the effectiveness of geosynthetic to prevent …kerja-kerja membuat cerun di lereng4ereng bukit...

THE EFFECTIVENESS OF GEOSYNTHETIC TO PREVENT SLOPE EROSION

I.

MUHAMAD IQMAL BIN MUHAMAD SHAH

AA07076

A Final Year Project submitted in partial fulfillment of the requirements for the award of

the degree of Bachelor of Civil Engineering

Faculty of Civil Engineering & Earth Resources

Universiti Malaysia Pahang

DECEMBER 2010

ABSTRACT

Slope failure or landslide always related to the slope works at the hilly area. One

of the factors that contribute to this problem when slope surface is exposes to the rainfall

or surface run-off that eroded particle from slope surface. Suitable protected layer and

types of vegetation is important in this final year project. This final year project was

carried out to determine the actual value of sedimentation when using protected layer

compared to unprotected layer or bare control slope, also carried out the soil

classification at the case study. Geogrid were selected to be used in this study and two

types of grass were selected as earth cover is Signal grass and Japanese millet. From the

shear strength test of soil at Bukit Gambang, the average of shear strength is 183.17 kPa

with angle of friction 37.1°. From the soil classification test, this soil is sand soil with

absence of fine gravel and little silt and clay. To ensure the successfully of this study,

four (4) slope model were develop to determine the sedimentation value of the slope

surface. Actual values of sedimentation were determined by using total suspended solid

method. This study conclude that slope surface that contain Japanese millet not effective

either control or protected slope model. Slope surface that protected with Geogrid shows

effectiveness where can reduce sedimentation up to 6.98x lO g/mL per m 2. Side

analysis form this study shows that Signal grass have effectiveness to protect slope

surface by reducing 2.72x10 3 g/mL per m2 sedimentation. The usage of Geogrid with

Signal grass totally shows the effectiveness to solve slope surface erosion problem that

can reduce sedimentation up to 3.86x1(1 3 g/mL per m2.

V

ABSTRAX

Kerja-kerja membuat cerun di lereng4ereng bukit sentiasa dikaitkan dengan

punca kegagalan cerun. Salah satu faktor yang menyumbang kepada ketidakstabilan

cerun adalah permukaan cerun yang terdedah dengan air yang menyebabkan hakisan

permukaan cerun. Kajian terhadap lapisan dan tanaman tutup bumi menjadi perkara

penting didalam kajian projek sarjana muda mi. Tujuan kajian mi dijalankan adalah

untuk mendapatkan nilai sebenar hakisan dan membezakan dengan permukaan cerun

yang tidak diberi perlindungan serta mengklasifikasikan jenis tanah di tapak kajian.

Lapisan yang digunakan didalam kajian mi ialah lapisan geogrid dan terdapat dua jenis

tanaman tutup bumi yang telah dikenal pasti sesuai digunakan iaitu Signal grass dan

Japanese millet. Ujian kekuatan ricih tanah di Bukit Gambang mendapati purata

kekuatan ricih tanah ialah 183.17 kPa dengan satah kegagalan sebanyak 37.1°. Dari ujian

pengekiasan tanah, tanah mi dikelaskan sebagai tanah pasir yang mengandungi batu

kelikir halus, sedikit kelodak dan tanah hat. Bagi memastikan kajian mi berjaya, empat

(4) buah model cerun dibina khas untuk mendapatkan niiai hakisan terhadap permukaan

cerun tersebut. Nilai sebenar hakisan dapat ditentukan dengan rnenggunakan kaedah

pepejal terampai. Kesimpulan kajian mi mendapati permukaan cerun yang menggunakan

rumput Japanese millet tidak berkesan samada dengan Geogrid atau tidak. Permukaan

cerun yang dilindungi dengan Geogrid adalah lebih baik dengan mengurangkan kesan

hakisan sebanyak 6.98x104 g/mL per m2. Kajian sehingan mendapati Signal grass juga

mempunyai keberkesanan dengan mengurangkan hakisan sebanyak 2.72x10 3 g/mL per

M2 . Penggunaan Geogrid dengan Signal grass sememangnya berkesan bagi menangani

masalah hakisan permukaan cerun dengan mengurangkan hakisan sebanyak 3.86x103

gImL per m2.

A

TABLE OF CONTENTS

CHAPTER TITLE PAGE

TITLE PAGE i

DECLARATION

DEDICATION iii

ACKNOWLEDGEMENT iv

ABSTRACT v

ABSTRAK vi

TABLE OF CONTENTS vii

LIST OF TABLES xii.

LIST OF FIGURES xiii

LIST OF SYMBOLS xvi

LIST OF APPENDICES xviii

CHAPTER 1 INTRODUCTION

1.1 Introduction 1

1.2 Problem statements 4

1.3 Objectives 6

1.4 Scope of works 6

1.5 Significant of study 10

VI'

CHAPTER 2 LITERITURE REVIEW

2.1 Introduction 11

2.2 Type of soil 12

2.2.1 Cohesive soils 13

2.2.2 Cohesionless soil 14

2.3 Particle size and gradation analysis 15 2.4 Soil classification 16

2.4.1 Unified Soil Classification System (USCS) 17

2.5 Slope vegetation 19

2.5.1 Function of vegetation 19

2.6 Slope 21

2.6.1 Types of slope 21

2.6.1.1 Finite slope 22

2.6.1.2 infinite slope 22

2.6.2 Landslide 23

2.6.3 Landslide chronology in Malaysia 23

2.6.4 Types of landslide 25

2.7 Rainfall 27

2.8 Use of Geosynthetic 28

2.8.1 Separation or stabilization 28

2.8.2 Drainage 29

2.8.3 Erosion control 29

2.8.4 Reinforcement 30

2.9 Woven Geosynthetic 30

2.9.1 Geogrid 30

2.9.2 Geoweb 31

viii

CHAPTER 3 METHODOLOGY

3.1 General 32

3.2 Preliminary research 33

3.3 Preparation of slope model 35

3.4 Laboratory testing 36

3.4.1 Soil classification 36

3.4.2 Particle size distribution 37

3.4.3 Sieve analysis test 37

3.4.4 Particle size analyzer 38

3.4.5 Moisture content 39

3.4.6 Liquid limit and plastic limit test 40

3.4.7 Specific gravity 42

3.4.8 Standard proctor test 43

3.4.9 Undrained Unconsolidated Shear Strength 44

3.4.9.1 Triaxial specimen 46

3.4.9.2 Undrained Unconsolidated test 46

3.5 Preparation of soil sample 47

3.6 Rainfall rate test 48

3.7 Sedimentation test 49

3.7.1 Total Suspended Solid 49

3.8 Report writing 50

CHAPTER 4 RESULT AND DISCUSSION

4.1 Introduction 51

4.2 Natural moisture content 52

4.3 Specific gravity 52

4.4 Particle size distribution 53

4.4.1 Result for soil sample at Bukit Gambang 54

lx

4.4. 1.1 Mechanical sieve analysis result 54

4.4.1.2 Particle size analyzer 55

4.5 Standard proctor test 56

4.6 Atterberg limit 57

4.7 Shear strength test result 59

4.8 Undrained shear strength classification 65

4.9 Rainfall rate test 65

4.10 Summary of soil classification 66

4.11 Total suspended solid result test 66

4.11.1 Japanese millet grass for control model 67

4.11.2 Signal grass with for control model 73

4.11.3 Japanese millet grass with Geogrid 79

4.11 .4 Signal grass with Geogrid 85

4.12 Erosion rate classification

4.12.1 Japanese millet protected model VS Japanese 91

millet control model

4.12.2 Signal grass protected model VS Signal grass 93

control model

4.12.3 Signal grass control model VS Japanese millet 95

control model

4.12.4 Signal grass protected model VS Japanese millet 97

protected model

4.13 Factor influence the experimental result 99

4.13.1 Disturbance of the soil sample 99

4.13.2 Handling equipment 100

4.13.3 Time constraint 100

4.13.4 Slope model not evenly leveled 101

4.13.5 Unsuitable rainfall sprinkler 101

4.13.6 Geogrid installation 101

x

CHAPTER 5 CONCLUSIONS AND RECOMMENDATION

5.1 Conclusions 102

5.2 Recommendation 104

REFERENCES 106

APPENDICES A-E 109

xi

LIST OF TABLES

TABLE NO. TITLE

PAGE

XII

2.1 USCS classification system

3.1 Typical laboratory testing and their method

4.1 Moisture content result

4.2 Specific gravity

4.3 Particle size percentage

4.4 Plastic limit result

4.5 Atterberg limit result

4.6 Shear strength parameters

4.7 Result undrained shear strength classification

4.8 Comparison between control and protected model with

Japanese millet grass

4.9 Comparison between control and protected model with

Signal grass

4.10 Comparison between Signal grass and Japanese millet grass

in control model

4.11 Comparison between Signal grass and Japanese millet grass

in protected model

18

36

52

53

54

58

58

60

65

91

93

95

97

LIST OF FIGURES

FIGURE NO. TITLE PAGE

1.1 Pacific ring of fire at equator line 3

1.2 Signal grass in specimen box 7

1.3 Japanese millet grass in specimen box 7

1.4 Slope surface in specimen box 8

1.5 Geogrid KG 60/60 8

1.6 Slope model with rain simulator 9

2.1 Landslide at MRSM Bentong 11

2.2 Semi log graph 16

2.3 Lateral, tap, and sinker roots of a woody root system 20

2.4 infinite slope 22

2.5 Landslide distribution in Malaysia for 1973 to 2007 24

2.6 Landslide distribution based on geomorphology form 1973 24

to 2007

2.7 Types of landslide 26

3.1 Flow process of methodology 34

3.2 Slope model 35

3.3 Set sieve analysis 38

3.4 Particle size analyzer 39

3.5 Cone penetration set 41

3.6 Apparatus for plastic limit test 41

3.7 Density bottle 42

3.8 Standard proctor test 43

3.9 Triaxial compression machine 44

xlii

Al V

3.10 Rain gauge 48

3.11 Total suspended solid standard apparatus 50

4.1 Particle size distribution curve for coarse grained of 55

soil sample at Bukit Gambang

4.2 Particle size distribution curve for fine grained of sample 56

4.3 Dry unit weight VS moisture content graph 57

4.4 Moisture content (%) versus penetration (mm) 58

4.5 Plasticity chart for laboratory classification of fine grained soils 59

4.6 (a) Triaxial compression test result for soil sample BH 1 60

4.6 (b) Triaxial compression test result for soil sample BR 2 62

4.6 (c) Triaxial compression test result for soil sample BR 3 63

4.7 Soil sample at BR 1 61

4.8 Soil sample at BR 2 63

4.9 Soil sample at BH 3 64

4.10 Graph of erosion rate for control model with Japanese millet 67

grass (00)


grass (10°)


grass (20°)

4.13 Graph of erosion rate for control mode! with Japanese millet 70

grass (30°)


grass (400)

4.15 (a) Runoff water collected at 400 slope 72

4.15 b) Slope surface failures 72

4.16 Graph of erosion rate for control model with Signal grass (0) 73

4.17 Graph of erosion rate for control model with Signal grass (10 0) 74

4.18 Graph of erosion rate for control model with Signal grass (20 0) 75

4.19 Graph of erosion rate for control model with Signal grass (30°) 76

4.20 Graph of erosion .rate for control model with Signal grass (40) 77

4.21 Graph of erosion rate for control model with Signal grass (50) 78

4.22 Condition of soil when failed at 50° slope. 79

xv

4.23 Graph of erosion rate for protected model with Japanese millet 79

grass (0°)


grass (100)


grass (200)


grass (300)


grass (400)

4.28 Slope surface condition failed at 40° slope. 84

4.29 Graph of erosion rate for protected model with Signal 85

grass (0°)


grass (100)


grass (200)


grass (300)


grass (400)


grass (500)

4.35 Protected slope model VS control slope model using 92

Japanese millet grass

4.36 Protected slope model VS Control slope model using 94

Signal grass

4.37 Control slope model using Signal grass VS Control slope 96

model using Japanese millet grass

4.38 Protected slope model using Signal grass VS Protected slope 98

model using Japanese millet grass

LIST OF SYMBOLS

A - Area

BH - Bore hole

C - Cohesion

C. - Undrained shear strength

C' - Effective cohesion

C - Clay

CL - Low plastic clay

GCLs - Geosynthetic clay liners

Us - Specific gravity

IL - Liquidity index

Ip - Plasticity index

I - Rainfall intensity

LI - Liquidity index

LL - Liquid limit

M - Silt

P1 - Plasticity index

PL - Plastic limit

UU - Undrained unconsolidated

UV - Ultraviolet

OMC - Optimum moisture content

S - Sand

SP - Poorly sand

w - Natural moisture content

WL - Liquid limit

WP - Plastic limit

xv'

Ws - Shrinkage limit

Q - Flow rate

z - Depth

a - Stress

a' - Effective stress

03 - Confining pressure

av - Overburden pressure

P - Density

Y - Bulk unit weight

Ydzy - Dry unit weight

- Internal angle of friction

- Effective angle of friction

tf - Stress at failure

OF - Degree Fahrenheit

°C - Degree Celsius

0 - Degree

xvii

LIST OF APPENDICES

APPENDIX TITLE PAGE

A Natural Moisture Content and Specific Gravity 109

B Particle Size Distribution Result and Standard Proctor 112

Test Result

C Atterberg Limit Test Result 121

D Shear Strength Result 123

E Rainfall Rate Test Result and Erosion Rate Result 130

xviii

CHAPTER 1

INTRODUCTION

1.0 Introduction

Highlands's area is a beautiful place to serve as travel, entertainment or as a

residence for people who like beautiful scenery, fresh air and away from the bustling

city. Highland areas in Malaysia including Cameron Highland, Genting Highland,

Fraser's Hill and Bukit Tinggi often become tourist attractions from within and

outside the country. Nowadays, highland areas in Malaysia are becoming more

sought-after the settlers who want to open the forest highlands. With activities such

as the development is expected to increase revenue, but instead have happened.

Malaysia has received a drastic current modernization began early 80s, where

there are many infrastructure development ahead run in the city or village. Not

exempt development on high ground and the slope of the hill-slope. Since developing,

many buildings can be built higher and also due to modernization, many residential

areas built in the hills because of the fmancial status changes dramatically. At that

time and now, housing in the area of land represents a high status to the buyer, but

buyers are not realizing the danger living in hilly area.

IL

November 1993, Malaysia shocked by landslides against the Highland Tower

which has claimed iiiany lives. The event was a great impact for Malaysia where the

effects of modernization has been shown to respond to the community. Since the

incident, the government has taken various measures to prevent landslides from

happening again, but the result disappointed. Since 1993, there are many cases

follow-up occurred after the landslide and also involves death and property loss.

While Malaysia can be categorized as a country that is safe from natural

disasters such as earthquakes, hurricanes and tsunamis, but Malaysia is not free from

landslides caused by climatic conditions and form of the hilly terrain. Malaysia

generally has a mountainous terrain in the middle of the country from north Malaysia

to the west coast. Titiwangsa Mountains range is the oldest in Malaysia which there

are many hills around. Mountainous also is an obstacle to the transport system to get

to the eat coast and northern Malaysia. Normally the way to go to the north and the

east coast, the road were be built on the hillside of the work involves cutting and trim

hill.

Malaysia's position is located in the middle of the equator line to receive hot

and humid weather throughout the year also located in a circle of Pacific Ring of Fire

that shows in Figure I.I. A climatic condition such as this is a major contributor to

landslides where the weathering process that occurs at very high line is the equator.

Malaysia also received high rainfall throughout the year starting from early October

until late January next year because of changes in the northeast monsoon winds.

Even though Malaysia is safe from earth quake, but Malaysia still can have the effect

form that activity and there is still no evident that says Malaysia are not suffer from

earth quake activity or massive movement of earth crust.

Figure 1.1: Pacific ring of fire at equator line

Source: Google earth

Water is a dangerous agent compared to wind, water not only can dissolve,

but it's scraping and drifting the soil particle. A part form factor land and climatic

conditions, there are several additional factors, such as less monitoring and

maintenance and the attitude not to know about the circumstances surrounding

highlands contribute to landslides. High land clearing activity not controlled can also

affect the geological origin of the region. Until now, there are many projects actively

carried out in the highlands, for example the construction of such roads in the

Simpang Pulai-Gua Musang-Lojing the recorded cases of concern.

Development in the hills that are not managed and controlled to give worst

impact to the country, when there is landslide occurs especially to the victim family

or community. Because landslides occur blinking of an eye and people who live on

high ground are not prepared, always is a victim of landslides. Effects of landslides

not only claimed lives and property, even harming the economy of the country as the

issue had to spend big to repair the destruction and damages. Also, there are some

people who suffer emotional disturbances because of past landslides.

4

1.2 Problem Statements

Development on high ground indeed invites the problem of landslides.

Generally, plateau areas are places where rain water catchment' s supplying water in

lowland areas. When the occurrence of development activities carried out, cutting of

forests in the highlands can disrupt the original ecology of the area. With activities

that also, it changed the pattern of water flow at the top of the hill. Time when it

rained, the water can easily infiltrate into the soil pores and loosen the bonds of soil

and the occurrence of landslides.

Landslides can occur in two ways, first by nature, and the second with the

man-made. However, as a result of man-made landslide that makes this worse

compare than nature. As an example, construction of roads in the hillside, Cut and

trim work involves hills and the result is there is a slope failure along the road.

Unfortunately, due to the progress of an area, work like this should be done.

However, it must be carefully planned and reviewed, also supervision and

maintenance that must be implemented consistently.

Slope failure is the main enemy really is water, because in Malaysia, the

rainfall for each year is quite high. Safe and well construction on slope can siphon

water out well from the slope. Certainly the increasingly steep slope, the speed of

water flow rate and increasingly dangerous conditions the slope. With the right

techniques must be adopted when the design of a slope. Most of the problems of

landslides or other words slope failure occurred due to poor technique and lack of

maintenance. This is because of slope failure cannot be predicting when it happen

when and where, so the design of a slope should first ensure its effectiveness.

Pattern of slope failure are many ways, including erosion slope. When the

occurrence of erosion slopes, the mountain has been lost from the water layer of

defence. Thus, water is easy to infiltrate into the hills and help to collapse. The main

5

factor is the occurrence of slope erosion processes of weathering, where hot and cold

conditions cause cracks in the surface and rain which came down to help eliminate

the particle of the soil. For problems like this, usually require in-depth study to

determine where the appropriate conditions are used to prevent erosion problems on

the surface slope.

Normally, the surface slope erosion solved by providing a special layer to

prevent soil movement from top to bottom. To prevent the erosion rate is by planting

grass on the surface of the slope to slow water runoff in surface slope. Surface slope

maintenance is important to ensure the safety of slopes. This is because the surface

slope acts as a barrier from water absorbed into the surface. This is important,

because surface slopes are low maintenance compared to the costs when a landslide

occurrence. So on the surface treatment is indeed important to guarantee the safety of

slopes.

With the existence of problems such as this, a study should be conducted to

investigate the effectiveness of the layer to treat this slope erosion problem.

Consistent with the title of this study, expected a new discovery or improvement on

how to prevent this problem The appropriate parameters must be studied in order get

good results and thus solve the puzzle about this problem.

b

1.3 Objective

The objectives of this study are:

1. To determine the soil properties at the Bukit Gambang area.

2. To analyze the effectiveness of Geosynthetic due to different types of

vegetation.

1.4 Scope of works

Studies that were implemented are related to the slope erosion involving the

study of soil properties and methods to prevent erosion. To implement this study, the

study of slope should be done, but it is difficult for outside research takes a long time

and uncertain circumstances. As solutions, this study was implemented to model

slope outside, which is smaller but still similar to the conditions outside. To ensure•

the success of this study, there are three processes to be carried out, the first study the

situation of soil properties in Bukit Gambang. Second, develop four slope models as

tool for this study. Finally, is comparing the effectiveness of Geosynthetic layer

between protected and control model and also due to different types of vegetation.

To studying soil properties in Bukit Gambang, soil usually be taken at the

surface slope. This soil are taken in Eukit Gambang and then brought back to the

laboratory for more in-depth study for soil classification. For research that utilizes

Geosynthetic, there are four soil specimens should be develop, two of it is the control

model are fertilized with two different types of grass and the other two are protected

model which protect by Geosynthetic material also fertilized with two different types

of grass. All of the slope models were using the same soil that taken from Bukit

Gambang.

7

There is two types of grass were planted for this study, first is Signal grass

where it is low-growing decumbent perennial, with trailing stems that root at the

nodes. It forms a dense soil cover, with a canopy usually under 40 cm when grazed

and Figure 1.2 shows a photo of Signal grass. The second grass is ordinary corps

field grass that suitable to adapt in wet soils and requires no soil preparation or care

called Japanese Millet grass. Figure 1.3 shows a photo of Japanese Millet grass.

Figure 1.2: Signal grass in specimen box

Figure 1.3: Japanese millet grass in specimen box

8

Specimen box were develop specifically for this study and specimen box has

dimensions measure 500 mm wide x 1000 mm long x 356 mm high (1 foot). Figure

1.4 shows the illustration of the slope surface in specimen box. There are many types

of Geosynthetic, and Geogrid were used for this study. Geogrids is only one of

Geosynthetic material can let grass grows on it and there is a standard size in the

market. In this study, Geogrids with a biaxial strength of 60 kN/m horizontally and

60 kN/m vertically were used and Figure 1.5 shows a photo of Geogrids.

Figure 1.4: Slope surface in specimen box

\ -

;.

I .-

: -3

- -) .-)•_ .

Figure 1.5: Geogrids KG 60/60

9

Slope model were also developed specially for the purpose of this study, it is

used to replicate the original slope. Slope model are constructed with a dimension of

1000 mm length x 500 mm wide x 1000 mm high. Specimen box were placed on the

top of slope model, where the soil are tested with various slope angles. The top of the

slope model can be rotated until 500 maximum. Slope surface in specimen box were

rotate for every 100 each starting from 00 until 500. Therefore, the study required 6

types of angles of rotation and 24 data of the erosion rate were collected.

To study the erosion rate, rain simulators were constructed to resemble the

actual rain or other words to make the process of weathering with the actual situation.

This study is implemented in open areas and rainfall simulator were accordance with

Malaysia average heavy rainfall with intensity 83.3 mm/hr. Rainfall simulations were

carried out for 1 hour for each specimen at a certain slope angle. To determine the

rate of erosion, the water runoff are collected and determine using the total

suspended solid apparatus, to knowing the particles of the soil has been eroded every

hour. Figure 1.6 shows the slope model and rain simulator illustration.

DIA WJ2lrn

PVC pipe

Specimen Box

b,soorn

I LOOm

Guer(WarCollector) -"

Slope Model Frame

Figure 1.6: Slope model with rain simulator

the effectiveness of geosynthetic to prevent …kerja-kerja membuat cerun di lereng4ereng bukit...

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