NUMERICAL ANALYSIS OF EMBEDDED REINFORCED SOIL FOUNDATION ON TWO-LAYER SOIL SYSTEM

BY

NG KOK SHIEN SITI FATIMAH BINTI SADIKON

JUN2010

ii

SuratKami : 600-RMl/ST/DANA 5/3/Dst (15/2009) Tarikh : 13 Mac 2009

Ng Kok Shien Ketua Projek Fakulti Kejuruteraan Elektrik UiTM Cawangan Perlis Kampus Arau PetiSurat41 02600 Arau PERLIS

Tuan/Puan,

TAJUK PROJEK PENYELIDIKAN DANA KECEMERLANGAN: NUMERICAL STUDY OF EMBEDDED STRIP FOUNDATION ON GEOGRiD-REINFORCED SOUND

Dengan hormatnya perkara di atas adalah dirujuk.

Sukacita dimaklumkan Institut Pengurusan Penyelidikan (RMI) telah meluluskan cadangan penyelidikan yang telah dikemukakan oleh tuan/puan bertajuk di atas dengan syarat-syarat seperti berikut:

i. Tempoh projek penyelidikan ini ialah 1 tahun, iaitu bermula 15 Mac 2009 hingga 15 Mac 2010.

ii. Tuan/Puan dinasihatkan untuk membuat pembetulan proposal penyelidikan seperti yang dicadangkan oleh panel penilai (sila lihat lampiran penilai yang disertakanj

iii. Tuan/Puan dinasiharkan agar menambah bilangan ahli kumpulan penyelidikan.

iv. Kos yang diluluskan ialah sebanyak RM8,500.Q0 sahaja dalam (Kategori B). Tuan/Puan diminta mengemukakan proposal beserta bajet yang baru mengikut kos yang diluluskan sebelum tuan/puan memulakan projek penyelidikan tuan/puan.

v. Pembelian peralatan komputer/printer/PDA/alat multimedia adalah tidak dibenarkan.

vi. Semua pembelian bahan/peralatan adalah diminta agar tuan/puan mematuhi prosedur perbendaharaan di mana pembelian melebihi RM500.00 hendaklah mengemukakan sebutharga dan borang analisa harga.

Vii Pihak tuan/puan dikehendaki mengemukakan laporan prestasi secara ringkas pada setiap enam (6) bulan sepanjang tempoh penyelidikan tuan/puan berjalan.

olorsg rtaib Canseior (Penyel id ikan) : 603-5544 2094/2095 hag ian Penye l id i kan : 603 5544 2097/2091/5521 1462 hag ian Pe rund ingan : 603 5544 2100/2753/2092 hag ian Inovasi : 603-5544 2750/2747

Babagian Penerb i tan : 603-5521 1425/5544 2 /47 Bahag ian INFOREC : 603-5544 3097/2104/2098 Bahagian Sains: 603-5544 2098/5521 1463 Pejabat A m : 603 5544 2093/2101/2057/2559

Bahagian Pentadb i ran

Fax Un i t Kewangan Zon 1 7

603-5544 2090 603-5544 2096/ 603-5544 3404 603-5521 1386

ACKNOWLEDGEMENT

We wish to express our greatest appreciation and gratitude to all those who have helped us in completion and success of this research project. Without their help, this project is reaching nowhere.

Associate Professor Dr. Ahmad Redzuan Abdul Rahman (Director of UiTM Perlis)

Associate Professor Dr. Nik Ramli Nik Abdul Rashid (Campus Deputy Director PJI)

Syuzila Saad

PJI Staff

All our colleagues

And

To our beloved family for their patience, love and prayers.

VI

TABLE OF CONTENT

1.0 INTRODUCTION

1.1 Introduction 1

1.2 Research Background 2

1.3 Problem Statement 2

1.4 Research Objectives 3

1.5 Significance of Research 3

2.0 LITERATURE REVIEW

2.1 Geosynthethics 5

2.2 Functions and Application of Geosynthethics 6

2.3 Reinforced Soil Foundation (RSF) 7

2.3.1 Behaviour of Reinforced Soil Foundation 8

2.3.2 Analytical Study 11

2.3.3 Failure Mode of Reinforced Soil Foundation 13

2.4 Numerical Modeling of Reinforced Soil Foundation 16

3.0 SURFACE FOOTING

3.1 Introduction 17

3.2 Finite Element Analysis 17

3.3 Effect of Fill Depth and Friction Angle 22

3.4 Effect of Reinforcement Length 26

3.5 Effect of Reinforcement Stiffness 28

3.6 Effect of Clay Strength 29

3.7 Effect of Reinforcement Depth 30

3.8 Effect of Multi-layer Reinforcement 31

ABSTRACT

The behaviour of strip footings resting on subsoil consisting of a reinforced-granular

fill layer overlying a low bearing capacity soil was studied. Model setup was divided

into two: surface footing and embedded footing. A series of finite element (FE)

analysis were performed on a prototype model of both reinforced and unreinforced

foundations using FE commercial software PLAXIS. Updated mesh analysis based

on Updated Lagrangian formulation was adopted in this study. The purpose of this

study is to determine the effect of geosynthethics reinforcement on the ultimate

bearing capacity and settlement characteristics of the strip footing resting on a

granular fill - soft soil system. Particular emphasis is paid on the fill depth,

embedment depth, fill and soft soil strength, reinforcement stiffness and length, and

number of reinforcement layer. Besides, investigations on effects of laying

geosynthethics at the interface or into the layer of fill were studied. The method of

analysis was verified by comparison with analytical solution and previous study.

Based on the result, the reinforcing effect of two layer soil system is quantitatively

evaluated.

Xlll