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UNIVERSITI PUTRA MALAYSIA

SHEAR STRENGTH CHARACTERISTICS AND MICROCRACK PATTERN OF GRANITE FROM POS SELIM, PERAK, MALAYSIA

NUR IRFAH MOHD PAUZI

T FK 2007 36



MASTER OF SCIENCE UNIVERSITI PUTRA MALAYSIA

2007


By


Thesis Submitted to the School of Graduate Studies, Universiti Putra Malaysia in Fulfilment of the Requirement for the Degree of Master of Science

May 2007

Abstract of thesis presented to the Senate of Universiti Putra Malaysia in fulfilment of the requirement for the degree of Master of Science.

SHEAR STRENGTH CHARACTERISTICS AND MICROCRACK PATTERN

OF GRANITE FROM POS SELIM, PERAK, MALAYSIA

By

NUR IRFAH BINTI MOHD PAUZI

May 2007

Chairman : Associate Professor Husaini bin Omar, PhD.

Faculty : Engineering

Granite bodies can fracture in various characteristic ways relative to the density of

fractures, the number of joints sets and their distribution, and the type of fractographic

features on fracture surfaces. Granite commonly involves complex composite

microcrack systems which are caused by different geologic processes under varying

condition. Microscopic studies of cracks under shear stress in granite samples have been

carried out using Robertson shear testing and Scanning Electron Microscope (SEM) to

study the shear strength parameters and their interaction between microcrack

propagation patterns. Shear strength parameters such as friction angle and cohesion,

Joint Roughness Coefficient (JRC) and Joint Compressive Strength (JCS) has been

studied on granite at Pos Selim area. Microcrack propagation patterns for granite at Pos

Selim has been proposed to be categorized into two type which are type A and type B.

Type A is microcrack propagation pattern for granite grade II and type B is microcrack

propagation pattern for granite grade III. Griffith theory states that fracture material is

caused by stress concentration, causing the crack to propagate and ultimately

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contributing to microscopic failure of the material. The result show that type A and type

B microcrack propagation patterns do comply with Griffith theory. Type A microcrack

propagation pattern does not lead to failure and consists of minor crack surface. This is

because type A material has higher strength compared to type B. Type B material show

microcrack pattern that propagates from the left side of the sample leading towards the

right side of the sample which caused failure of the material. The relationship between

the microcrack pattern and the shear strength parameters proves that an increase in shear

stress and normal stress would result in increase of microcrack area. Therefore, the

knowledge from these studies show that the understanding in microcrack propagation

patterns can improve our understanding of damaging process and failure of intact rock.

Abstrak tesis yang dikemukakan kepada Senat Universiti Putra Malaysia sebagai memenuhi keperluan untuk ijazah Master Sains

CIRI-CIRI KEKUATAN RICIH DAN CORAK REKAHAN MIKRO PADA

BATUAN GRANIT DARI POS SELIM, PERAK, MALAYSIA

Oleh

NUR IRFAH BINTI MOHD PAUZI

Mei 2007 Pengerusi : Professor Madya Husaini bin Omar, PhD

Fakulti : Kejuruteraan

Batuan granit boleh merekah dengan pelbagai cara bergantung kepada ketumpatan

rekahan, jumlah set-set belahan dan taburannya, dan ciri-ciri permukaan fraktografiknya

pada permukaan retak. Lazimnya, granit mempunyai proses komposit yang kompleks

pada sistem retakan mikronya kerana perbezaan proses geologi yang berlaku disebabkan

oleh pelbagai situasi. Kajian retakan mikro yang disebabkan oleh tekanan ricih telah

diuji dengan menggunakan ujian kekuatan ricih Robertson dan mikroskop pengimbas

elektron pada sampel granit untuk menguji parameter-parameter kekuatan ricih dan

kaitannya dengan bentuk retakan mikro. Parameter-parameter kekuatan ricih ini

termasuklah sudut geseran dan kejeleketan, pemalar kasar rekahan (JRC) dan kekuatan

mampatan rekahan (JCS) yang dikaji pada batuan granit di kawasan Pos Selim. Bentuk

retakan mikro telah dicadangkan untuk dibahagikan kepada dua kategori iaitu jenis A

dan jenis B. Jenis A ialah bentuk retakan mikro untuk granit gred II and jenis B ialah

bentuk rekahan mikro untuk granit gred III. Teori Griffith telah menyatakan bahawa

retakan pada bahan adalah disebabkan oleh konsentrasi tekanan, yang boleh

menyebabkan retakan menular dan akhirnya terbentuklah retakan mikroskopik pada

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sampel. Hasil daripada kajian menunjukkan jenis A dan jenis B memenuhi kehendak

teori Griffith. Retakan mikro Jenis A tidak mengalami kegagalan dan terdiri daripada

permukaan retakan yang minor. Ini adalah kerana jenis A mempunyai kekuatan batuan

yang lebih tinggi berbanding dengan jenis B. Retakan mikro pada bahan jenis B

menunjukkan retakan menular daripada satu sudut tepi kepada satu sudut tepi yang lain

dan memecahkan sampel kepada dua bahagian. Hubungan di antara bentuk retakan

mikro dengan parameter kekuatan ricih menunjukkan dengan meningkatnya tekanan

ricih dan tekanan normal akan menyebabkan peningkatan pada keluasan bentuk retakan

mikro. Dengan ini, pengetahuan daripada kajian ini menunjukkan bahawa kajian retakan

mikro boleh menambahkan lagi kefahaman kita dalam mengkaji proses kerosakan dan

kegagalan pada batuan.

ACKNOWLEDGEMENTS

First of all, thanks to God, the most Gracious and most Merciful

I wish to acknowledge my supervisors, Associate Professor Dr. Husaini Omar,

Professor Bujang Kim Huat and Mr. Shukri Maail for their supervision and

encouragement. The patience and contribution of my beloved husband, Mr. Mohd

Shahril Mat Radhi, who is constantly giving guidance and motivation, is highly

appreciated. I wish to thank my father, Mr. Mohd Pauzi Abdul Hamid and my mother,

Dr. Nik Nawal Nik Mohd Adeeb who are constantly praying for my success, health and

wealth.

I also extended my acknowledgement to the following: Mr. Ahmad Zaidi (Principal

Geologist of Jabatan Mineral & Geosains) and Mr. Ferdaus Ahmad (Geologist Officer

of Jabatan Mineral & Geosains), Ir. Dr. Mohd Asbi Othman (Director of Mohd Asbi

and Associate), Ir. Saaidin (Director of ZMS Consultant), Mr. Ayob Mat Noor

(Engineer of Terratech Consultant), for their support.

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I certify that an Examination Committee has met on 9th May 2007 to conduct the final examination of Nur Irfah Mohd Pauzi on her Master of Science thesis entitled “Shear Strength Characteristics and Microcrack Pattern of Granite from Pos Selim, Perak, Malaysia” in accordance with Universiti Pertanian Malaysia (Higher Degree) Act 1980 and Universiti Pertanian Malaysia (Higher Degree) Regulations 1981. The Committee recommends that the candidate be awarded the relevant degree. Members of the Examination Committee were as follows: Mohd Salleh b. Jaafar, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Jamaloddin b. Noorzaei, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Azlan b. Abdul Aziz, Lecturer Faculty of Engineering Universiti Putra Malaysia (Internal Examiner) Faisal b. Haji Ali, PhD Professor Civil Engineering Department Faculty of Engineering Universiti Malaya (External Examiner)

___________________________________ HASANAH MOHD GHAZALI, PhD. Professor/Deputy Dean School of Graduate Studies Universiti Putra Malaysia Date: 3 August 2007

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This thesis submitted to the Senate of Universiti Putra Malaysia and has been accepted as fulfilment of the requirement for the degree of Master of Science. The members of the Supervisory Committee are as follows: Husaini Omar, PhD Associate Professor Faculty of Engineering Universiti Putra Malaysia (Chairman) Bujang Kim Huat, PhD Professor Faculty of Engineering Universiti Putra Malaysia (Member) Shukri Maail Lecturer Faculty of Engineering Universiti Putra Malaysia (Member) ___________________________ AINI IDERIS, PhD. Professor/Dean School of Graduate Studies Universiti Putra Malaysia Date: 9 August 2007

DECLARATION

I hereby declare that the thesis is based on my original work except for quotations and citation which have been duly acknowledged. I also declare that it has not been previously or concurrently submitted for any other degree at UPM or other institutions.

________________________


Date: 25 June 2007

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TABLE OF CONTENTS

Page ABSTRACT ii ABSTRAK iv ACKNOWLEDGEMENTS vi APPROVAL vii DECLARATION ix LIST OF TABLES xii LIST OF FIGURES xiv LIST OF ABBREVIATIONS xvii

CHAPTER 1 INTRODUCTION 1

1.1 Background 1 1.2 Problem Statement 4 1.3 Research Aims and Objectives 5 1.4 Scope and Limitation 6 1.5 Expected Outcome of the Research 6

2 LITERATURE REVIEW 7

2.1 Introduction 7 2.2 Shear Strength Parameters 8

2.2.1Friction Angle and Cohesion 9 2.2.2 Joint Roughness Coefficient (JRC) 12 2.2.3 Joint Compressive Strength (JCS) 16 2.3 Microcrack Propagation 17 2.3.1 Process of Microcrack Propagation 18 2.3.2 Griffith Theory 19

2.3.3 Microcrack Loading Modes 22 2.3.4 Types of Microcrack 25 2.3.5 Microcrack Mechanism in Granitic Rock 27

2.4 Case Study – Rock Shear Strength Determination 28

3 MATERIALS AND METHODS 30

3.1 Introduction 30 3.2 The Methodology of the Study 31 3.3 Field Data Collection 33 3.4 Surface Texture Analysis 43

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3.5 Shear Tests 43 3.5.1 Shear Tests Equipment 44 3.5.2 Preparation of Samples 48 3.5.3 Testing Procedure 50 3.6 Scanning Electron Microscope (SEM) Image Analysis 56 3.6.1 SEM Testing Equipment 56 3.6.2 Preparation of Samples 57 3.6.3 SEM Testing Procedure 59 3.7 The Establishment of Shear Strength Parameters of Granite 62 in Pos Selim Area 3.8 Proposed Microcrack Pattern of Granite in Pos Selim Area 63

3.9 Relationship between Microcrack Pattern and the Shear 64 Strength Parameters of Granite

4 RESULTS AND DISCUSSIONS 65

4.1 Introduction 65 4.2 Field Data Collection 66

4.2.1 Geological Setting 66 4.2.2 Granite Samples 67 4.3 Surface Texture Analysis 68

4.4 Shear Strength Parameters of Pos Selim Granite 72 4.4.1 Shear Stress versus Shear Displacement 73 4.4.2 Shear Stress versus Normal Stress 80 4.4.3 Friction Angle and Cohesion 83 4.4.4 Joint Roughness Coefficient (JRC) 84 4.4.5 Joint Compressive Strength and Basic Friction 87

4.5 Microcrack Pattern Analysis 92 4.5.1 Pre-Shear 92 4.5.2 Post-Shear 96 4.5.3 Microcrack Pattern 101 4.6 Microcrack Pattern of Granite at Pos Selim Area 120 4.6.1 Microcrack Pattern Type A 120 4.6.2 Microcrack Pattern Type B 124 4.7 Relationship between Microcrack Pattern and the 127 Shear Strength Parameters 4.8 Conclusion 134 5 CONCLUSIONS AND RECOMMENDATIONS 140

5.1 Major Findings 142 5.2 Future Studies 143

REFERENCES 144 APPENDICES 151 BIODATA OF THE AUTHOR 219

LIST OF TABLES

Table Page

2.1 Some basic friction angles of granite rock reported by different researchers 12

2.2 Description of joint type and corresponding range of JRC 14

2.3 Rock Material Strength 17

3.1 Weathering grade classification system for granite and volcanic rocks 40

4.1 Surface Texture of Sample Grade II 69

4.2 Surface Texture of Sample Grade III 71

4.3 Shear stress and normal stress at failure point 81

4.4 Friction Angle and Cohesion values 83

4.5 Friction Angle and Cohesion based on Slope Location 84

4.6 Joint Roughness Coefficient for Pre-Shear and Post-Shear 86

4.7 Schmidt hammer value 87

4.8 JCS and basic friction angle data 87

4.9 SEM analysis data (Sample S1 to S5 in Grade III) 114



4.12 SEM analysis data (Sample S21 to S25 in Grade II) 117



4.15 Summary the Result of Shear Analysis 135

4.16 Some basic friction angles of granite rock reported by different researchers 135

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4.17 Microcrack pattern analysis and the characteristic of shear parameters 137

LIST OF FIGURES

Figure Page

2.1 Shear stress versus normal stress curve showing the friction angle 9 and cohesion

2.2 The plane discontinuity surface is inclined at angle i 11

2.3 Typical discontinuity roughness profiles and associated JRC values 15

2.4 Schematic diagram illustrating the process of fracture. (a) An initial crack of size Co. (b) Crack propagation under the influence of a tensile load P; the crack reaches a critical size Cc and the part becomes overloaded because of the corresponding reduction in cross-sectional area supporting the load. (c) Final separation due to an overloading condition. 19

2.5 Stress distribution around an elliptical hole in a plate composed of a homogeneous material 20

2.6 Basic modes of fracture (a) Mode I (b) Mode II (c) Mode III. The arrows

indicate the direction of displacement of crack surfaces. 23 2.7 Schematic illustrating the macroscopic appearance of fracture surfaces (a)

Square (b) Slant (single crystal) (c) Slant (polycrystalline aggregate) (d) Mixture of square and slant. 25

2.8 Transgranular and intergranular fracture of rock 26

3.1 The methodology of the study 32

3.2 Geological mapping of the peninsular Malaysia, which shows the location of igneous rocks 36

3.3 Type of texture (a) phaneritic texture, (b) porphyritic-phaneritic texture, (c) aphanitic texture, (d) porphyritic-aphanitic texture, (e) glassy texture and (f) fragmental texture 38

3.4 Typical weathering profile of granite at Karak Highway 41

3.5 The process of sample collection, (a) the coring machine, (b) the process of insertion the coring in three stages, (c) the coring is done on rock surface and (d) sample taken out from the coring machine. 42

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3.6 The shear box apparatus (a) upper box and (b) lower box 45

3.7 Hydraulic pump (a) measuring the shear pressure (b) measuring the normal load 46

3.8 Dial gauge to measure shear displacement 47

3.9 Drawing of shear machine showing the position of the specimen and the shear surface 48

3.10 The apparatus needed for mixing the gypsum plaster. 49 3.11 Shear specimen preparations, (i) the casting that have already set are

stripped from the mould (ii) the casting is transferred to shear machine. 51

3.12 The value of cohesion is the initial value of the graph normal stress versus shear stress 53

3.13 RocData 3.0 Software Analysis 54

3.14 Schematic diagram of RocData Analysis 55

3.15 SEM equipment used for testing 57

3.16 Aluminum stub used for the testing 58

3.17 Two experiments involved in the testing of microcrack pattern 59

3.18 Crack measurement on the SEM testing 61

3.19 The sheared surface areas are round in circle showing 55% of sheared surface. 62

4.1 Location of Pos Selim Highway, Perak 67

4.2 Shear Stress versus Shear Displacement for sample S1 to S5 74





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4.10 Normal Stress versus Shear Stress (S1 to S40) 82

4.11 Joint Roughness Coefficient (JRC) obtained in RocData software 85

4.12 Relationship between Schmidt hammer value and the JCS values 88

4.13 Typical Analysis of shear strength using RocData for Grade III 90

4.14 Typical Analysis of shear strength using RocData for Grade II 91

4.15 Pre-shear SEM microcrack fracture of grade II (a) Sample A (b) Sample B, (c) Sample C, (d) Sample D, (e) Sample E 93

4.16 Pre-shear SEM microcrack fracture of grade III (a) Sample F (b) Sample G, (c) Sample H, (d) Sample I, (e) Sample J 95

4.17 Post-shear SEM microcrack fracture of grade II (a) Sample A (b) Sample B, (c) Sample C, (d) Sample D, (e) Sample E 98

4.18 Post-shear SEM microcrack fracture of grade III (a) Sample F

(b) Sample G, (c) Sample H, (d) Sample I, (e) Sample J 100

4.19 Percentage of sheared and crack length for grade III 103

4.20 Percentage of sheared and crack length for grade II 104

4.21 SEM testing during pre-shear and post-shear for sample grade III 108

4.22 SEM testing during pre-shear and post-shear for sample grade II 110

4.23 Microcrack pattern Type A 121

4.24 Microcrack pattern Type B 125

4.25 Percentage of Sheared Surface vs. Normal Load at Post Shear Stage 129

4.26 Shear Stress versus Area of microcrack for Type A 130 4.27 Shear Stress versus Area of microcrack for Type B 131

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4.28 Normal Stress versus Area of microcrack for Type A 132 4.29 Normal Stress versus Area of microcrack for Type B 133

LIST OF ABBREVIATIONS c cohesion

CH Chainage

FOS Factor of safety

Ft feet

H, h Height

i Roughness Angle

inch inches

JCS Joint Compressive Strength

JRC Joints Roughness Coefficient

km kilometers

kN kilo Newton

L, l Length

MPa Mega Pascal

m meters

mm millimeters

SEM Scanning Electron Microscope

w width

τ shear stress

σn normal stress

α Slope angle

Φb Basic friction angle

φ Angle of internal friction

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CHAPTER 1

INTRODUCTION

1.1 Background

Granite is characterized by microstructures including microcrack and microcavities

whose evolution and interaction under stress called the micro-damage process that

determine the macroscopic mechanical response. Granite commonly involves complex

composite microcrack systems which are caused by different geologic processes under

varying conditions (Kranz, 1983).

Granite bodies can fracture in various characteristic ways relative to the density of

fractures, the number of joints sets and their distribution and the types of fractographic

features on fracture surfaces. These microcrack fracture studies are of increasing

interest in geophysics and engineering related to underground radioactive waste

repositories. Physical properties of rocks are not only affected by the constituent

minerals and their preferred orientation, but also by the microcracks (Ahrens and Rubin,

1993; Shen et al, 1995; Li et al, 1998; Wong and Chau, 1998; Eberhardt et al, 1999, and

David et al, 1999). Since microcracks play an important role in physical properties of

rock, microcracks are also studied to know its relation with the engineering properties

such as the shear strength parameters that could affect the stability of slopes.

Many researches [Hoek and Bray (1981), Barton (1971) and Rengers (1971), Barton

(1973) Barton and Choubey (1977) Zainuddin et al (2001), Lan et al (2003), Komoo et

al., 2004) and Jiang et al (2006)] have done studies on the shear strength parameters of

rock. However their rock strength parameters data are based on the rock from their

respective countries. It is not known whether their rock has the same shear strength

parameters as the rock in Malaysia. To ensure the safety of cut slopes in Malaysia, there

is a dire need to establish Malaysian data of shear strength parameters of rock. This

research is carried out to fulfill this need. The outcome from this research will provide

data on the shear strength parameters of Malaysian rock required by slope designers.

When analyzing the stability of a rock slope, there are three important factors that need

to be considered, namely the geometry of the rock mass behind the slope face, the shear

strength of potential failure surface and the groundwater flow in rock masses. The

determination of reliable shear strength values is a critical part of a slope design because

relatively small changes in shear strength can result in significant changes in the safe

height or angle of a slope. Thus, an appropriate choice of shear strength values depends

not only upon the availability of test data but also upon interpretation of these data in

the light of the behaviour of the rock mass. This research hopes to provide the reliable

shear strength data for Malaysian rock slope.

The stability of slopes varies with the inclination of discontinuity surfaces. Examples of

discontinuity surface are faults, joint and bedding planes which are found within the

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rock mass. When these discontinuities are vertical or horizontal, simple sliding cannot

take place and the slope failure will involve fracture of intact blocks of rock as well as

movement along some of the discontinuities. However, if the rock mass contains

discontinuities surface dipping towards the slope face at angles of between 30 degrees

to 70 degrees, simple sliding can occur and the stability of this slope is significantly

unstable compared to those slopes which contain horizontal and vertical discontinuities.

Clearly, it can be said that the presence or absence of discontinuities has a very

important influence upon the stability of rock slopes and the detection of these

geological features are the most critical part of stability investigation. After recognizing

the discontinuities on slope, the material properties such as friction angle and cohesion

are the next most relevant properties in slope stability analysis. The friction angle and

cohesion are determined in this study. Other than that the Joint Roughness Coefficient

and Joint Compressive Strength are also determined in this study. These parameters are

the main parameters to be used in the design of cut rock slope.

Shear stress mechanisms on the saw-cut surface which produce the crack surfaces after

the shear stress is applied are studied. These crack surfaces may have relation to the

shear strength parameters and contribute to the reliability of the design of the cut slope.

The presence of crack surfaces, porosity and fractured characteristic which are

considered as microscopic flaws can be observed microscopically with a Scanning

Electron Microscope (SEM). SEM has become available as a commercial instrument

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with a capability of imaging surface topography and morphology with unprecedented

advantage of depth of field and a capability for studying any surface in its original,

unaltered surface (Murr, 1991).

Thus, to investigate the microcrack propagation patterns and the shear strength

parameters, SEM has been used as a tool. The microcrack pattern before and after the

shear test is observed using SEM. The microcrack pattern that contains physical

constituent of rock has been studied in detail to relate it with the shear strength

parameters which are important for the analysis of slope stability. The knowledge from

this studies show that the understanding in microcrack can improve our understanding

of damaging process and failure of intact rock, and to prove that microcrack pattern

does also contribute to the shear strength characteristics.

1.2 Problem Statement

Shear strength parameters such as friction angle and cohesion are the main parameters

studied in this research. The reliability of this data is very important since the

parameters affect the design of slope angle and height. Currently, the design shear

parameters are assumed by the slope designer. This research hopes to give the range of

data for the slope designer to use as a guide when selecting the friction angle and

cohesion for the design of cut rock slopes in Malaysia.

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In this research, granitic core samples tested. The two experiments done in this study

were shear strength test and the microscopic fracture test. The shear strength test was

carried out to obtain the shear strength parameters data and the microscopic fracture test

was carried out to determine the crack fracture surface on sheared core sample using

Scanning Electron Microscope (SEM). The SEM image would give the fracture

characteristic and crack propagation on granitic rock. Then, this image was analyzed to

obtain a microcrack propagation pattern analysis which can be used for fracture

mechanics studies that must comply with Griffith theory of crack propagation.

1.3 Research Aim and Objectives

The main aim of this research is to investigate the shear strength parameters and its

microcrack pattern on granite in Pos Selim, Perak. The objectives of the research are:-

1. To determine the shear strength parameters such as friction angle, cohesion,

Joint Roughness Coefficient (JRC) and Joint Compressive Strength (JCS) of

granitic rock

2. To study and analyze the microscopic crack and fracture using Scanning

Electron Microscope

3. To propose the microcrack pattern of granite in Pos Selim area

4. To study the relationship between microcrack pattern and the shear strength

parameters of granite at Pos Selim area

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