THE STUDY OF THE COMPRESSIBILITY CHARACTERISTICS OF

SOFT SOIL IN SARAWAK

WONG SEAK YEO

This project is submitted in partial of fulfilment of

the requirements for the degree of Bachelor of Engineering with Honours

(Civil Engineering)

Faculty of Engineering

UNIVERSITI MALAYSIA SARAWAK

2005

Malaysia seperti yang termaktub di dalam AKTA RAHSIA RASMI 1972)

badan di mana penyelidikan dijalankan).

PKS/2001

UNIVERSITI MALAYSIA SARAWAK Kota Samarahan

fk

BORANG PENGESAHAN TESIS

Judul: The Study of The Compressibility Characteristics of Soft Soil in Sarawak __ _

___ ___________________________________________________________ _

______________________________________ ______________________ ___

Sesi Pengajian: 2001 - 2005

Saya WONG SEAK YEO__________________________ _________________

(HURUF BESAR)

mengaku membenarkan tesis * ini disimpan di Pusat Khidmat Maklumat Akademik, Universiti

Malaysia Sarawak dengan syarat-syarat kegunaan seperti berikut:

1. Tesis adalah hamilik Universiti Malaysia Sarawak.

2. Pusat Khidmat Maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan untuk

tujuan pengajian sahaja.

3. Membuat pengdigitan untuk membangunkan Pengkalan Data Kandungan Tempatan.

4. Pusat Khidmat maklumat Akademik, Universiti Malaysia Sarawak dibenarkan membuat salinan tesis ini

sebagai bahan pertukaran antara institusi pengajian tinggi.

5. ** Sila tandakan ( √ ) di kotak berkenaan

Sulit (Mengandungi maklumat yang berdarjah keselamatan atau kepentingan

1

Terhad (Mengandungi maklumat TERHAD yang telah ditentukan oleh organisasi/

1

Tidak Terhad

_____________________________________

(TANDATANGAN PENULIS) (TANDATANGAN PENYELIA)

Alamat tetap: Lot.2806, Jalan Bunga Raya, 1

Pasir Pinji, 1 1 Dr. Prabir Kumar Kolay

31650 Ipoh, Perak. 1 (Nama Penyelia)

Tarikh: Tarikh:

CATATAN * Tesis dimaksudkan sebagai tesis bagi Ijazah Doktor Falsafah, Sarjana dan Sarjana Muda

** Jika tesis ini SULIT atau TERHAD, sila lampirkan surat daripada pihak berkuasa/organisasi

berkenaan dengan menyatakan sekali sebab dan tempoh tesis ini perlu dikelaskan sebagai SULIT dan

TERHAD.

The Following Final Year Project Report:

Title : THE STUDY OF THE COMPRESSIBILITY

CHARACTERISTICS OF SOFT SOIL IN SARAWAK

Name of the author : WONG SEAK YEO

Matrix Number : 7477

Was read and certified by :

_____________________________ ____________

Dr. PRABIR KUMAR KOLAY Date

Project Supervisor

i

ACKNOWLEDGEMENTS

My sincerest appreciation must be absolutely to my supportive and helpful

supervisors; project supervisor, Dr. Prabir Kumar Kolay for his lofty visions, guidance,

supports and valuables knowledge during the project work.

The author also take this opportunity to thank the laboratory assistants of Civil

Engineering Program, Faculty of Engineering, Universiti Malaysia Sarawak and the

stuffs and laboratory assistants in Geospec for their supply of undisturbed soil samples

and use their lab facilities and assistance in carrying out the laboratory works during the

progression of the project.

A special thanks to my dearest friends Ong Chee Zen, Chong Kah Weng, Chai

Peng How, Kho Joo Tiong, Ong Khin Kiat, Adrian Fong Wei Yi, Dorothy Chai Sim

Yee, Onn Yin Wee and Ling Leh Shia who had been so helpful and supportive along

the implementation of the project.

The author is very grateful to his family, especially Madam Lee Tng Chu and

Mr. Wong Kow Chye, who always give their full supports and love. Your advice and

guidance will be always bear in mind.

Finally, I am deeply grateful to those individuals who involve directly and

indirectly all throughout the process of doing this project.

ii

ABSTRACT

The present study investigates the compressibility characteristics of soft

soil in Sarawak. To accomplish this study, eight undisturbed soil samples are

collected from different location i.e., Desa Senadin (Miri), Kampung Punang

(Lawas), Lundu (Kuching), Dan (Mukah), Sungai Miri (Miri) and Upper Lanang

(Batang Rajang). Different laboratory tests (moisture content, Atterberg limit,

specific gravity, grain size analysis, and consolidation) have been conducted on

these soil samples. The results reveal that the value of co-efficient of volume

change, mv for all the soil samples is gradually decreasing with the increase of

higher-pressure ranges but the co-efficient of consolidation, cv for all the samples

tested do not follow any specific trend with the increase of pressure. The

compression index, Cc values calculated from e-log P graph and formula ( Cc =

0.009 × (wL-10) ) are correlated with the values of plasticity index (PI).

iii

ABSTRAK

Kajian ini mengkaji tentang ciri-ciri kemampatan tanah lembut di Sarawak. Untuk

menyempurnakan kajian ini, lapan sample tanah telah dikumpul dari kawasan-kawasan

yang berlainan, yakni Desa Senadin (Miri), Kampung Punang (Lawas), Lundu

(Kuching), Dan (Mukah), Sungai Miri (Miri) and Upper Lanang (Batang Rajang).

Kajian eksperimen yang berlainan tentang moisture content, Atterberg limit, specific

gravity, grain size analysis, dan consolidation telah dijalankan terhadap smple-smple

tanah itu. Keputusan menunjukkan bahawa pemalar bagi perubahan isipadu, mv untk

semua sample tanah adalah berkadar songsang dengan tekanan. Tetapi, pemalar bagi

consolidation, cv untuk semua tanah yang dikaji tidak mempunyai sebarang trend yang

unik dengan peningkatan tekanan. Tambahan pula, index mampatan, Cc yang dikira

daripada graf e-log P dan dikira dengan menggunakan formula (Cc = 0.009 × (wL-10))

saling dihubungkan dengan nilai index plastik (PI).

iv

Table of Content

CONTENTS Page No.

ACKNOWLEDGEMENTS i

ABSTRACT ii

ABSTRAK iii

TABLE OF CONTENTS iv

LIST OF TABLES vii

LIST OF FIGURES viii

LIST OF SYMBOLS ix

CHAPTER 1-INTRODUCTION

1.1 General 1

1.2 Physical Properties and Classification 2

of Soft soil

1.3 Construction on Soft soil 4

1.4 Statement of the Problem 6

1.5 Objectives of the Present Study 7

1.6 Organization of the Project Paper 8

v

CHAPTER 2-LITERATUREVIEW

2.1 General 9

2.2 Physical Properties of Soft Soils 9

2.2.1 Organic content 10

2.2.2 Water content 11

2.2.3 Specific gravity 13

2.3 One-Dimensional Compression 15

2.3.1 Effect of permeability on consolidation 16

2.3.2 Compression - time relation 17

2.3.3 Estimation of final settlement 22

2.4 Critical appraisal 23

CHAPTER 3-MATERIALS, TEST PROGRAMME AND PROCEDURE

3.1 General 25

3.2 Test Materials 25

3.3 Test Programmes 26

3.4 Test Procedure 27

3.4.1 Moisture content 28

.4.2 Liquid limit and plastic limit 28

3.4.3 Specific gravity 29

3.4.4 Grain size analysis 30

3.4.5 Void ratio, e 31

3.4.6 Consolidation test 31

vi

CHAPTER 4-RESULTS AND DISCUSSION

4.1 General 33

4.2 Moisture content 33

4.3 Grain size distribution 34

4.4 Atterberg limit 37

4.5 Specific gravity 37

4.6 Compressibility characteristics 38

4.7 Consolidation settlement 44

CHAPTER 5-CONCLUSION AND RECOMMENDATION

5.1 General 46

5.2 Recommendation 47

REFERENCES 49

APPENDIX

viii

LIST OF FIGURE

Page No.

Fig. 2.1 Correlation of water content with loss-on-ignition 13

Fig. 2.2 Correlation of specific gravity with loss-of-ignition 15

Fig, 2.3 Distortion of settlement curve by resetting of time zero 18

Fig.2.4 Middleton Wisconsin peat; Settlement --Time 20

curves on various scale

Fig. 2.5 Middleton Wisconsin peat, oedometer test #6, 21

isotaches for loading and reloading

Fig. 2.6 Polder Zegveld peat, w/N - log σv’ for 104 d loading 23

Fig. 4.1 Grain size distribution graph for different clay soil 34

samples

Fig. 4.2 Square root of time method 39

Fig.4.3 e-log P graph for Sample-1 39

Fig. 4.4 mv values of various sample with different pressures 42

Fig. 4.5 cv values of various sample with different pressures 42

Fig. 4.6 Relation between compression index and plasticity index 43

ix

LIST OF TABLE

Page No.

Table 3.1 Test programmes 27

Table 4.1 Physical (index) properties of samples 36

Table 4.2 Consistency limits for different soil samples 37

Table 4.3 Specific gravity of different soil samples 38

Table 4.4 mv values (in m2/kN) for different soil samples 41

with various pressure ranges

Table 4.5 cv values for different soil samples with various 41

pressure ranges

Table 4.6 Cc values for different soil samples 43

Table 4.7 Settlement estimation by using Cc of sample 44

with 1m depth

Table 4.8 Settlement estimation by using mv of sample 45

with 1m depth

1

CHAPTER 1

INTRODUCTION

1.1 General

Normally clay, peat and organic soils considered as soft soil. They show a

wide range in the degree of compressibility. In Sarawak, the peat and soft soil

creates an acute problem for any type of construction (building and road). The

formation of peat soil is a relatively short biochemical process carried on under

the influence of aerobic micro-organisms. Peat materials can be characterized for

geotechnical engineering purposes in various ways depending on the purpose for

which they are being described. The most relevant physical characteristics are

water content, bulk density, organic content, and exchangeable cation; whereas

engineering properties include compressibility, swelling and shrinkage, shear

strength (stability) and permeability.

2

Soft soil (e.g., clay, peat and organic soils) is generally a topic of interest

by the engineering community. Geotechnical engineering challenges especially

associated with embankment and road construction over soft soil (e.g., clay, peat

and organic soils) include potential instability and excessive long-term settlement.

Although construction over such soils is generally avoided, the declining

availability of sites with more favourable foundation soils has necessitated the

development of area underlain by peaty or organic deposits. (O' Loughlin and

Lehane, 2002). However, with the recent advances in the use of soil

reinforcement, construction has primarily become a problem of controlling

settlement (Edil and Den Haan, 1994).

The resurging interest in soft soil as foundation materials have been

underlain by the continual research and study on both the physical and

engineering properties of such soils and the correlation among these properties.

The origin and formation of soil clay minerals, namely micas,

vermiculites, smectites, chlorites and interlayered minerals, interstratified

minerals and kaolin minerals, are broadly reviewed in the context of research over

the past half century. It is concluded that these early overviews may still be

regarded as being generally valid, although it may be that too much emphasis has

been placed upon transformation mechanisms and not enough upon neoformation

processes. (Wilson M.J., 1999)

3

1.2 Physical Properties and Classification of Soft soil

Soft soil, mainly peat, is encountered in tropical and low-lying areas where

water table is near or above ground surface. They are present mostly in surface

soils but in some cases as deep deposits. Soil organic matter originates from plant

or animal remains and is often observed in various stages of decomposition with

an end product known as humas. There are certain terms used in characterising

physical characteristics of peat. Generally, the physical properties of organic soils

are of particular relevance to densification purposes. Organic soil materials consist

of four components', mineral material, organic material, water and air. The

characterization of the physical properties of organic materials is made difficult by

the changes in the proportions of the four components.

Traditionally the study of physical properties was more the domain of soil

mechanics and soil engineering than of soil chemistry. The former express the

characteristics of materials on a volume basis, whereas chemists commonly use

weight ratios. There is a tendency at present to use volume ratios, because it is

more practical to work with. Because of the strong interdependence of the various

physical properties, it is difficult to discuss each individual characteristic

independently. It is thus necessary to make frequent cross-reference. The

important geotechnical terms are water content, fibre content, degree of

humification and ash content, organic content etc.

4

Organic soils, which according to definition contain a varying proportion

of organic matter, include peat (remains of dead vegetation in various stages of

decomposition), gyttja (plant and animal remains deposited in lakes) as well as

organic silts and organic clays. The types of soil differ greatly from each other

with respect to engineering properties.

Classification of peat is a controversial issue with numerous approaches

available for varying purposes. Peat is a naturally occurring highly organic

substance derived primarily from fossilized plant materials. Peat is distinguished

from organic soils by its high organic content (>75%), lower decomposition or

humification, and fibre content. It also refers to a distinct mode of behaviour

different than traditional soil mechanics in certain aspects. A possible approach is

being considered by the American Society for Testing and Materials (ASTM) for

classifying peat soil.

If a soil has less than 5% of organic content, its behaviour is hardly

affected by the organic content, and as such it is termed as inorganic soil. The

organic content of 6 to 20% has effects on the properties of whole soil mass but

still its behaviour is very much like that of inorganic soil. Usually this type of soil

is termed as either organic silt or organic clay. When the organic content of a soil

is in between 21 to 74% percent, the organic matters govern the properties.

Traditional soil mechanics may not be applicable to these types of soils. They are

generally silty or clayey organic soils. Most importantly, if the organic content of

5

a soil is more than 75%, it is considered as peat. Peat soil displays behaviour

distinct from traditional soil mechanics especially at low stresses. (Edil, 1994).

According to Tan the proposed site at Klang, Selangor, Peninsula

Malaysia (Fig. 1.1) is located at the contact boundary of Quarternary Alluvium

and Kenny Hill Formation as shown in Fig. 1.1. The alluvial deposits are

overlying the Kenny Hill Formation of weathered metasedimentary rock type. The

alluvial deposits generally consist of very soft to firm silty Clay up to a depth of

25m to 30m with presence of intermediate sandy layers. Beneath the silty Clay

stratum generally consists of silty Sand. Residual soils (Grade VI) and completely

weathered materials (Grade V) derived from the weathering of Quartzite were

only encountered at about 40m deep. The presence of quartzite rock-type was

further confirmed from the observation of rock outcrop located about 2km from

the site. The behaviour of soft alluvial soils is influenced by the source of the

parent material, depositional processes, erosion, redeposition, consolidation and

fluctuations in groundwater levels. Alluvial soils in Klang area usually show

pronounced stratification and sometimes organic matter, seashell and decayed

wood are present in this deposits.

6

Fig. 1.1 : Location of the Site.

Fig.1.2 : Geological Map of the Site.

The compressibility and permeability relationships of very soft clay is

determined by a finite strain consolidation test with a constant surcharge which

uses Gamma-rays and pore pressure transducers to measure density and pore

pressure profiles, respectively, at various times of the test without hindering the

consolidation process. The constant surcharge applied accentuates the changes

in density and pore pressure profiles enabling them to be measured reliably.

7

These profiles are then used to determine the compressibility and permeability

of the soft clay. A test is carried out to extract these properties, which are used

in a finite strain consolidation theory to predict the settlement, void ratio, and

pore-pressure distributions of other tests done under different initial and

boundary conditions. The predictions are found to agree well with the

experimental data, thus suggesting that the properties determined are accurate

(Tan, 1988).

1.3 Construction on Soft soil

Peat soils have certain characteristics that set them apart from most

mineral soils and require special considerations for construction over them. These

characteristics include: high natural moisture content (up to 1500%), high

compressibility, low strength in natural conditions (typically Cu = 5 to 20 kPa),

high initial permeability, high degree of spatial variability and potential for further

decomposition. Edil (1994) reports a variety of construction methods that have

been developed and used to allow construction of structures and embankments

over soft soil (e.g., clay, peat and organic soils). These methods include;

avoidance, excavation- displacement/replacement, stage construction and

preloading, thermal pre-compression, deep in-situ mixing, stone columns, piles

and so on.

8

Sarawak has the largest peat area in Malaysia with 16500 m2 that makes

up 13% of the state, of which 90% is more than 1 m in depth, Singh (1997).

Geographically, these peats are found in the administrative divisions of Kuching,

Kota Samarahan, Sri Aman, Sibu, Sarikei, Bintulu, Miri and Limbang on their

coastal side.

Ling (1997) conducted a research on stress-void ratio relationship of peat

soil and concluded that the conventional formula cannot be applied for

computation of fill ground in peat area. He proposed a new formula; however, he

was not optimistic of using the formula for calculating settlement without having

rigorous further study. Yogorajah and Ganeshan (1997) worked on application of

ground improvement techniques in soft soil deposits. Of the available methods

they highlighted the common methods of vertical drains with surcharge and the

soil reinforcement by traditional method of locally available material bamboo and

geotextile. They claimed that the traditional method appeared to be economical.

Mc Manus et al. (1997) reported their experience with the peat soil of Sarawak

and their recommendations were similar to that of Yogorajah and Ganeshan

(1997), especially with the peat deposit within a depth range of 3 m to 10 m.

According to Ling (1997), the construction of the Sungai Sarawak Barrage

involves major geotechnical works in soft clay. These include deep excavation

with well pumping for ground water control, pile installation, embankment

preloading and rockfill construction of causeways.

9

1.4 Statement of the Problem

The construction on and with soft soil has never been apprehended as

simple job owing to non-availability of established analytical methods and

construction techniques for a specific site. Several methods of soil improvements

are available (Yogorajah and Ganeshan, 1997). Though a significant volume of

research work has been done on the various aspects of peat soil, yet it appears that

the estimation of settlement still needs further study. Understandably, its use in

practice is so important. The most severe problem associated with peat soil is that

the sample decomposes with time and the properties are getting changed. Thus in

the present study was aimed at investigating the feasibility of using simple tests

like determination of water content, Atterbergs limit and compressibility

characteristics (i.e., co-efficient of volume change, compression index, co-

efficient of consolidation etc.) of various soil samples collected from different

location in Sarawak and to correlate these properties to estimate the settlement in

a simple manner.

There are always two main problems in soft clay, namely stability and

settlement. However, many practising engineers always forget about the

importance of settlement problem. Therefore, more effort should be emphasized

in the process of interpretating soil parameters for settlement analysis (Tan).

10

Soil samples from several selected locations (i.e., Desa Senadin,

Kampung Punang, Lundu, Mukah, Sungai Miri and Upper Lanang) have been

collected and tested for water content-, grain size distribution, specific gravity,

Atterbergs limit indices and consolidation properties. Laboratory tests are to be

done and the data be analyzed to find correlations among the properties

mentioned. The findings may be used in any fill projects by performing simple

tests, avoiding complicated and expensive ones, like water content and plasticity

index to estimate the settlement of a fill.

1.5 Objectives of the Present Study

The present study is aimed at investigating some physical and engineering

properties of soil samples collected from various locations in Sarawak. The main

objectives of the present study are as follows:

(i) To review the available related literature in order to have an

in depth view of the subject.

(ii) To investigate the correlation between water (moisture)

content and the compressibility characteristics mainly

compression index (Cc) of soft soil.

(iii) To investigate the correlation between Atterbergs limits and

the compressibility characteristics of soft soil.

11

1.6 Organization of the Project

This outcome of this investigation is presented in a volume of five

chapters. First chapter is essentially an introduction to the topic and the intended

work. The second chapter includes the review of related literatures. Chapter three

covers test programme, procedure and testing materials. Chapter four comprises

of the experimental results and discussion. To summaries the work, chapter five

presents the conclusion of the study and suggests the recommendations for future

research.

9

CHAPTER 2

LITERATURE REVIEW

2.1 General

The present study aims at finding out a relationship between moisture content

and compressibility characteristics of soft soil (e.g., clay, peat and organic soils). In

this chapter the available literature on inter-relation between composition and

compressibility of mainly peat, organic soil and clay soil have been presented.

2.2 Physical Properties of Soft Soils

The concepts of behavior of inorganic clays have often been applied to peat

and organic soils, with varying degrees of success. It is possible to apply traditional

soil mechanics theory to these soils with special attention and consideration by

10

limitations of methods of characterization owing to anomalies in behavior of peat and

organic soils (den Haan, 1997). The main physical properties of peat and organic soils

are being water content, loss on ignition, organic content and specific gravity. The

engineering properties and thus the foundation behavior are greatly influenced by

these properties.

2.2.1 Organic content

Extensive research has been carried out on the determination of the organic

content of peat. However consensus has not been reached, neither the methods used

nor details of any method. Sometimes, various methods are recommended for

different purposes such as calorific potential or identification of clays etc.

(Andrejko et al., 1983).

Numbers of wet ashing techniques involving chemical analysis are

available for the determination of organic content, but such methods are

generally successful in soils with relatively small amounts of organic matter

(Hobbs, 1986). A more common and effective method is to burn a small soil

specimen in a furnace after drying at 105°C for 24 hours. The difference between

masses before and after burning gives the ash content or loss-on-ignition (N).

The organic content can then be determined by the following expression: