1st Edition

Fundamentals of Deep Excavations

By Chang-Yu Ou Copyright 2022
    486 Pages 412 B/W Illustrations
    by CRC Press

    486 Pages 412 B/W Illustrations
    by CRC Press

    Excavation is an important segment of foundation engineering (e.g., in the construction of the foundations or basements of high-rise buildings, underground oil tanks, or subways). However, the excavation knowledge introduced in most books on foundation engineering is too simple to handle actual excavation analysis and design. Moreover, with economic development and urbanization, excavations go deeper and are larger in scale. These conditions require elaborate analysis, design methods and construction technologies.

    This book is aimed at both theoretical explication and practical application. From basic to advanced, this book attempts to achieve theoretical rigor and consistency. Each chapter is followed by a problem set so that the book can be readily taught at senior undergraduate and graduate levels. The solution to the problems at the end of the chapters can be found on the website (http://www.ct.ntust.edu.tw/ou/). On the other hand, the analysis methods introduced in the book can be used in actual analysis and design as they contain the most up-to-date knowledge. Therefore, this book is suitable for teachers who teach foundation engineering and/or deep excavation courses and engineers who are engaged in excavation analysis and design.

    1 Introduction to the analysis and design of excavations

    1.1 Geological investigation and soil tests

    1.2 Conditions of the adjacent properties

    1.3 Confirmation of the conditions of an excavation site

    1.4 Design criteria

    1.5 Collecting case histories of the nearby excavations

    1.6 Auxiliary methods

    1.7 Excavation analyses

    1.8 Layout of the strutting system

    1.9 Monitoring system

    1.10 Protection of neighboring properties

    2 Engineering properties of soils and geotechnical analysis

    2.1 Introduction

    2.2 Engineering properties

    2.3 Principle of effective stress

    2.4 Failure of soils

    2.5 Characteristics of drained shear strength of soils

    2.6 Characteristics of undrained shear strength of saturated cohesive soils

    2.7 Undrained shear strength of unsaturated cohesive soils

    2.8 Deformation characteristics of soils

    2.9 Geotechnical analysis method

    2.10 Stress paths in excavations


    3 Excavation methods and lateral supporting systems

    3.1 Introduction

    3.2 Excavation methods

    3.3 Retaining walls

    3.4 Strutting systems

    3.5 Selection of a retaining strut system

    3.6 Construction of the TNEC project


    4 Lateral earth pressure

    4.1 Introduction

    4.2 Lateral earth pressure at rest

    4.3 Rankine’s earth pressure theory

    4.4 Coulomb’s earth pressure theory

    4.5 General discussion of various earth pressure theories

    4.6 Earth pressure for design


    5 Stability analysis

    5.1 Introduction

    5.2 Types of factors of safety

    5.3 Base shear failure

    5.4 Free earth support method and fixed earth support method

    5.5 Base shear failure of strutted walls

    5.6 General discussion of analysis methods of base shear failure

    5.7 Case study of base shear failure

    5.8 Base shear failure of cantilever walls

    5.9 Upheaval failure

    5.10 Sand boiling

    5.11 Case study of sand boiling


    6 Stress and deformation analysis: simplified method

    6.1 Introduction

    6.2 Analysis of settlement induced by the construction of diaphragm walls

    6.3 Characteristics of wall movement induced by excavation

    6.4 Characteristics of ground movement induced by excavation

    6.5 Characteristics of excavation bottom movement induced by excavation

    6.6 Time-dependent movement

    6.7 Analysis of wall movements induced by excavation

    6.8 Analysis of surface settlements induced by excavation

    6.9 Three-dimensional excavation behavior

    6.10 Stress analysis


    7 Stress and deformation analysis: beam on elastic foundation method

    7.1 Introduction

    7.2 Basic principles

    7.3 Formulation

    7.4 Simulation of construction sequence

    7.5 Estimation of coefficient of subgrade reaction

    7.6 Estimation of coefficient of the at-rest earth pressure

    7.7 Estimation of structural parameters

    7.8 Direct analysis and back analysis

    7.9 Computation of ground surface settlement

    7.10 Limitations of beam on elastic foundation method


    8 Stress and deformation analysis: finite element method

    8.1 Introduction

    8.2 Framework and principles

    8.3 Effective stress analysis and total stress analysis

    8.4 Commonly used soil models and related parameters

    8.5 Determination of soil parameters

    8.6 Determination of initial stresses

    8.7 Structural material models and related parameters

    8.8 Mesh generation

    8.9 Plane strain analysis and 3D analysis

    8.10 Finite element stability analysis

    8.11 FEA procedure


    9 Dewatering in excavations

    9.1 Introduction

    9.2 Goals of dewatering

    9.3 Methods of dewatering

    9.4 Well theory

    9.5 Pumping tests

    9.6 Dewatering plan for an excavation

    9.7 Dewatering and ground settlement


    10 Design of retaining structural components

    10.1 Introduction

    10.2 Design methods and factors of safety

    10.3 Retaining walls

    10.4 Structural components in braced excavations

    10.5 Strut systems

    10.6 Structural components in anchored excavations

    10.7 Anchor systems

    10.8 Tests of anchors


    11 Excavation and protection of adjacent buildings

    11.1 Introduction

    11.2 Allowable settlement of buildings

    11.3 Assessment of building safety and design of protection measures

    11.4 Adjustment of construction sequence

    11.5 Strengthening the strut-retaining system

    11.6 Soil improvement

    11.7 Cross walls

    11.8 Buttress walls

    11.9 Micro piles

    11.10 Underpinning

    11.11 Construction defects and remedial measures

    11.12 Building rectification methods


    12 Monitoring systems

    12.1 Introduction

    12.2 Elements of a monitoring system

    12.3 Principles of strain gauges

    12.4 Measurement of movement and tilt

    12.5 Measurement of stress and force

    12.6 Measurement of water pressure and groundwater level

    12.7 Other measurement objects

    12.8 Plan of monitoring systems

    12.9 Application of monitoring systems


    Appendix A: Conversion factors

    Appendix B: Soil properties at the TNEC excavation site

    Appendix C: Definition of plane strain


    Chang-Yu Ou, Ph.D., is a Chair Professor of the Department of Civil and Construction Engineering at the National Taiwan University of Science and Technology, Taipei, Taiwan. He received his doctoral degrees from Stanford University in 1987. He is the chair of the ATC6 of the International Society for Soil Mechanics and Geotechnical Engineering (ISSMGE). He was the Dean of the College of Engineering at the National Taiwan University of Science and Technology and the President of the Taiwan Geotechnical Society.

    His areas of interest are deep excavations, soil behavior, soft ground tunneling, and ground improvement. He has published more than 200 journal and conference papers. He has received three outstanding research awards and received a research fellow award from the National Science Council of Taiwan. He was also awarded many journal paper awards. In addition to publishing the book Deep Excavation: Theory and Practice with Taylor & Francis, he has also published three deep excavation books in the Chinese language. Because of his outstanding research results, he has participated in many large-scale projects related to deep excavations as a reviewer, designer, or analyst.