PARAMETRIC STUDY OF EXCAVATION WITH SHEET PILE BY PLAXIS
HANA `AIFAH A. S. SUHAILI
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PARAMETRIC STUDY OF EXCAVATION WITH SHEET PILE BY PLAXIS
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HANA'AIFAH BTE A. S. SUHAILI
A Project Report Submitted in Partial Fulfillment for the
Bachelor of Degree of Engineering (Civil) with Honours in the Faculty of Engineering Universiti Malaysia Sarawak
1999
Borang Penyerahan Tesis Universiti Malaysia Sarawak
BORANG PENYERAHAN TESIS
Judul PARAMETRIC STUDIES OF EXCAVATION WITH SHEET PILE BY PLAXIS.
SESI PENGAJIAN: 1998/99
Saya HANA'AIFAH BTE A. S. SUHAILI
mengaku membenarkan tesis ini disimpan di Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut:
I Hakmilik kertas projek im adalah dibawah nama penulis melainkan penulisan sebagai projek bersama dan dibiayai oleh UNIMAS, hakmiliknya adalah kepunyaan UNIMAS.
2 Naskhah salinan didalam bentuk kertas atau mikro hanya boleh dibuat dengan kebenaran bertulis daripada penulis
3 Pusat khidmat maklumat Akademik, UNIMAS dibenarkan membuat salinan untuk pengajian mereka.
4 Kertas projek hanya boleh diterbitkan dengan kebenaran penulis. Bayaran royalti adalah mengikut kadar yang dipersetujui kelak.
5' Saya membenarkan/tidak membenarkan Perpustakaan membuat kertas salinan projek im sebagai bahan pertukaran diantara institusi pengajian tinggi.
6 '' Sila tandakan ( )
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SULZT (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan Malaysia seperti yang termaktub didalam AKTA RAHSIA RASMI 1972).
TERHAD (Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/badan dimana penyelidikan dijalankan)
TIDAK TERHAD Po
Disahkan oleh
titiLc, C,
(TANDAT. GN PENULIS) (TANDA ANGAN PENYELIA)
Alamat tetap.
Pen Surat 494, En Ahmad Kamal bin Abdul Aziz
89807 Beaufort, Nama Penyelia
SABAH
T'arikh
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Jika Kertas Projek im SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi berkenaan dengan menyertakan sekali tempoh kertas
projek
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APPROVAL SHEET
This project report attached here to, entitled "Parametric Studies Of Excavation With Sheet Pile By PLAXIS", prepared and
submitted by Hana'sifah bte. A. S. Suhaili in partial fulfilment of the requirement for the degree of Bachelor of Engineering (CIVIL) is hereby accepted.
Date:
2 2/ýa/ý-7
(En. Ahmad Kamal bin Abdul Aziz) Lecturer
Civil Engineering Department Faculty Of Engineering
University Malaysia Sarawak
R
(`f-iana'aifah"A. S Suhaili) Peti Surat 494,
89807 Beaufort, Sabah.
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Date:
111
Dedicated to my
papa & mama, brothers & Sisters, Friends & loves one.
iv
ACKNOWLEDGEMENTS
My most sincerely thanks to people who have contributed towards the preparation of this project. Firstly, thank to Mr. Ahmad Kamal, project supervisor, for his guidance, advices, comments and encouragement's through out this project. Thanks also to all lectures and staffs of the engineering Faculty, UNIMAS, for their strong supports.
Not forgetting my family, especially to my father, En. Suhaili bin Abdul Shatar and my mother, Puan Salmah bte. Mohamad, brothers and sisters, Anif, Aneem, Ida and Nijan, thank's for all the helps and motivation alone the way to completing this project.
Acknowledgement will not be complete without mentioning all my friends especially Nor, Cate, Adi, Kak Jie and my ex-housemate at Bangalow 41, Kolej Sri Muara, who have given their constant support and encouragement. To all those named above and any others, who may have been omitted, I'm extremely thankful.
V
ABSTRACT
This project presents a parametric study about activities of excavation by using Finite Element Method (FEM) that is Plasticity Axisymmetri Program or PLAXIS. The aim of this project was to identify the effect caused by a few factors on excavation activities. In this study, dimension for the excavation happened when data put into the program first. Besides, the data involved parameter such as its amount of struts and stiffness, usage of different height of sheet pile and settlement effect was also being analyzed. Apart from that, the results of
comparison can be seen especially on the contour diagram.
Meanwhile, the moment and force that has been reacted toward the sheet pile can be figure out together with the values. From the analysis that has been conducted, it was showed that the parameter factors should be look into even though in theory before being applied to practical works.
vi
ABSTRAK
Projek ini adalah kajian parameter yang melibatkan aktiviti pengorekan dengan menggunakan Kaedah unsur Terhingga iaitu Pengaturcaraan Keplastikan Simetri Sepaksi. Kandungan kajian ini adalah untuk mengenalpasti kesan yang berlaku ke atas pengorekan dengan berdasarkan faktor
- faktor parameternya. Dalam kajian ini, dimensi bagi pengorekan dapat dilihat dengan memasukkan data - data ke dalam program tersebut terlebih dahulu. Di samping itu, data data berkaitan seperti jumlah tetupang dan kekukuhannya,
penggunaan ketinggian cerucuk keping yang berbeza dan kesan mendapannya turut dianalisis. Perbandingan dapat dilihat terutama pada gambarajah kontur yang terhasil setelah siap dianalisis. Selain itu, momen dan daya yang bertindak terhadap cerucuk keping turut dihasilkan beserta nilai-nilainya sekali. Daripada analisis yang dijalankan didapati faktor faktor parameter amatlah perlu ditikberatkan walaupun ia dijalankan secara teori semata sebelum diaplikasikan kepada kerja - kerja praktikal.
Vii
TABLE OF CONTENTS
CONTENTS
BORANG PENYERAHAN THESIS APPROVAL SHEET
DEDICATION
ACKNOWLEDGEMENT ABSTRACT
ABSTRAK
TABLE OF CONTENT LIST OF APPENDIX
LIST OF FIGURE NOTATION
CHAPTER 1 1.1
1.2
CHAPTER 2 2.1
2.2
2.3
2.4
INTRODUCTION General
Objective
LITERATURE REVIEW General
Slope Stability
2.2.1 Slope Failure Soil Pressure
2.3.1 Rowe(1952)
2.3.2 Terzaghi & Peck(1967) 2.3.3 TchebotarioM 1973)
Stability of Supprted Exacavation 2.4.1 Ward(1955)
Page
ü
III
IV
V vi
vii
viii
xi
Iii xiv
1 I 2
3 3 5 7
10 10 13 16 18 20
viii
I
2.5
2.6
2.4.2 Bjerrum & Kirkerdam(1958) 21
Displacement around excavation 23
2.5.1 Caspe(1966) 23
2.5.2 Clough and Danby(1976) 24
2.5.3 Burland and Hancock(1977) 24
Embankment 27
2.6.1 Bergado(1994) 27
2.6.2 Hansbo(1987) 28
2.6.3 Furtensberg, Lechonicz and Wolski(1983) 29
2.6.4 Szymanski(1997) 33
CHAPTER 3 DESCRIPTION OF PLAXIS
3.1
3.2 3.3
3.4
3.5
General
3.1.1 Plaxis Version
3.1.2 Introductory Version 3.1.3 Professional Version Hardware Specification
Mesh Generation 3.3.1 Mesh block
3.3.2 Quadrilaterals 3.3.3 Triangles
3.3.4 Stress Points Feature Review
3.4.1 Interface Elements
3.4.2 Wall, Plates and Shells
35 35 36 39 39 39 40 40 41 41 42 44 44 44
3.4.3 Anchor Elements 44
3.4.4 Mohr Coulumb Model 45
Operation Scheme 45
3.5.1 Input data 45
3.5.2 Boundary Condition 47
3.5.3 Material Properties & others Input Data 47
Ix
CHAPTER 4 4.1
4.2 4.3 4.4 4.5
4.6
CHAPTER 5 5.1
5.2 5.3
5.4 5.5 5.6 5.7
CHAPTER 6 6.1
6.2
REFERENCES
APPENDIX
3.5.4 Groundwater Condition
3.5.5 Initial Mesh Configuration 3.5.6 Initial Stresses
3.5.7 Calculations
DESCRIPTION OF CASE General
Soil Properties Wall Properties
Anchor Element Properties Groundwater Condition
4.5.1 Initial Stresses Stage Of Construction
RESULTS AND DISCUSSION General
Deflection Of Sheet Pile walls
Bending Moment Of Sheet Pile Walls Shear Force
Mesh Deformation Soil Stress Levels Anchor Loads
CONCLUSIONS & RECOMMENDATIONS Conclusion
Recommendation
48 48 48 49
50 50 51 52 53 54 54 54
55 55 60 62 62 68 69 73
74 74 75
X
LIST OF APPENDIX
APPENDIX A Properties of soil type with temporary cut of constrution.
APPENDIX B APPENDIX C
APPENDIX D
APPENDIX E
APPENDIX F
APPENDIX G
Properties of meterials.
Graph 1.0, Displacement of sheet pile walls for every stage of Construction.
Graph 2.0, Moment of sheet pile walls for every stage of construction.
Graph 3.0, Shear force of sheet pile wall for every stage of contruction.
Contour of relative shear stress (tau/tau-max).
Contour of displacement increment for different height of sheet piles.
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XI
NOTATIONS
B= Width of Exacavation (m or ft).
C= Average cohesion of clay.
E, 4 = Normal Stiffness.
EI = Flexural Stiffness.
H= Depth of excavation.
Ka = Coefficient of active earth pressure.
Ko = Coefficient of lateral pressure.
M=A coefficient.
Nc = Coefficient depending on the dimensions of the excavation.
P= Surface surcharge
S= Undrained shear strength.
y= Bulk density of the soil
0=
Angle of vertical friction of the soil.910 = Initial Vertical Stress.
9, o = Initial Horizontal Stress.
XIV
CHAPTER ONE
INTRODUCTION
1.1 General
The term excavation and embankment includes a work on earthfill, cut and mixture of cut and fill (Kerisel, 1985). Construction work on site involved a work of excavation and embankment such as foundation, retaining walls, drainage, road etc.
There are few factor that should be considered before and during the construction of excavation such as types of support of excavation, types of soil, groundwater level, settlement and type of fill material
used. However, for construction of embankment common factor that should be considered is the stability against shear failure and settlement. The stresses can then be compared to the strength and thus directly used for stability calculation.
Although this project analyze parameter that could influence the
work of excavation and embankment a case study of Rotterdam
I
Tunnel was choosen in this project to study the behaviour of the excavation. This is due to the fact that embankment and excavation involved soil and rock, beside those item have a material with a variation of constitution as in its behaviour under various condition of environment and loads. So, by using PLAXIS were idle tool to solving any problem that facing during excavation.
1.2 Objective
The objective of the project are:
" To use PAXIS to simulate and study the effect of excavation consider with respect of the support with the different height of sheet piles or deep and types of struts (arrangement).
" To use PLAXIS to simulate and also study the movement of excavation soil and the anchor which are used to support the retaining structure during construction. The settlement at the top of the retaining structure and bottom heave are also study.
" To identify which the most suitable design for construction of retaining structure especially when it deal with different height of
sheet pile wall.
2
CHAPTER TWO
LITERATURE REVIEW
2.1 General
Excavation involved a removal of material and consequently causes a change in the state of stress in soil or rock beneath and beside the excavated space (Wolmer Fellemus, 1876). In as much as no material
can experience a change in stress without corresponding deformations, excavation is always associated with movements of the
adjacent ground surface.
Some soil will stand to considerable depths when cut vertically, although most will not. When vertical slopes slough out to a stable angle, large blocks of material may slide down into the excavation
work. Some temporary of slopes were need during the excavation which depends the types of soil .
Practically, there were two method that consider in excavation work;
" Bulk Excavation
The choice of plant for bulk excavation is large determined by the quantity and by the length of haul to the disposal point. Heavy machinery were use and it's also depend the type of soil by using it, for example; Backacter (backhoe), dragline and grab.
" Rock excavation
The use for explosive to break up the rock in advance of mechanical excavation is necessary in all but the weakest rocks such as weathered mudstone
, chalk and shales. However the use of explosive involves noise and vibration and the risk of annoyance to the public and possible damage to property.
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Figure 2.0 Shown about the excavation by using sheet pile to support the wall
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2.2 Slope stability
Three main considerations govern the determination of stable slopes for open excavation. The first of these, is the type of soil. The second is the length of time over which the excavation is required to remain open, and the third is the permissible degree of risk of slipping
Gravititional and seepage forces tends to cause instability in natural slopes, in slopes formed by excavation and in slopes of embankment.
When a slope is formed by excavation, the decrease in total stress result in changes in pore water pressure in the vicinity of the slope and particular, along a potential failure surface ( W. H Ting, 1987).
Many excavation are started with a vertical cut. Some soil will stand to considerable depths when cut vertically although most will not.
When vertical slopes slough off to a stable angle, long blocks of material may slide down into the excavation.
The angle at which soil can be expected to stand temporarily during excavation can be calculated. Some rough rule of thumb slope angle
are presented at Appendix A and figure 2.1
When the construction area is large , excavation walls maybe sloped
in lieu of providing structural support. Selection of a suitable slope
5
involves knowledge of the properties of the soil at the side and application of the principles of soil mechanics.
( W. L Schroeder & IS Diskenson, 1984).
The direct effect of water in a slope is obvious in connection with seepage, particularly out of slope which causes failure without necessarily being associated with a change in the soil strength. The increase in moisture content can allow immediate reduction in negative pore pressure, swelling on the soil, decrease in inter-granular pressure and loss of cohesive strength (Vail and Beattie, 1985).
6
I-17
Figure 2.1 Slope angle ß, degrees
2.2.1 Slope Failure
Slopes may fail because of the number of mechanisms, depending on the nature of the soil involved and the arrangement of natural earth materials at the site. A number of these mechanisms shown in Fig 2.2.
Three types of failure were identified which depend of soil type;
Rotational Slump, Translational and Slip.
7
Slopes failures occurs because forces tending to cause instability exceed those tending to resist it. Generally, the driving forces are represented by a component of soil weight down-slope and the resisting forces are represented by the soil strength acting in the opposite direction.
In any case, the factor of safety (FS) for the slope is expressed as the ratio of resisting moments to the driving forces or moments. When the factor of safety is I or less, the slope must fail. When the factor of safety exceeds 1, the slope theoretically stable. In designing cut slopes, the usual factor of safety required in between 1.3. and 1.5.
8
Fig. 2.2 Some slope failure mechanisms (a) Rotatioanal slump in homogeneous clay, (b) Translatioanal slide in cohesionless sand or
gravel, (c) Slip along plane of weakness.
9
2.3 Soil Pressure
Actually, for every excavation work have to considering the soil pressure. Soil is comprised of particles, large and small and it may be necessary to include as "soil" not only solid matter but also air and water.
The soil pressure also known as lateral earth pressure in undisturb soil deposit may considered as proportional to the vertical pressure. Soil behave as linearly elastic porous material which deforms with the change in the effective stress applied (Biot, 1941,1955 &1956).
2.3.1 Rowe (1952)
The author was using the flexibility method for design approach of sheet pile in sand. By assuming the that the anchor and subsoil yield approximately have same amount, such the wall will translate away
from the retained soil into the soil below the dredge level. This is the free earth support condition and the equations governing the pressure distribution on gravity walls apply.
Factored soil properties are used on the passive side and taking moments of the active and passive forces about the anchorage point gives an equation for the penetration depth D from which D is determined. Figure 2.3 below shown the moment reduction curves
10
obtained by the author for a sheet - pile wall embedded in sand and retaining sand; a is the ratio of depth of dregde level to the total length H of the piles and p is the flexibility number defined by :
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Figure 2.3 Moment reduction curves for sheet -pile walls in sand (After Rome, 1952)
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