Geological Society of Malaysia Annual Geological Conference 2000

September 8-9 2000, Pulau Pinang, Malaysia

The Characteristics and Engineering Properties of Soft Soil at

Cyberjaya
RoHAYU CHE 0MAR 1 & RAsHID JAAFAR2

1 lnstitut Alam Sekitar Dan Pembangunan (LESTARI), UKM

2 Soil Centralab Sdn. Bhd.

Abstract
This paper provides information on the distribution and characteristics of peat and organic soil which is distributed
around the Multimedia Super Corridor area. Peat and organic soils are the ultimate soft soils in engineering terms. The
behavior of peat and organic soils is usually determined using the concepts and methods developed for inorganic soil.
However, important anomalies exist, and these are given emphasis in the present overview of the mechanical behavior
of these soils. Peat and organic soils are difficult to sample and test using normal soil techniques, and in fact there is
not even an adequate engineering system in place for classifying these soils. The characteristics and engineering
properties of these soils are presented with respect to its earthwork and geotechnical performance. A preliminary
classification system of these soils are also proposed.

Cirian dan Sifat Kejuruteraan Tanah Lembut di Cyberjaya

Abstrak
Kertas ini membincangkan taburan dan kriteria bagi gambut dan tanah berorganik yang meliputi sekitar kawasan
Koridor Raya Multimedia. Tanah ini diklasiflkasikan kepada tanah asas mengikut istilah kejuruteraan. Sifat tanah
gambut dan organik ini dikenalpasti menerusi konsep dan kaedah penilaian bagi tanah tak berorganik. Walau bagaimanapun
ianya dapat dibezakan dari segi sifat mekanikal berdasarkan anomali yang wujud. Sehingga sekarang masih belum
terdapat sebarang sistem pengelasan bagi tanah ini dan ianya sukar untuk disampel dan diuji mengikut kaedah biasa.
Kriteria dan sifat kejuruteraan tanah gambut dikawasan ini diberikan berdasarkan keupayaan geoteknik dan kerjatanah.
Satu sistem pengkelasan bagi tanah ini juga diperkenalkan.

INTRODUCTION SITE GEOLOGY

As development proceeds at a rapid pace throughout The data in this paper is obtained from pre-construction
the region, projects are increasingly being located on poor and construction soil investigations conducted during the
ground. Malaysia has considerable tracts of low lying land, Cyberjaya Development project. The geology and soil
which comprise strata that impose difficult design and distribution of the study area is shown in Figure 1.
construction conditions, due to the presence of soft clay or
peat soils. Peat and Soft Soil
Slope and embankment failures on poor ground The low-lying swampy areas are extensively covered
during construction has become a problem, and with the with peat of an average thickness of 2.0 m, although
accelerated rate of development, this problem will thickness of up to 10.0 m has been recorded. The peat can
certainly worsen unless proper planning and management normally be differentiated as dark brown spongy amorphous
of the site is adopted at an early stage of any proposed peat and spongy fibrous peat. The peat is also associated
construction. In order to facilitate proper planning, a with decayed wood and root. It is formed under both
study was initiated to investigate possible engineering topogeneous and ombrogenous conditions.
and geological factors that have contributed to earthwork Immediately below the peat is a layer of very soft to
problems. The study was focused on the Cyberjaya soft compressible clay, which has generally been described
Development project. as marine clay. This soft clays is light grey in color and is
To improve understanding of the problems that are very soft to very stiff silty clay to sandy silty clay. The soft
likely to be encountered, the characteristics and engineering soil deposits are categorised as the Pengkalan Member of
properties of the soft soil in this area was determined. The the Bernas Formation (Bosch, 1988). The total depth of
distribution of this soil in the study area was also peat and very soft clay over much of the area is less than
investigated. In this paper, emphasis will be made on 5.0 m to 7.0 m (Figure 2). Depths of up to 15.0 m to 25.0
addressing the selection of parameters for the design of m have, however, been identified along the line of the
slopes or deep excavation. perimeter road and in the park area (Plate 1).
314 R OHAYU CHE 0 MAR & R AS HID J AAFAR

I
,.! ...}
/
'. .

J4ead:
Korm:y l:lill Formation
c:::J (Schilt. pbylilo, quaaitc and •W..)
Shallow d<:plb of
~ Sot\ DlJitnlilll {2.-3ru)

!x•,wil Aboul 6m Sot\ material Qn""""""Y

•.. t..--~-- Tot>l of IOm 110ft mot.o.! Oopooit
CJ (Pt111t+ SoR Soil)
]
l-2mpea<
EJ 6-1 Om mino llliling(Loooo Sand)
2-3mSoftJillllorial

Figure I: Map show ing the geology and soil distribution in the stu dy area.

Geological Society of Ma laysia Annual Geological Confe rence 2000

 THE CHARACTERISTIC AND ENGINEERING PROPERTIES OF SOFT SOIL 315

--------- ------- ---------- ------ ------ ------------------------

---------
1~ ~---------- PEAT with
PEAT with decomposed wood
decomposed wood PEAT with
1.5 o aod rootlet 1.5 I decomposed wood 1.5 3
aodrootlet
(amorphous peat)
3.0 I 3.0 2 3.0 2

soft medium stiff

4.5 I silty clay (traced of . ~ ,; ..._ soft silty CLAY S I soft silty CLAY
4. with dec:ayed wood
olpllic matter) _, _.. ,... -..., with dec:ayed wood
.... _, ' .....
-----6.0:5------------- _.. 'n
6.u- 6
'-
.......... 6.0 2
.....
..........
7.5 4 7.5 9 -......_-... 7.5 I
.................... ._,

9.0 6 silty clay with trace of organic matter 9.0 12

-------
9.0 4 -----
firm silty CLAY

10.5 8 10.5 14 10.5 9

firm silty CLAY
with saud
12.0 9 12.0 12 12.0 13

13.5 9 13.5 10 13.5 12

15.0 ~5.0 15.0 11 15.0 IS

Figure 2: Soft soil profile.

The deposition of soft soil in the site are in single Ground Water
layers of 2.0 m to 25.0 min thickness.
In the plains and valleys, the groundwater level is
Residual Soil, Colluvium and Bedrock generally near to the ground surface, at depths of at between
0.1 m and 0.5 m. The level is slightly lower at the upper
The high ground in the study area rises between 30 m
end of some valleys but even then it is not more than I m
to 150m. This high ground is mainly covered by residual
in depth.
soils, derived from the weathering of foliated
metasedimentary rock, which occur as a series of parallel
hills aligned in a south-easterly to north westerly direction
SOFT SOIL DESCRIPTION, TEST
with a dip of between 65° and 95°. The metasedimentary METHOD AND CLASSIFICATION
rocks are inferred to be of the Kenny Hill Formation
comprising essentially sandstone, shale, phyllite and Description
quartzite (Plate 2). The denudation of residual soils has led Soft clay is defined as soils with large fractions of fine
to the formation of the present valley systems. This contact particles such as silty and clayey soils, which have high
zone between the soft sediments and the residual soils is moisture content, peat foundations and loose sand deposits,
quite complex and an overlying deposit of colluvium located near or under the water table (Kamon and Bergado,
generally masks its location. 1991).
The colluvium is generally encountered as soft to stiff Any discussion on construction involving peats or soft
silty clay overlying medium dense to dense very clayey soils requires a definition of the terms used to describe
gravel or sand. The residual soil is typically firm to stiff, these materials. Depending on the geographic origin and
becoming very stiff and hard sand silty clay with increasing training of the engineer or geoscientist involved, a "peat/
depth. Residual soil eventually grades into moderately to soft soil" may be defined as soil with an organic content
completely weathered rock, a hard dense clayey sand or greater than anywhere from 20% to 70% of the total weight.
sandy silt but generally only at depths greater than 20 m. At worst "peat/soft soil" may be used interchangeably with

September 8-9 2000, Pulau Pinang, Malaysia

316 ROHAYU CHE 0MAR & RASHID JAAFAR

the hand. The color and form of fluid that is extrude

between the fingers is observed together with the
pressed residue remaining in the hand after squeezing .
The degree of humification on a 10-point scale, Hl t
H10 , is obtained by comparing the observations t
those described in Table 1.
Atterberg Limits: The fibres in peat make determination
of the Atterberg limits difficult , and results depend
strongly on the methods used to prepare the samples.

USCS Classification
This classification is used by most engineers. It is
outlined in Tables 2 and 3. The definition of having greater
Plate I: Peat at the proposed Cyberjaya Park, Cybetjaya Flagship
than 75 % organic content, is most commonly used by
Zone. engineers in North America, ASTM D4427, Classification
of Peat Samples by Laboratory Testing, is described as
follows:
(a) Slightly Organic Silts or Clays will most probably
appear as inorganic fine grained soils, probably black
or dark brown in colour, have an organic odor and
possibly some visible organic remains. Their plasticity
limits should be evaluated as for other fine grained
inorganic soils. These soil would then be classified as
silts or clays of low, medium or high plasticity , for
example ML, CH. It is suggested that a small "o" be
appended to indicate that they are slighty organic
differentiate them from purely inorganic soils, MLo
and CHo.
(b) Peat on the other hand may well appear to be completely
organic, contain recognizable plant remains, have a
Plate 2: View of the Kenny Hill Formation at the Cyberjaya Park. low density and also black or dark brown. Following
a Von Post test it could be categorised as listed in
the term "organic soil" to describe any soil that appears to Tables 3 and 4.
have some organic content. In the Unified Soil Classification Thus, for example, a peat could be described as a
System (USCS) peats are described as soils consisting Fibrous Peat and given a symbol, Ptf.
"predominantly" of plant remains, often with a distinctive (c) Organic Soils is more difficult to sub-divide lying , as
smell. Organic clay, silt or sand contains "substantial it does, between the other two categories. There is
amounts" of vegetable matter. insufficient infmmation at present to determine whether
this group can be meaningfully sub categorised.
Test Method Currently, for these materials, an attempt should be
The following parameters were determined to made to provide both the Atterberg Limits and the
characterize the soft soil: Degree of Humification to allow establishment of a
Water content : The water content is measured using database from which future analyses can be made . In
procedures specified in ASTM D2974 orBS 1377. fact, it may be that neither of these tests work for the
Organic Content : As a percentage of dry weight. The Organic Soil category. The degree of humification is
organic content is measured in the laboratory using a only meaningful for soils that are predominantly
Loss on Ignition Test, ASTM D2974 orBS 1377 Part organic. The presence of inorganic material tends to
3(4), or a Chemical Oxidation Test, BS 1377 Part 3(3). confuse the interpretation of the degree of humification.
• Degree ofHurnification (Decomposition) of the organic Similarly the Atterberg limits are only truly meaningful
material. The degree of humification represents the for soil that are primarily inorganic and the presence
degree to which the organic remains have decayed. of organic material may well interfere with those tests.
The range lies between fresh plant remains and a
completely decayed visibly amorphous material with VARIATION OF SOFT SOIL PROPERTIES
no recognizable plant structure. Where a soft so il/peat
lies within this spectrum radically affects its engineering The so il data in this paper is from pre-construction and
behaviour. In the field it may be assessed by the Von construction soil investigations conducted for the Cyberjaya
Post Squeeze Test. A sample of the peat is squeezed in Development project. Unlike other construction materials ,
Geological Society of Malaysia Annual Geological Conference 2000
 THE CHARACTERISTIC AND ENGINEERING PROPERTIES OF SOFT SOIL 317

Table I: Von Post degree of humification.

Degree of
Description
Humitication
Completely undecomposed peat which releases almost clear water. Plant remains easily identifiable. No amorphous
HI
material present.
Almost completely undecomposed peat, which releases clear or yellowish water. Plant remains still easily between
H2 the fingers. Plant remains still easily identifiable. No amorphous material present.
Very slightly decomposed peat which releases muddy brown water, but for which no peat passes between the fingers.
H3
Plant remains still identifiable and no amorphous material present
Slightly decomposed peat, which releases very muddy dark water. No peat is passed between the fingers but the
H4
plant remain are slightly pasty and have lost some of identifiable features.
Moderately decomposed peat which releases very "muddy" water with also a very small amount of amorphous
H5 granular peat escaping between the fingers. The structure of plant remains is quite indistinct, although it is still
possible certain features. The residue is strongly pasty.
Moderately strongly decomposed peat with a very indistinct plan structure. When squeezed, about one-third of the
H6 peat escapes between the finger. The residue is strongly pasty but shows the plant structure more distinctly than
before squeezing.
Strongly decomposed peat. Contains a Jot of amorphous material with very faintly recognizable plant structure.
H7 When squeezed, about one-half of the peat escapes between the fingers. The water, if any is released, is very dark
and almost pasty.
Very strongly decomposed peat with a large quantity of amorphous material and very dry indistinct plant structure.
When squeezed, about two-third of the peat escapes between the fingers. A small quantity of pasty water may be
H8
released. The plant material remaining in the hand consists of residual such as roots and fibers that resist
decomposition.
Practically fully decomposed peat in which there is hardly any recognizable plant structure. When squeezed, almost
H9
all of the peat escapes between the fingers as a fairly uniform paste.
Completely decomposed peat with no discernible plant structure. When squeezed, all the wet peat escapes between
HIO
the fingers.

Table 2: Organic content of soil. 2% and 25%. On the other hand, the clay content increases
with depth to a depth of 16m from 25 % and 75%.
Organic
Basic Soil Type Descriptor The variations of the Atterberg limit increases with
Content(%)
depth (Figure 6). The typical range of plastic limit (PL) is
Clay or Silt or Sand Slightly Organic 3-20 between 10% and 80% while for the liquid limit (LL) it is
Organic Soil Organic Soil 20-75 between 10% and 90%. The plastic index (PI) is from 3%
Peat Peat and 50%. The liquid limit increases with depths, reflecting
>75
the decrease in sand content with depth.
Figures 7 shows the variation between the following
soft soil is non-homogeneous and its properties are highly compressibility parameters: compression index (Cc), the
variable and complex. recompression index (Cr), and the coefficient of
The distribution of the soft soil ranges from fibrous to consolidation (Cv) against depth. Generally, the
amorphous and consists of peat, clay and silt (Table 5 and compressibility parameters increase with depth. This
Figure 3). Some engineering properties of the soft soil increase is consistent with the effect of the increase in
identified from boreholes is shown in Table 6. The natural moisture content with depth and the decrease in the sand
water contents are greater than liquid limits at most depths. content with depth.
The natural moisture content of the Cyberjaya soft soil is The variation of recompression ratio (Cr) with depth
extremely variable and range between 10% to 700%. Figure indicates that there are no obvious trends between the
4 shows the trend decreasing with depth. The high water recompression ratio (Cr) and depth. Consequently, the
content is due to the nature of soft soil characteristics and variability in this measure is more a function of the soil test
its location below the water table. than soil properties.
Wet seiving was used to obtain the grading curves The preconsolidation pressure (Pc) is important in
shown in Figure 5. Grain size distribution range from sand determining the settlement of soft soil under external loading.
to clay size. The profiles show decreasing clay content and Figure 8 shows the trend between preconsolidation pressure
increasing silt content with depth, i.e. upper parts of (Pc) and depth. The trend shows a general increase in Pc
distribution profile have higher clay content than lower with increasing depth. Ho and Dobie (1990) describe how
part. The clay content generally decreases with depth, from uniform incremental loading can be used to determine Pc

September 8-9 2000, Pulau Pinang, Malaysia

 Table 3: Qualifying terms and symbols for peats and organic soil.
Von Post Degree of
Organic Components Qualifying Terms Symbol
Humification
Peat Pt
Hl-H3 Fibric or Fibrous (over 66% fibre) F
H4-H6 Hemic or Moderately Decomposed (33-66%) H
H7- HlO Sapric or Amorphous (less than 33%) A
Organic Soil 0

Table 4: Malaysian Soil Classification Systems for engineering purposes and their field identification for organic soils and peat (after JKR and Jarrett, 1995)

Sub-group laboratory identification

:IJ
Sub 0
Soil Group Field Identification
Description
Group
Symbol
Group
WL
(%)
Degree of
Humification
Sub Group Name ~
c
Symbol (')
J:
Slightly Slightly Mo Mo Slightly Organic SILT (Co) Usually very dark to black m
0
Organic Organic and contain a small amount
Soils SILT of organic. Often has ~
S20
Fo Clo < 35 Slightly Organic CLAY of low plasticity distinctive small
Cio 35-50 Slightly Organic CLAY of intermediate plasticity ~
J:
Organiic Slightly Co Cho 50-70 Slightly Organic CLAY of high plasticity a
Content Organic Cvo 70-90 Slightly Organic CLAY of very high plasticity c...
3%-20% CLAY Ceo >90 Slightly Organic CLAY of extremely high plasticity ~
:IJ
Organic Subdivision of Organic Soils is difficult, as neither
Soil the plasticity tests not the humification tests are
Organic reliable for them. Such a "best attemp"is the
ORGANIC
Soil Organic 0 probable outcome of subdivision leading to
SOIL
Content description such as "Fibrous ORGANIC SOIL"or
20%-75% Amorphous ORGANIC SOIL of Intermediate
Plasticity
Peats Dark brown to black in
colour. Has low density so
Organic Ptf Hl-H3 Fabric or Fibrous Peat seems light. Contains of mass
Content PEAT Pt Pth H4-H6 Hemic or Moderately Decomposed Peat is organic so if fibrous the
more than Ptn H7- HIO Sapric or Amorphous Peat mass will be recognizable
75% plant. More likely to smell
strongly if humified
 THE CHARACTERISTIC AND ENGINEERING PROPERTIES OF SOFT SOIL 319

Table 5: Profile of typical soft soil in Cyberjaya.

Basic Soil Von Post Qualifying

Depth (m) Description Descriptor Symbols
Type Classification Terms
Dark brown very soft CLAY with organic
1.00- 1.80 Peat Peat HI- H3 Fibrous Pt
material with some of decayed wood and roots

3.50- 3.95 Dark grey soft sandy silty CLAY Organic Soil - H3 Fibrous f

Light greyish brown with slightly of greenish Slightly Moderately

4.50-4.95 Clay H3- H4 H
grey soft silty CLAY with traces of sand Organic Decomposed
Pale yellow to brownish light grey clayey Slightly Moderately
5.00-5.80 Silt H5 H
SILT with traces of sand Organic Decomposed
Light grey with slightly of greenish grey silty Slightly Moderately
6.00- 6.80 Clay H5- H6 H
CLAY with traces of SAND Organic Decomposed
Pale yellow to light brown slightly sandy Slightly
7.00- 7.80 Silt H7 Amorphous a
clayey SILT Organic
Yellowish brown with traces of purple stiff Slightly
8.00-8.45 Silt H7 Amorphous a
clayey SILT with traces of sand Organic
Yellowish brown medium stiff sandy silty Slightly
9.50- 10.30 Clay H7 Amorphous a
CLAY Organic

Table 6: Some engineering properties of typical borehole samples of soft soil.

Depth Bulk Moisture Plastic Liquid Plastic Organic

(m) Density Content Limit Limit Index
Clay Silt Sand Gravel LOI 0"3 0"3-<JI c u
Pc e Cc Cr Cv
Content
"
I * 610 NP * 48.1 * *
2 425 32 74 42 39 26 35 0
3 205 33 67 34 50 36 14 0
4 1.77 143 31 63 32 48 42 10 0 100 114 55 450 0.90 0.35 0.18 27.31
5 1.82 96 31 54 23 59 40 1 0 120 63 44 450 0.90 0.26 0.14 26.87
6 1.81 45 37 99 62 74 20 6 0 65 124 66
7 1.92 35 30 77 43 57 29 14 0 75 105 98
8 2.02 21 17 28 21 27 14 59 0 230 0.60 0.20 0.13 23.90 0.51
9 2.02 18 18 41 23 25 11 64 0 200 324 141

1\ibisture Content Bulk Density

0 200 400 600 800 0.00 0.50 1.00 1.50 2.00 2.50 3.00
0.00 --~-~--~---~ 0.00 -~-~~-~~--;

• • ~...

-·'
2.00 2.00
~-~
4.00 4.00 .s.
6.00
i~ 6.00
~
7.
~

g 8.00
'8. 10.00 '
)
g
£
8.00

10.00
.....
CD
0 12.00
•• c..
CD •·--•
0 12.00

14.00 • 14.00
••
16.00
• 16.00
•
18.00
• 18.00
•
20.00 20.00

Figure 3: Plots of moisture content and bulk density with depth (m).

September 8-9 2000, Pulau Pinang, Malaysia

320 ROHAYU CHE 0MAR & RASHID JAAFAR

Clay(%) Silt(%) Sand(%)

0 25 50 75 100 0 25 50 75 100 0 25 50 75 100
0.00 0.00 0.00

2.00 2.00 2.00

4.00 4.00 4.00

6.00 6.00 6.00

~ 8.00 ~ 8.00 8.00

~
£10.00 £10.00 £ 10.00
D.. D..
Q) D..
Q) Q)
012.00 012.00 0 12.00

14.00 14.00 14.00

16.00 16.00 16.00

18.00 18.00 18.00

20.00 20.00 20.00

Figure 4: Plots of clay, silt and sand contents with depth.

Aastic Limit (%) Liquid Limit (%) Aastic Index (%)

0 25 50 75 100 0 25 50 75 100 0 25 50 75 100

0.00 0.00

........
0.00

2.00

4.00
••••
1..
t.•:.
2.00 ...•_. .. •••• ..••• • 2.00

4.00
. .:-
• •
• ••••
4.00
••• •
6.00
.,
•••"#• •
~··
~
6.00
• • I .....
I • ......
6.00
.· .......
'f' ••

~
8.00
•• • ~
8.00
•• • • ~
8.00 rl'l' •
£ 10.00 • \ t 10.00 • • • £ 10.00 • • •
• • • •
..
D.. D..

0
Q)
12.00
Q)
0 12.00
• Q)
0 12.00
•
14.00 14.00
•• 14.00
••
16.00
• 16.00
• 16.00
•
18.00
• 18.00
• 18.00
•
20.00 20.00 20.00

Figure 5: Variation ofthe Atterberg limits with depth.

more accurately than recognized international standards. In high illite. Figure 10 shows the relationship between the
this trend, Pc for soft soil deposits may be determined together plasticity index, percentage of clay fraction and the activity
with the extent to which it will consolidate. This is extremely of the clay. The figure indicates that the clay samples from
useful when any ground treatment is to be undertaken. this soft soil have activities ranging from 0.2 to more than
The plasticity chart plot (Figure 9) shows that the soft 2.0. The liquidity index falls in the low expansion to medium
soil material are variable. Generally, the soft soil material expansion categories.
can be classified as very low plastic to highly plastic. The Figure 11 shows that soft soils have range from inorganic
influence of increasing clay content on the plasticity index clays of high plasticity limits into inorganic silts of high
is also depicted in Figure 9. In accordance with Skempton compressibility and organic clays. The Cyberjaya soft soils
(1953), the activity index (AI) is an indicator of clay is similar to the organic silt and clay of Venezuela Clay and
mineralogy. A high activity index (AI > 1.25) usually New London Clay.
denotes montmorillonite, while a low activity index (AI <
0.75) denotes kaolinite. SUMMARY AND CONCLUSION
The results from the study area, shows that the soft soil
have a high activity index (AI> 1.25), even though the clay This paper provides an overview of the distribution
mineralogy of the soft soils comprise mainly kaolinite and and characteristics of soft soil in Cyberjaya, with emphasis

Geological Society of Malaysia Annual Geological Conference 2000

 THE CHARACTERISTIC AND ENGINEERING PROPERTIES OF SOFT SOIL 321

Recompression Index (Cr) Coefficient of Consolidation (Cv)

Compression Index (Cc)
0.00 0.25 0.50 0.75 1.00 1.25 1.50 0~0 0.25 OBO 0.75 1~0 1.25 1BO 0.00 25.00 50.00 75.00 100.00

...- ..
0.00 -~-~-~~-~---1 0.00 -r-~-~-~~~~--; 0.00 -r--~--~-~---~

2.00
•••• • 2.00 2.00
•
4.00
• 4.00 4.00
•
•• •• • • ••••
6.00
'
• ••
• 6.00 ,.•• • 6.00

6.00 6.00
~
6.00
• ~ • ~ •
:5
Q.
10.00 • :5
Q.
10.00 • :5
Q.
10.00 •
Q) Q) Q)

0 12.00 0 12.00 0 12.00

14.00 14.00 14.00

16.00
• 16.00
• 16.00
•
16.00 16.00 16.00

20.00 ,L__ _ _ _ _ _ _ ___,

20.00 20.00

Figure 6: Variation compressibility parameters with depth.

Preconsolidalion Pressure (Pc) LJ.UPPER R.ASfiCITY a-tART

0 200 400 600

0.00

•
- • 50
2.00
•
4.00
.,.I
6.00 • • ••
6.00
~ •
:5
Q.
10.00 •
Q)
0 12.00 10

14.00

16.00
• 10 20 30 40 50 60
Liquid Lirrit (%)
70 80 90 100 110 120

16.00 Figure 8: Modified plasticity chart for use with Unified Soil
Classification system. Soil represented by points within shaded area
20.00 ,L__ _ _ _ _ _ _ _ ___J
are considered borderline and are given dual symbols (after USBR,
1974). Note: L:low; !:intermediate; H:high; V :very high; E:extremely
Figure 7: Plot ofpreconsolidation pressure (Pc) with depth.
high; M:silt; and C:clay.

on its anomalies relative to the behaviour of inorganic • Methods of analysis have been developed that will
clays. Some of the anomalies and outstanding characteristics allow greater confidence in design involving these soft
as well as the research needs are listed below: soils.
• Water content can be used to identify and compare the
• Deposits of peat and organic soils are extremely range of different soft soils by using the Atterberg
variable, large differences occur over centimeters or Limit characteristics.
decimeters. The variability extends throughout all scales • The distribution of Cyberjaya soft soil ranges from
up to the kilometer scale in many cases. fibrous to amorphous and consists of peat, clay and
• Any site investigation involving organic soils must silt.
involve measurement of the organic content of all • Generally, Cyberjaya soft soil material can be classified
forms of organic soil and the degree of humification of as very low plastic to highly plastic.
soft soil. A rational engineering classification system • Cyberjaya soft soils is similar to organic silt and clay
must be adopted for soils with an organic content. of Venezuela Clay and New London Clay.

September 8-9 2000, Pulau Pinang, Malaysia

322 ROHAYU CHE 0MAR & RASHID JAAFAR

••r----n.----,-----r-----r,~--,-----~--~r----,----~
There is a need for detailed mapping of the Cyberjaya
area to determined the extent of the terrain that is covered
50 by peat, as defined from the engineering and geology
perspectives. Isopach contours to delineated the thickness
~·· of the peat should also be established. In addition, other
I
~30
varieties of soft soils should be delineated.

~
~ 20 ACKNOWLEDGEMENTS
.:.--.:::-1··~
-;-r=~..-;:::::-.~---r -.-..-·~"!>~
0 •• • ..

I i The authors are grateful to Cyberview Berhad,

10

I .. i.. i --i--1- Cyberjaya Development, and Pengurusan Lebuhraya Berhad

for permission to publish this paper.
10 20 30 40
Oay Fraction(%)
50 60 70
•• 90

Figure 9: Chart indicating activity of clay. REFERENCES

Amaryan, L.S., 1993. Soft soils properties and testing methods.
60 Rotterdam: A.A. Balkema.
ASTM D 2974.1983. Test for moisture, ash and organic matter of
50
peat materials. America Standards Institution.
Bosch J.H.A. 1988, "The Quarternary Deposits in the Coastal
+:
I Plains ofPeninsular Malaysia", Geological Survey ofMalaysia,
.!:!- 40
--i.- ·: · - r-L, [lp' ,73 (120)] Report No. QG/l.

~.:..t ~ -r- T-- +-- r

.,Iii BS 1377. 1975. Methods of test for soils for civil engineering
.E
~ 30 purposes. British Standards Institution, London.
~
~~- +- +~;;;:+:::~-
~/ , , , ln010anic dots of , Casangrande, A.l932. "Research on the Atterberg limits of soils",
0::20 Dim Terzaghi, K., Peck, R.B.dan Mesri, G. (pnyt) Soil
I I I I I I Mechanics In engineering Practice, him, 24-27. New York:

10
I I I I I I John Wiley & Sonc, Inc.
Ho, H .S ., & Dobie, MJ .D., 1990. Consolidation testing: alternative
- lno~BniClis-of¥eCuU'"jCOmP1ssibH-,~-
an1 Organt Silts 1 1 loading pressure for soft clays in Proceedings. Seminar on
Geotechnical Aspects of the North South Expressway,
10 20 30 40 50 60 70 60 90 100 110 120 November 1990, Kuala Lumpur. (Unpublished),hlm. 135-
Liquid Lirrit, wl
139.
Figure 10: Correlation between the Atterberg limits using the Anderson, J.A.R. 1983. Tropical peat swamp, bog, fen and moor,
plasticity chart (after Casagrande, 1932 in Terzaghi & Peck, 1995). Regional Studies. Amsterdam: Elsevier Scientific Publishing
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Jabatan Kerja Raya Malaysia and Jarret, P.M.l995, Geoguide 6:
60 Site Investigation for Organic Soils and Peats,JKR Document
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50
Kamon, M. And Bergado, D.T. 1991. Ground Improvement
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Mech.Found.Eng'g., Bangkok, Thailand, 2. 526-546.
~40 N.B.Hobbs. 1986. "Mire morphology and the properties and
~c: behaviour of some British and Foreign Peats", Quarternary
~30 Jour of Eng. Geo.l9(4): 7-80.
:g Gltal cia~ (Bosi:;;;J:it, Skempton, A.W., 1953. 'The colloidal Activity of clay'. Proc. 3rd
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U .S.Bureau ofReclamation., 1974. Earth Manual,2"ded. Washington
10
D.C.,8l0

0 7.
10 20 30 40 50 60 70 80 90 100 110 120
Liquid Lirrit(%)

Figure 11: Relationship between Liquid Limit and Plasticity Index

for typical soils (after Casagrande, 1932 in Terzaghi & Peck, 1995).

Geological Society of Malaysia Annual Geological Conference 2000