Soil Investigation at

Mohammed Sultan Road

For M/s Urban Redevelopment Authority

Purchase Order No. URA000EPO06000465 Issue Date : 25-04-2006

Date: 7th July, 2006

Company Registration No: 198403839N

TABLE OF CONTENT Page

1.0 INTRODUCTION 1

2.0 SCOPE OF WORK 2

2.1 Site Condition 2

2.2 Field Investigation 2

2.2.1 Drilling 2

2.2.2 Standard Penetration Test 2

2.2.3 Undisturbed Sampling 3

2.2.4 Disturbed Sampling 4

2.3 Laboratory Tests 4

2.3.1 Moisture Content 4

2.3.2 Bulk and Dry Density Determination Tests 4

2.3.3 Unconsolidated Undrained Triaxial Compression Test 5

3.0 RESULT OF SOIL INVESTIGATION 5

3.1. Subsoil Condition 5

3.2. Laboratory Tests 7

1

1.0 INTRODUCTION

1.1 General

This report presents the soil investigation based on 3 boreholes, conducted at

the project site, (See location map in APPENDIX-B). The main purpose of the soil

investigation is to obtain and understand the geotechnical information on the subsoil

conditions required for the design and construction works.

a) Name of the Project : Project Site at Mohammed Sultan Road

b) Location : Mohammed Sultan Road

c) Client : Urban Redevelopment Authority

d) Period of Work : Field Work

30 June - 04 July, 2006 e) Scope of Work : Field Work

Number of Borehole 3 nos.

Drilling in soil 60.58 m.

Standard Penetration Test (SPT) 20 nos

Undisturbed Sample (UD) 5 nos.

Disturbed Sample (DS) 15 nos.

2

2.0 SCOPE OF WORK

2.1 Site Condition

The project site is located at the corner of Mohammed Sultan Road and

Nanson Road. The ground surface at this site behaves a flat and smooth landscape.

The key plan of the project site, including location of the boreholes, is shown

in APPENDIX-B.

2.2 Field Investigation

The field work involved in the geotechnical investigation was carried out as

recommended in BS 5930: 1981 “Code of Practice for Soil Investigation”. Prior to

commencement of the site investigation, trial pit up to 1.5m in depth was conducted at

each borehole before drilling. Summary on quantity of field works for this project is

listed in APPENDIX–A (Table 1).

2.2.1 Drilling

Drilling was carried out using hydraulic feed rotary boring machine. A metal

crown bit as a cutting tool was attached at the lower end of the drilling rods and

circulated mud water was pumped through hollow rods into the bottom of borehole to

wash out the cuttings to ground surface.

3 nos. of boreholes were performed at 3 points namely, BH-1 to BH-3. All

boreholes were terminated when drilling encountered underlying rock and showed

rebounding effect on the drill stem, or as per instruction from the client representatives.

The diameter of the borehole is 100mm. The boring log data is summarized in

APPENDIX-C. In this project, total drilling depth in soil horizon is 60.58m.

2.2.2. Standard Penetration Test

This test is done in accordance with BS 1377: 1990 Part 9 and covers the

determination of the resistance of the penetration of a split-barrel sampler and

obtaining disturbed samples of the soil for identification purpose.

3

It was performed using a split-barrel sampler connected to the lower end of

boring rods. The sampler was driven into soil by means of a 63.5kg hammer falling

freely through a height of 76cm onto an anvil attached to the top of the rods. A trip-

release mechanism and guiding assembly were used to control the falling hammer and

the driving energy was thus transmitted through the rods to the SPT sampler. The

sampler was driven 45cm into soil with the number of blows required for each 15cm

of penetration recorded. The resistance, N-value, was taken as the number of blows

for the last 30cm of penetration.

When 100 blows were reached before the full penetration of 30cm, no further

blows were applied and the final penetration was recorded. At the end of the test, the

sampler was withdrawn and some extracted soil was placed into a plastic container

and then labeled. These samples were used to describe the type of soil existing in the

boring points.

In this project, total 20 numbers of SPT were taken in order to get the

information and technical data on the strength and type of soil (See Table 1).

2.2.3 Undisturbed Sampling

Undisturbed sampling was carried out by using a thin-wall tube sampler with

outer diameter of 75mm. Prior to sampling; the borehole was flushed with water to

remove the remnants left at the bottom of the borehole. The bottom was measured to

confirm the depth at which the soil sample was taken. The sample tube was lowered

down to the bottom of the hole and jacked into soil. After the sample tube was jacked

to the required depth, the sample tube was taken out to the surface. Wax was then

applied to form a seal on both sides of the UD tube and labelled properly before

transporting to the laboratory for testing.

In this project, total 5 numbers of undisturbed samples were collected by

taking UD samples at the depth of 3.0 & 6.0m from every borehole whenever the

conditions are favourable. (See Table 1).

4

2.2.4 Disturbed Sampling

Disturbed samples were taken from a split tube sampler for identification

purpose, and were stored in sealed plastic containers. In this project, 15 number of

disturbed samples were collected. (See Table.1).

2.3 Laboratory Tests

The following Laboratory tests are carried out on the undisturbed samples

obtained from the boreholes. Summary of test results are listed in APPENDIX-D.

- Moisture Content

- Bulk and Dry Density Determination Tests

- Unconsolidated Undrained Triaxial Compression Test

The purpose of laboratory tests is for the evaluation of shear strength,

compressibility characteristics and classification of soil properties. All tests were

carried out in accordance to BS 1377. Classification of soil types is based on the

Unified Soil Classification System (USCS).

2.3.1. Moisture Content

To determine the moisture content of soils, a soil sample is dried at a

temperature of 105°C to 110°C for about 24 hours. The loss in weight of the soil

sample represents the weight of moisture in the soil. The moisture content of the soil

to the dry weight of soil in percentage is the moisture content of the testing soil. This

test if performed in accordance with BS 1377 : Part 2 : 1990 #3.

2.3.2. Bulk and Dry Density Determination Test

The bulk density of a soil is the mass per unit volume of the soil deposit

including any water it contains. The dry density is the mass of dry soil contained in a

unit volume. Both are expressed in Mg/m 3, which is numerically the same as g/cm3. It

was determined at the laboratory by using the linear measurement method approached

by B.S. 1377 : 1990 Part 2 : Test 7:2

5

2.3.3. Unconsolidated Undrained Triaxial Compression Test (UU)

Unconsolidated undrained triaxial compression tests were conducted to

determine the undrained shear strength of the soil. This test is performed with the

drain valve closed for all phases of the test and before the sample has a chance to

consolidate. That is, the undisturbed samples (on 38mm diameter x 76mm length)

are sheared under undrained condition. It is based on the test method approached by

B.S 1377 : 1990 Part 7 : Test 9.

3.0 RESULTS OF SOIL INVESTIGATION

3.1 Subsoil Condition

This section briefly describes the soil conditions encountered at site. Detailed

soil conditions are presented in each log of boring in the Appendices of Borehole Logs.

The summary of borehole data is given in the form of a Generalised Sub-Soil

Profiles (see Cross-Sections) which interpolate conditions between boreholes but the

results are not necessarily accurate representations of true conditions on site.

Based on the data collected from 3 number of boreholes, it can be classified

that there are 1 layer of back fill soil and 4 types of soil strata, represent by Sandy

Clay [Alluvial Member] and Marine Clay [Marine Member] from Kallang Formation,

followed by Silty Clay and Silty Sand of Old Alluvium, predominantly distributed the

project area. The bore log data and their generalized subsoil profiles are shown in

APPENDIX-C.

(1) Fill

(2) Sandy Clay

(3) Marine Clay

(4) Silty Clay

(5) Silty Sand

6

(1) Fill

From the surface up to the depth of 2.5 to 3.0 meters, was covered with back

fill soil mixed with hardcore materials.

(2) Sandy Clay

This layer represents the Alluvial Member of Kallang Formation. It consists of

very soft to hard, yellowish grey to yellowish brown, Sandy Clay with organic

remains and rock fragments. Thickness is about 4.0 to 9.0 meters. SPT values ranged

from 2 to 50 blows. The other layer at the base of BH-1, was hard, light yellowish

brown, Sandy Clay with fine gravels. Thickness can not be estimated as the bore hole

terminated in this layer. SPT values showed 100 blows.

(3) Marine Clay

This is a Marine Member of Kallang Formation. It can be seen only in BH-1.

It consists of very soft, bluish grey to grey, Marine Clay, with organic remains.

Thickness is about 2.5 meters and SPT value registered at 2 blows.

(4) Silty Clay

This soil type represents the Old Alluvium. Being interbedded with marine

clays, it consists of firm to hard, light yellow, purplish brown, mottled with red, Silty

Clay. Thickness is about 6.0 to 11.5 meters and SPT values ranged from 6 to 100

blows.

(5) Silty Sand

This is a representative of an Old Alluvium. It consists of very dense,

yellowish to reddish brown, Silty, fine Sand. Thickness is about 9.0 meters, but can

not estimate the true thickness as the bore holes terminated in this layer. SPT values

showed 100 blows.

7

General Geology

Based upon the Geological Map of Singapore by PWD (1974) and the present

investigation, [Sandy Clay] from Alluvial Member and [Marine Clay] from Marine

Member of 'Kallang Formation', followed by [Silty Clay] [Silty Sand] of 'Old

Alluvium', are well distributed at the project site.

3.2 Laboratory Tests

Summary of laboratory test results and details of individual test results are

shown in the APPENDIX-D.

APPENDIX - A

TABLES & CHARTS

CLIENT : URBAN REDEVELOPMENT AUTHORITYPROJECT : MOHAMMED SULTAN ROADTABLE 1. : SUMMARY ON QUANTITY OF FIELD INVESTIGATION

Mech-anic

(Nos)

Hydro (Nos)

UU* (Nos)

CIU* (Nos)

BH 1 03/07/06 04/07/06 - 21.45 21.45 - 7 5 2 2 2 - - - - 2 - - - -BH 2 01/07/06 03/07/06 - 21.10 21.10 - 7 5 1 1 1 - - - - 1 - - - -BH 3 30/06/06 03/07/06 - 18.03 18.03 - 6 5 2 2 2 - - - - 2 - - - -

60.58 60.58 0.00 20 15 5 5 5 0 0 0 0 5 0 0 0 0Note :SPT = Standard Penetration Test UD = Undisturbed Sample CU = Consolidated Undrained Triaxial TestDS = Disturbed Sample UU = Unconsolidated Undrained Triaxial Test

pH (Nos)

SO3

(Nos)CL-

(Nos)

Reduce Level (m)

Total Depth

of Bore Hole (m)

Period of Fieldwork

SPT(Nos)

Insitu Test & InstallationChemical Test

Bore Hole No.

Physical Test Mechanical TestTriaxial Tests

Laboratory Test

Grain Size

Commence CompleteAtter-berg Limit (Nos)

Specific Gravity (Nos)

Bulk/Dry Density (Nos)

Moisture Content (Nos)

Depth of Drilling in Soil

(m)

DS (Nos)

UD (Nos)

Depth of Coring in

Rock (m)

Client : Urban Redevelopment AuthorityProject : Mohammed Sultan Road

Location : Mohammed Sultan Road

TABLE 2. MONITORING RECORD FOR WATER LEVEL AT BOREHOLE (During Operation)

04/07/06 8:30 AM 9.00 2.20

02/07/06 8:30 AM 6.00 2.0003/07/06 8:30 AM 18.00 2.20

01/07/06 8:30 AM 6.00 2.2003/07/06 8:30 AM 18.00 2.20

Water Level (m)

Borehole Number Date Time Borehole Depth (m)

BH 1

BH 2

BH 3

APPENDIX - B

LOCATION PLAN

APPENDIX - C

BOREHOLE LOG

KEY TO BORING LOG

BORE HOLE LOG

( BH-1 to BH-3 )

GENERALIZED SOIL PROFILE

( CROSS _ SECTION )

APPENDIX - D

LABORATORY TEST RESULTS

Summary of Laboratory Test Results

SUMMARY OF LABORATORY TEST RESULTS

UCT

Borehole Sample Depth No. No. (m)

UD1 3.00-3.50 2.07 1.72 20 56 4

UD2 6.00-6.50 1.50 1.04 44 16 0

UD1 6.00-6.50 2.10 1.79 17 78 24

UD1 3.00-3.50 1.99 1.58 26 24 0

UD2 6.00-6.50 2.14 1.80 19 87 0

Client: M/s Urban Redevelopment Authority * Multi Stage UCT - Unconfined Compression Triaxial TestLocation: Soil Investigation at Mohammed Sultan Road ^ Field Vane UU - Unconsolidated Undrained Triaxial Compression TestJob No: URA000EPO06000465, Dated 25-04-2006 ~ Lab. Vane CIU - Consolidated Isotropic Undrained Triaxial Compression Test

CID - Consolidated Isotropic Drained Triaxial Compression TestC

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