3-D finite element investigation of discrete deadman anchor for earth retaining wall. PhD thesis ...

286 Pages·2017·5.29 MB·English

by  Christine Middleton

3-D F E I
INITE LEMENT NVESTIGATION
O
F
D D A
ISCRETE EADMAN NCHOR
F
OR
E R W
ARTH ETAINING ALL

C K S
HAI OH IONG

T U O N
HE NIVERSITY F OTTINGHAM
2015
3-D F E I
INITE LEMENT NVESTIGATION
O
F
D D A
ISCRETE EADMAN NCHOR
F
OR
E R W
ARTH ETAINING ALL

C K S
HAI OH IONG
(M. Eng. (Hons.), the University of Nottingham)

A THESIS SUBMITTED
FOR THE DEGREE OF DOCTOR OF PHILOSOPHY
DEPARTMENT OF CIVIL ENGINEERING
THE UNIVERSITY OF NOTTINGHAM
2015
Dedicated to my mother Mdm. Tan Yoke Heong
for her understanding and endless love

i
ACKNOWLEDGEMENT

I would like to take this opportunity to express my sincere appreciation to
my Ph.D. supervisor at the University of Nottingham, Ir. Dr. Chan Swee Huat.
This thesis could not have been accomplished without his excellent
guidance, useful advice and perennial encouragement.
Sincerely, I would also like to express my heartfelt gratitude to Dr. Sandy
Kok Sien Ti, Dr. Song Ki Il and Dr. Mostapha Boulbibane from the
Department of Civil engineering for their helpful advice and invaluable
guidance during the course of my thesis.
Furthermore, grateful acknowledgement is made to the Engineering
Computer Laboratory Technician, Mr. Kumaravehlo S/O Bathumalai for his
effort in installing PLAXIS 3D on my workstation.
I must record my irreparable debt to my family and relatives for their
support and encouragement. Last but not least, I would like to thank my
fellow friends, colleagues and staff members for giving me priceless
support throughout this thesis.

ii
PERFACE

The following publications were published during the term of candidature:
1. Chai, K. S. & Chan, S. H. (2014). A Study on Finite Element Modelling
of Earth Retaining Wall Anchored by Deadman Anchor. ICSMGE
2014: International Conference on Soil Mechanics and Geotechnical
Engineering, Paris, France.
2. Chai, K. S. & Chan, S. H. (2015). Evaluate on the Pull-out of Discrete
Deadman Anchorage in Sand. Geotechnical Engineering Journal of
the SEAGS and AGSSEA. (Submitted)

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ABSTRACT

In the past several years, considerable attention has been given to the
ultimate horizontal pull-out resistance of vertical deadman anchors, which
are usually used together with earth retaining wall. Unfortunately, no
significant effort has been made to understand/study the behaviour of
discrete deadman anchor in earth retaining wall (anchored wall) subjected
to the deflection of earth retaining wall. Therefore, this research aims to
fill up this gap.
The study on the behaviour of single-plate discrete deadman anchor in
anchored wall subjected to the deflection of earth retaining wall is carried
out by three-dimensional (3-D) finite element analysis adopting finite
element software named PLAXIS. The behaviour of discrete deadman
anchor is studied by investigating the effects of several key factors. These
include the effects of length of tie rod, embedment depth of anchor, spacing
between deadman anchors, friction angle of soil, depth of anchored wall,
and stiffness of anchored wall.
Practicing geotechnical engineers are able to understand the interactions
among soil-anchor-wall by studying the effects of several key factors on the
behaviour of discrete deadman anchor. This allows practicing geotechnical
iv
engineers to determine the potential failure mechanisms and hence
provide the most suitable design of anchored wall in geotechnical
engineering.
Furthermore, the effects of abovementioned key factors are summarised
and design charts are proposed for the preliminary design of anchored wall.
The design charts are developed based on limiting the wall deflection to
0.5% of excavation height. The major contribution of this research is the
development of design charts for the preliminary design of anchored wall.
These design charts may be implemented during early design stages, which
serves the purpose for earthwork planning, cost estimation, bill of quantity
and others. These design charts are set as a guideline for the preliminary
design.
Last by not least, the embedment depth of deadman anchor in this research
is studied up to 3.0m deep. Deadman anchorage system embedded deeper
than 3.0m from ground surface is considered to be impractical due to the
difficulty in installation and increase of construction cost and time.

Keywords: 3-D finite element analysis, discrete deadman anchor, earth
retaining wall, sand.

v
TABLE OF CONTENTS

ACKNOWLEDGEMENT ......................................................................................... II
PERFACE ......................................................................................................... III
ABSTRACT ..........................................................................................................IV
TABLE OF CONTENTS .........................................................................................VI
LIST OF FIGURES ...............................................................................................XIII
LIST OF TABLES.............................................................................................. XXVI
NOMENCLATURE ........................................................................................... XXIX
CHAPTER 1 INTRODUCTION ........................................................................... 1
INTRODUCTION ....................................................................................................... 1
BACKGROUND ......................................................................................................... 3
Earth Retaining Wall ...................................................................................... 3
Anchored Wall ........................................................................................ 6
Types of Anchorage for Anchored Wall ................................................... 7
Deadman Anchor ................................................................................... 8
OBJECTIVES AND SCOPE OF WORK .................................................................... 11
THESIS OUTLINE ................................................................................................. 12

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CHAPTER 2 LITERATURE REVIEW ............................................................. 14
INTRODUCTION .................................................................................................... 14
LATERAL EARTH PRESSURE THEORY ............................................................... 14
Rankine’s Theory ............................................................................................. 15
Coulomb’s Theory ........................................................................................... 16
Logarithmic Spiral Theory .......................................................................... 16
FAILURE MECHANISMS OF EARTH RETAINING WALL .................................... 17
Deep Seated Failure ....................................................................................... 18
Rotational Failure .......................................................................................... 18
Flexural Failure ............................................................................................... 18
Anchorage Failures ........................................................................................ 20
Anchor Passive Failure ...................................................................... 21
Tie Rod Failure ..................................................................................... 22
Bearing Plate Failure .......................................................................... 22
HISTORICAL REVIEW .......................................................................................... 22
Analytical Studies ........................................................................................... 23
Summary of Analytical Studies ...................................................... 40
Experimental Studies..................................................................................... 40
Summary of Experimental Studies ............................................... 49
Field Test Studies ............................................................................................ 49
SUMMARY ............................................................................................................. 50
CHAPTER 3 METHODOLOGY ......................................................................... 54
INTRODUCTION .................................................................................................... 54
FINITE ELEMENT ANALYSIS (FEA) .................................................................. 54
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PROTOTYPE CONFIGURATION ............................................................................ 56
DESIGN CRITERIA ................................................................................................ 58
BEHAVIOUR OF DISCRETE DEADMAN ANCHORAGE SYSTEM .......................... 58
PLAXIS MODEL .................................................................................................. 60
3-D Model ........................................................................................................... 60
Soil ............................................................................................................. 60
Earth Retaining Wall and Deadman Anchor ............................. 61
Tie Rod ..................................................................................................... 62
Material ................................................................................................... 62
Boundary Conditions ......................................................................... 65
Mesh Investigation .............................................................................. 66
2-D Model ........................................................................................................... 70
Soil ............................................................................................................. 70
Earth Retaining Wall and Deadman Anchor ............................. 71
Tie Rod ..................................................................................................... 72
VERIFICATION OF FINITE ELEMENT SOFTWARE ............................................. 72
SUMMARY ............................................................................................................. 75
CHAPTER 4 1-G SMALL SCLAE LABORATORY TEST .............................. 77
INTRODUCTION .................................................................................................... 77
1-G SMALL-SCALE LABORATORY TEST SET UP ............................................... 78
Sand Box ............................................................................................................. 78
Deadman Anchorage System ..................................................................... 80
Pull-out System ................................................................................................ 81
SOIL CHARACTERISATION .................................................................................. 84
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