3 Effects of Subsurface Irregularity . . . . . . . . . . . . . . . 149

3.7 Two- and Three-Dimensional Site-Response Analyses . . . . . . . 1513.7.1 Applicability of One-, Two-, and Three-

Dimensional Site-Response Analyses . . . . . . . . . . . . 1513.7.2 Seismic Wave Propagation Effects . . . . . . . . . . . . . . 1523.7.3 Site Geometric Effects . . . . . . . . . . . . . . . . . . . . . . . 155

3.8 Using Site-Response Analysis Results for Seismic Analysis . . . 1593.9 Characteristics of Site Responses . . . . . . . . . . . . . . . . . . . . . . 159

3.9.1 Horizontal Ground Motions . . . . . . . . . . . . . . . . . . . 1593.9.2 Vertical Ground Motions . . . . . . . . . . . . . . . . . . . . . 161

3.10 Vertical Ground Motion Calculations . . . . . . . . . . . . . . . . . . . 1623.10.1 Site-Response Analysis for Calculating Vertical

Ground Motions . . . . . . . . . . . . . . . . . . . . . . . . . . . 1623.10.2 V/H Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 163

3.11 Water Column Effects on Seismic Ground Motions . . . . . . . . . 165

4 Record Selection for Performing Site-SpecificResponse Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1674.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1674.2 Selections of Motion Recordings . . . . . . . . . . . . . . . . . . . . . . 1684.3 Modification of the Recordings to Fit into the Design Rock

Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1694.3.1 Direct Scaling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1694.3.2 Spectrum/Spectral Matching . . . . . . . . . . . . . . . . . . 1694.3.3 Pros and Cons of Direct Scaling and Spectrum

Matching . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1734.4 Performing the Site-Response Analysis Using

Modified/Matched Recordings . . . . . . . . . . . . . . . . . . . . . . . . 1744.5 Sources of Ground Motion Recording Data . . . . . . . . . . . . . . 175

Contents xv

5 Soil–Structure Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1775.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1775.2 Direct and Substructure Approach . . . . . . . . . . . . . . . . . . . . . 178

5.2.1 Direct Analysis Approach . . . . . . . . . . . . . . . . . . . . 1785.2.2 Substructure Approach . . . . . . . . . . . . . . . . . . . . . . 178

5.3 Kinematic Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1805.3.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1805.3.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 181

5.4 Subgrade Impedances and Damping . . . . . . . . . . . . . . . . . . . . 1815.4.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1815.4.2 Applications for Pile Foundations . . . . . . . . . . . . . . 1815.4.3 Applications for Shallow Foundations . . . . . . . . . . . 182

5.5 Inertial Interaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1845.5.1 Objective . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1845.5.2 Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 186

5.6 Effects of Soil–Structure Interaction . . . . . . . . . . . . . . . . . . . . 1865.7 Boundary Modeling in Geotechnical Analysis . . . . . . . . . . . . . 1875.8 Remarks on Substructure Approach . . . . . . . . . . . . . . . . . . . . 189

6 Seismic Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1916.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1916.2 Field Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192

6.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1926.2.2 Low-Strain Field Test . . . . . . . . . . . . . . . . . . . . . . . 1926.2.3 High-Strain Field Test . . . . . . . . . . . . . . . . . . . . . . . 210

6.3 Laboratory Element Testing . . . . . . . . . . . . . . . . . . . . . . . . . . 2116.3.1 Low-Strain Element Test . . . . . . . . . . . . . . . . . . . . . 2116.3.2 High-Strain Element Test . . . . . . . . . . . . . . . . . . . . 217

6.4 Model Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2186.4.1 Shaking Table Test . . . . . . . . . . . . . . . . . . . . . . . . . 2186.4.2 Centrifuge Test . . . . . . . . . . . . . . . . . . . . . . . . . . . . 224

7 Liquefaction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2277.1 Introduction to Liquefaction . . . . . . . . . . . . . . . . . . . . . . . . . . 227

7.1.1 Causes of Liquefactions . . . . . . . . . . . . . . . . . . . . . 2277.1.2 Liquefaction Damages . . . . . . . . . . . . . . . . . . . . . . . 231

7.2 Evaluation of Liquefaction Initiation . . . . . . . . . . . . . . . . . . . 2367.2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2367.2.2 Cyclic Stress Approach . . . . . . . . . . . . . . . . . . . . . . 2377.2.3 Cyclic Strain Approach . . . . . . . . . . . . . . . . . . . . . . 248

7.3 Liquefaction Mitigations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 249

8 Slope Stability Due to Seismic Loading . . . . . . . . . . . . . . . . . . . . . . 2518.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2518.2 Pseudo-Static Analysis Approach . . . . . . . . . . . . . . . . . . . . . . 252

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8.3 Dynamic Stress-Deformation Analysis Approach . . . . . . . . . . 2558.4 Newmark Sliding-Block Approach . . . . . . . . . . . . . . . . . . . . . 256

8.4.1 Rigid-Block Analysis . . . . . . . . . . . . . . . . . . . . . . . 2578.4.2 Decoupled Analysis . . . . . . . . . . . . . . . . . . . . . . . . 2598.4.3 Coupled Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . 2608.4.4 Selection of Analysis Methods . . . . . . . . . . . . . . . . 2608.4.5 Potential of Landslides Based on the Predicted

Displacement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2618.5 Testing Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2628.6 Post-Earthquake Slope Instability Assessment . . . . . . . . . . . . . 2628.7 Landslides . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 263

8.7.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2638.7.2 Assessment of Regional Landslide Potential by

Arias Intensity . . . . . . . . . . . . . . . . . . . . . . . . . . . . 264

Part II Offshore Structures and Earthquake Engineering

9 Offshore Structures and Hydrodynamic Modeling . . . . . . . . . . . . . 2699.1 Introduction to Offshore Structures . . . . . . . . . . . . . . . . . . . . . 269

9.1.1 Offshore Platforms . . . . . . . . . . . . . . . . . . . . . . . . . 2699.1.2 Offshore Wind Turbine Substructures and

Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2779.2 Dynamic Design of Structures . . . . . . . . . . . . . . . . . . . . . . . . 283

9.2.1 Dynamics Versus Statics . . . . . . . . . . . . . . . . . . . . . 2839.2.2 Characteristics of Dynamic Responses . . . . . . . . . . . 2889.2.3 Frequency Range of Dynamic Loading . . . . . . . . . . 294

9.3 Difference Between Offshore and Land-Based Structures . . . . . 2999.4 Hydrodynamic Modeling of Offshore Structures . . . . . . . . . . . 302

9.4.1 Introduction to Hydrodynamic Force Calculation . . . 3029.4.2 Effects of Drag Forces . . . . . . . . . . . . . . . . . . . . . . 3089.4.3 Effects and Determination of Added Mass . . . . . . . . 3089.4.4 Effects of Buoyancy . . . . . . . . . . . . . . . . . . . . . . . . 3109.4.5 Effects and Modeling of Marine Growth . . . . . . . . . 311

10 Representation of Seismic Ground Motions . . . . . . . . . . . . . . . . . . 31510.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31510.2 Earthquake Excitations Versus Dynamic Ocean Wave, Wind,

and Ice Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31610.3 Power Spectrum of Seismic Ground Motions . . . . . . . . . . . . . 319

10.3.1 Introduction to Fourier and Power Spectrum . . . . . . 31910.3.2 Power Spectrum of Seismic Ground Motions . . . . . . 328

10.4 Response Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33010.4.1 Background . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33010.4.2 Elastic Response and Design Spectrum . . . . . . . . . . 332

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10.4.3 Ductility-Modified (Inelastic) Design SpectrumMethod . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 351

10.5 Time History Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35710.5.1 General Method . . . . . . . . . . . . . . . . . . . . . . . . . . . 35710.5.2 Drift Phenomenon and Its Correction . . . . . . . . . . . . 358

11 Seismic Hazard Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36311.1 Seismic Hazard Analysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . 363

11.1.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36311.1.2 Deterministic Seismic Hazard Analysis (DSHA) . . . . 36511.1.3 Probabilistic Seismic Hazard Analysis (PSHA) . . . . . 36711.1.4 Deaggregation (Disaggregation) in PSHA for

Multiple Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . 38511.1.5 Logic Tree Method . . . . . . . . . . . . . . . . . . . . . . . . . 390

11.2 Seismic Hazard Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39211.3 Apply PSHA for Engineering Design . . . . . . . . . . . . . . . . . . . 39511.4 Conditional Mean Spectrum . . . . . . . . . . . . . . . . . . . . . . . . . . 39911.5 The Neo-deterministic Approach . . . . . . . . . . . . . . . . . . . . . . 40511.6 Forecasting “Unpredictable” Extremes . . . . . . . . . . . . . . . . . . 409

Part III Shallow Foundations

12 Bearing Capacity of Shallow Foundations . . . . . . . . . . . . . . . . . . . . 41312.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41312.2 Failure of Shallow Foundations . . . . . . . . . . . . . . . . . . . . . . . 41512.3 Bearing Capacity of Drained Soil . . . . . . . . . . . . . . . . . . . . . . 421

12.3.1 Bearing Capacity Due to General Shear Failure . . . . 42112.3.2 Bearing Capacity Due to Local and Punching Shear

Failure . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42512.3.3 Bearing Capacity for Layered Soil . . . . . . . . . . . . . . 426

12.4 Bearing Capacity for Undrained Clay . . . . . . . . . . . . . . . . . . . 42612.5 Bearing Capacity of Unliquefiable Soil Subjected to Seismic

Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42712.6 Bearing Capacity Control of Soils with Liquefaction Potential

Subjected to Seismic Loading . . . . . . . . . . . . . . . . . . . . . . . . 42812.7 Sliding Stability of Shallow Foundations . . . . . . . . . . . . . . . . 43012.8 Effects of Cyclic Loading on Shallow Foundations . . . . . . . . . 43012.9 Piping Actions and Scour for Shallow Foundations . . . . . . . . . 432

13 Modeling of Shallow Foundation Dynamics . . . . . . . . . . . . . . . . . . 43513.1 Foundation Impedance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43513.2 Combination of Damping for Foundations

and Superstructures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 450

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Part IV Pile Foundations

14 Introduction to Deep Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . 455

15 Capacity Control, Modeling of Pile Head Stiffness,and Mitigation Measures to Increase Pile Capacity . . . . . . . . . . . . 46515.1 Capacity Control of Pile Foundations . . . . . . . . . . . . . . . . . . . 46515.2 Representation of Piles, Surrounding Soils,

and Soil–Pile Interactions . . . . . . . . . . . . . . . . . . . . . . . . . . . 46715.3 Winkler Foundation Modeling . . . . . . . . . . . . . . . . . . . . . . . . 47215.4 Simplified Calculation of Pile Stiffness and Natural

Frequency for Pile–Structure System . . . . . . . . . . . . . . . . . . . 47515.4.1 Stiffness of Pile–Structure System . . . . . . . . . . . . . . 47515.4.2 Pile Head Stiffness . . . . . . . . . . . . . . . . . . . . . . . . . 47715.4.3 Natural Frequency of Non-uniform Beams . . . . . . . . 477

15.5 Increasing Existing Pile Foundation Capacity for OffshoreStructures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 480

16 Lateral Force–Displacement of Piles—p-y Curve . . . . . . . . . . . . . . 48116.1 Introduction to p-y Curve . . . . . . . . . . . . . . . . . . . . . . . . . . . 48116.2 Calculation of pu for Clays . . . . . . . . . . . . . . . . . . . . . . . . . . 48616.3 Calculation of pu for Sands . . . . . . . . . . . . . . . . . . . . . . . . . . 49016.4 Constructing p-y Curves for Clays . . . . . . . . . . . . . . . . . . . . . 49116.5 Constructing p-y Curves for Sands . . . . . . . . . . . . . . . . . . . . . 49516.6 Effects of Cyclic Loading on p-y Curves and Structural

Dynamic Response . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49816.7 Effects of Dynamic Loading on p-y Curves . . . . . . . . . . . . . . 50316.8 Effects of Pile Diameter on Lateral Load–Displacement

Behavior . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50516.8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50516.8.2 Effects of Pile Diameter Under Sand Soil

Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50816.8.3 Effects of Pile Diameter Under Clay Soil

Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51216.9 Hybrid Spring Model for Modeling Piles’ Lateral

Force–Displacement Relationship . . . . . . . . . . . . . . . . . . . . . . 518

17 Axial Force–Displacement of Piles: t-z and Q-z Curve . . . . . . . . . . 52117.1 Pile–Soil Modeling Under Axial Pile Loading . . . . . . . . . . . . 52117.2 Axial Compression Capacity . . . . . . . . . . . . . . . . . . . . . . . . . 52217.3 Axial Tension Capacity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52917.4 Determining Unit Friction Capacity for Cohesive Soils . . . . . . 531

17.4.1 Friction Capacity for Highly Plastic Claysby API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 531

17.4.2 Friction Capacity for Other Types of Claysby API . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 532

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17.4.3 Friction Capacity by Revised API Method(a-Method) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 533

17.4.4 Friction Capacity for Long Piles in Clay . . . . . . . . . 53317.4.5 b-Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53417.4.6 k-Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 535

17.5 Determining Unit Friction Capacity for Cohesionless Soils . . . 53517.5.1 Unit Friction Capacity by API 1993 Method . . . . . . 53617.5.2 Unit Friction Capacity by API 2000 Method . . . . . . 537

17.6 Modeling of Pile–Soil Friction Behavior by FEM . . . . . . . . . . 53817.7 Modeling of t-z Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53917.8 Determining Unit End-Bearing Capacity for Cohesive Soils . . . 54017.9 Determining Unit End-Bearing Capacity for Cohesionless

Soils . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54117.10 Modeling of Q-z Curves . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54117.11 Effects of Soil Layer Boundaries on End-Bearing Capacity . . . 54217.12 Soil Plugging . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54317.13 Recently Developed CPT-Based Methods to Assess the Axial

Pile–Soil Interaction Capacity . . . . . . . . . . . . . . . . . . . . . . . . 54517.13.1 Skin Friction Calculation for CPT-Based Method . . . 54617.13.2 End-Bearing Capacity Calculation for CPT-Based

Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54817.13.3 Comments on the CPT-Based Methods . . . . . . . . . . 552

17.14 Ultimate End-Bearing Capacity from Tests . . . . . . . . . . . . . . . 55417.15 Effects of Cyclic Loading on Axial Capacity of Piles . . . . . . . 554

18 Torsional Moment–Rotation Relationship . . . . . . . . . . . . . . . . . . . . 55918.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 55918.2 Behavior of Single Piles Under Torsion . . . . . . . . . . . . . . . . . 56018.3 Behavior of Pile Groups Under Torsion . . . . . . . . . . . . . . . . . 564

19 Modeling, Response Calculation, and Design of Piles UnderSeismic Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 56519.1 Loading of Piles During Earthquakes . . . . . . . . . . . . . . . . . . . 56519.2 Pseudo-static Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 568

19.2.1 Inertia Loading on Piles . . . . . . . . . . . . . . . . . . . . . 56819.2.2 Kinematic Loading and Pile Response . . . . . . . . . . . 569

19.3 The Location for Transferring the Earthquake Input Energyfrom Soils to Piles or Shallow Foundations . . . . . . . . . . . . . . 576

19.4 Simple Modeling of Pile Impedance . . . . . . . . . . . . . . . . . . . . 57719.5 Determination of Pile Impedance . . . . . . . . . . . . . . . . . . . . . . 57919.6 Kinematic and Inertia Loading Modeling in the Direct

Analysis Approach . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 584

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20 Scour for Pile Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58920.1 Introduction to Scour . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58920.2 Influence of Scours . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59220.3 Scour Modeling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59520.4 Determination of Scour Depth for Single Piles

and Bridge Piers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 59520.5 Scour Depth Influenced by Pile Groups . . . . . . . . . . . . . . . . . 59720.6 Influence of Scour on Pile’s Capacity . . . . . . . . . . . . . . . . . . . 599

20.6.1 Influence of Scour on Axial Pile Capacity . . . . . . . . 59920.6.2 Influence of Scour on Lateral Pile Capacity . . . . . . . 60020.6.3 The Consideration of Scour in Pile Designs

by DNV-OS-J101 . . . . . . . . . . . . . . . . . . . . . . . . . . 600

21 Effects of Pile Group, Adjacent Structures, and ConstructionActivities . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60121.1 Introduction to Pile Group . . . . . . . . . . . . . . . . . . . . . . . . . . . 60121.2 Pile Group Effects Under Axial Loading . . . . . . . . . . . . . . . . 605

21.2.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60521.2.2 Modifying Friction Resistance . . . . . . . . . . . . . . . . . 60821.2.3 Modifying Tip Resistance . . . . . . . . . . . . . . . . . . . . 609

21.3 Pile Group Effects Under Lateral Loading . . . . . . . . . . . . . . . 60921.3.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 60921.3.2 Modifying Soil Resistance . . . . . . . . . . . . . . . . . . . . 612

21.4 Effects of Cyclic Loading on Pile Group Behavior . . . . . . . . . 61521.5 Effects of Dynamic Loading on Pile Group Behavior . . . . . . . 615

21.5.1 General . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61521.5.2 Modifying Pile Resistance Due to Dynamic

Loading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61521.6 Modifying Pile Displacement to Account for Both Pile Group

and Dynamic Loading Effects . . . . . . . . . . . . . . . . . . . . . . . . 61621.7 Pile Cap . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61821.8 Influence of Adjacent Structures and Construction Activities

on the Existing Piled Foundations . . . . . . . . . . . . . . . . . . . . . 61921.8.1 Problem Description . . . . . . . . . . . . . . . . . . . . . . . . 61921.8.2 Pile–Soil Interaction Influenced by the Presence

of Spudcan . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62021.8.3 Influence of Pile–Soil Interaction Due to

Construction Activities . . . . . . . . . . . . . . . . . . . . . . 622

22 Grout Connections . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62522.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 62522.2 Grout Connection Capacity Control . . . . . . . . . . . . . . . . . . . . 62722.3 Typical Mechanical Properties of Grout . . . . . . . . . . . . . . . . . 627

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23 Vertical Piles Versus Inclined/Battered/Raked Piles . . . . . . . . . . . . 62923.1 Introduction to Inclined/Battered Piles . . . . . . . . . . . . . . . . . . 62923.2 Seismic Performance of Pile Groups with Battered Piles . . . . . 62923.3 Wave- and Wind-Induced Response of Pile Group with

Battered Piles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 632

24 Negative (Downward) Friction and Upward Movement . . . . . . . . . 63724.1 Negative Friction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63724.2 Upward Movement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 640

25 Anchor Piles . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64125.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64125.2 Behavior of Anchor Lines . . . . . . . . . . . . . . . . . . . . . . . . . . . 643

25.2.1 Behavior of Anchor Lines on Seabed . . . . . . . . . . . . 64325.2.2 Behavior of Buried Anchor Lines . . . . . . . . . . . . . . 644

25.3 Anchor Pile Padeye(s) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64625.4 Seismic Response of Anchor Pile . . . . . . . . . . . . . . . . . . . . . . 64825.5 Required Safety Factors for Offshore Anchor Pile Design . . . . 64825.6 Fatigue Capacity Control of Anchor Line–Pile Connection . . . 649

25.6.1 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64925.6.2 Derivation of Hot-Spot Stress . . . . . . . . . . . . . . . . . 652

26 Suction Piles/Caissons . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65526.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65526.2 Suction Pile Installations . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65626.3 Modeling and In-place Capacity Control for Suction Piles . . . . 65826.4 Modeling of Suction Piles Subjected to Seismic Loading . . . . 66126.5 Advantages of Suction Piles/Caissons . . . . . . . . . . . . . . . . . . . 66426.6 Engineering Applications . . . . . . . . . . . . . . . . . . . . . . . . . . . . 665

26.6.1 Application for Offshore Structures . . . . . . . . . . . . . 66526.6.2 Application as Deep-Water Anchors . . . . . . . . . . . . 66726.6.3 Application for Subsea Production Facility

Foundations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 668

27 General Design Issues for Offshore Foundations and RelevantInternational Codes and Guidelines . . . . . . . . . . . . . . . . . . . . . . . . 669

Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 673

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 675

Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 727

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About the Author

Dr. Junbo Jia is an engineering expert at Aker Solutions, Norway. He is currentlya committee member of ISO TC67/SC7 Fixed Steel Structures and an invitedmember of Eurocode 3. He has been invited as speakers and lecturers for industrytraining and university graduate courses, and permanent members of Ph.D. exam-ination committees by various organizations and research institutes. Dr. Jia haspublished two other Springer engineering monographs on Applied DynamicAnalysis and Seismic Engineering. He is currently editing a handbook volumeentitled “Structural Engineering in Vibrations, Dynamics and Impacts”, to bepublished by CRC press.

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