Analysis of Pile Foundations Subject to Static and Dynamic Loading

Amir M. Kaynia

• Publisher: CRC Press
• Year: 2021
• Print ISBN: 9780367374167
• eBook ISBN: 9781000398588
• Edition: 1
• Topic: Technology & Engineering
• Subtopic: Civil Engineering
• Index: Technology & Engineering

This book presents computational tools and design principles for piles used in a wide range of applications and for different loading conditions. The chapters provide a mixture of basic engineering solutions and latest research findings in a balanced manner. The chapters are written by world-renowned experts in the field. The materials are presented in a unified manner based on both simplified and rigorous numerical methods.

The first four chapters present the basic elements and steps in analysis of piles under static and cyclic loading together with clear references to the appropriate design regulations in Eurocode 7 when relevant. The analysis techniques cover conventional code-based methods, solutions based on pile-soil interaction springs, and advanced 3D finite element methods. The applications range from conventional piles to large circular steel piles used as anchors or monopiles in offshore applications.

Chapters 5 to 10 are devoted to dynamic and earthquake analyses and design. These chapters cover a range of solutions from dynamic pile-soil springs to elasto-dynamic solutions of large pile groups. Both linear and nonlinear soil behaviours are considered along with response due to dynamic loads and earthquake shaking including possible liquefaction.

The book is unique in its unified treatment of the solutions used for static and dynamic analysis of piles with practical examples of application. The book is considered a valuable tool for practicing engineers, graduate students and researchers.

Chapter 1

Design of piles for static loads

Christos Vrettos

Technical University of Kaiserslautern

Contents

1.1 Introduction

1.2 Types of piles

1.3 Design principles

1.4 Single piles and pile groups under vertical loading

1.4.1 Pile resistance from tests

1.4.1.1 Static load tests

1.4.1.2 Impact and dynamic load tests

1.4.2 Pile resistance from empirical correlations

1.4.3 Code-based verification of limit states

1.4.3.1 Bearing capacity verification

1.4.3.2 Serviceability verification

1.4.4 Settlement of single piles

1.4.4.1 Approximate closed-form solutions

1.4.4.2 Load-transfer approach

1.4.4.3 Continuum-based solutions

1.4.5 Bearing capacity of pile groups

1.4.5.1 Piles in compression

1.4.5.2 Piles in tension

1.4.6 Settlement of pile groups

1.4.6.1 Methods of analysis

1.4.6.2 Simplified methods

1.4.6.3 Interaction factor method

1.4.6.4 Continuum-based numerical methods

1.4.7 Piled raft foundations

1.5 Single piles and pile groups under lateral loading

1.5.1 General

1.5.2 Lateral resistance of single piles

1.5.3 Deflection of single piles

1.5.3.1 Methods of analysis

1.5.3.2 Subgrade modulus approach

1.5.3.3 Load-transfer approach

1.5.3.4 Continuum-based solutions

1.5.3.5 Comparison between continuum-based solutions and subgrade modulus approach

1.5.4 Lateral bearing capacity of pile groups

1.5.5 Deflection of pile groups

References

1.1 Introduction

Piles are used in the foundation of high-rise buildings, towers, or bridges for transferring and distributing structural loads into deeper, load-bearing layers. Pile foundations are relatively expensive, but they are often an economical alternative to raft foundations. They are often installed in relatively competent ground primarily aiming at fulfilling strict serviceability criteria in terms of settlement or tilt. Design considerations shall take into account the functional significance of the structure, the level of confidence in the soil parameters necessary for proper pile design, the adequacy of the analysis tools to assess pile-soil-structure interaction and load transfer mechanisms, and the extent of construction controls. Although pile load tests are expensive and time-consuming, they are indispensable for confirming and optimizing a pile foundation design in terms of number, pile length, and layout of piles. Especially for uncertain subsoil conditions, a carefully planned pile load test program prior to construction will usually reduce overall foundation costs by allowing for a lower factor of safety in terms of load capacity and a more reliable estimation of differential settlements under service loads. Equally important is the execution in the field by specialized contractors, in particular when soft soil layers of largely unknown characteristics are involved or when alternative, unconventional construction proposals are evaluated for reducing costs. Despite the advanced state-of-practice, many critical issues are still under research, in particular with novel applications of existing technologies, e.g., offshore wind developments.

Numerous studies during the last decades have addressed the behavior of single piles, and much knowledge has been gained mostly from instrumented pile load tests. However, piled foundations comprise mostly pile groups of various sizes that respond to loading through interaction with the surrounding soil along their shaft and their base. Due to this complex interaction, the behavior of a pile group is different from that of a single pile dependent on the pile layout (diameter and length of individual piles, pile spacing), the soil properties, and the load characteristics. The foundation behavior becomes more intricate when the topsoil layer has sufficient strength to participate in the bearing mechanism transforming the entire foundation to a piled raft foundation. In that case, the performance of the foundation in terms of serviceability is the main concern, which requires more advanced design concepts and analysis tools. The state of the art has been presented in the overview articles by Poulos (1989), Randolph (2003), and Mandolini et al. (2005) and in more detail in Kempfert et al. (2003), and in the books by Reese & Van Impe (2011), Fleming et al. (2009), Viggiani et al. (2012), Guo (2013), and Tomlinson & Woodward (2015).

While most of the solutions and design principles presented in this chapter are universal, more focus is placed on European practice in connection with the limit state design concepts of the Structural Eurocodes that are also adopted in many countries outside the European Union. EN 1997 (Eurocode 7 or EC7 in short form) is the relevant code for geotechnical design, cf. Frank et al. (2005), Bo...

Table of contents

• Cover
• Half Title
• Title Page
• Copyright Page
• Table of Contents
• Preface
• Editor
• Contributors
• 1 Design of piles for static loads
• 2 Analysis of laterally loaded pile foundations using the subgrade reaction method
• 3 Design of monopiles supporting offshore wind turbines using finite element analysis
• 4 Design of suction piles for offshore applications
• 5 Simplified models for axial static and dynamic analysis of pile foundations
• 6 Simplified models for lateral static and dynamic analysis of pile foundations
• 7 Inelastic stiffnesses of floating pile groups
• 8 Design of piles under seismic loading
• 9 Pile foundations in liquefiable soils
• 10 Analysis and characteristics of dynamic response of large pile groups
• Index