3 URBAN REDEVELOPMENT AUTHORITY TERM CONTRACT FOR SOIL INVESTIGATION (URA/T/13/010) Soil Investigation Works At Sungei Tengah Agrotechnology Park CONTENTS VOLUME I Page No. 1.0 INTRODUCTION 005 1.1 General 005 2.0 FIELD WORKS 006 2.1 General 006 2.2 Description of Field Investigation 006 2.2.1 Drilling 006 2.2.2 Undisturbed Sampling 006 2.2.3 Standard Penetration Testing 006 3.0 LABORATORY TESTING 007 3.1 General 007 3.2 Code of Practice 007 3.3 Physical Properties 007 3.3.1 Moisture Content 007 3.3.2 Bulk and Dry Density 008 3.3.3 Atterberg Limit 008 3.3.4 Grain Size Analysis 008 3.4 Mechanical Properties 008 3.4.1 Unconsolidated Undrained (UU) Triaxial Test 008 3.5 Summary of Laboratory Test Results for Soils 009 4.0 SOIL CLASSIFICATION 009 5.0 LIST OF GEOLOGICAL CROSS-SECTIONS 011 REFERENCES 012 LIST OF TABLES Table 1.1 Quantity of Field Works and Laboratory Tests 013 Table 2.1 Classification / Symbol of Soil and Rock Type 014 Report No: ECGP 2531 URA ECON GEOTECH PTE LTD 4 URBAN REDEVELOPMENT AUTHORITY TERM CONTRACT FOR SOIL INVESTIGATION (URA/T/13/010) Soil Investigation Works At Sungei Tengah Agrotechnology Park Table 2.2 Geological Stratigraphy of Singapore 015 Table 2.3 Identification and Description of Soils 016 Table 2.4 Weathering Classification of Soils / Rocks 018 Table 2.5 Plasticity Chart 019 Table 2.6.1 Classification of Clays/Silts from Shear Strength 020 Table 2.6.2 Classification of Clays/Silts from SPT results 020 Table 2.6.3 Classification of Sands from SPT Results 020 LIST OF FIGURES Fig. 1 Illustration of Boring Work 021 Fig. 2 Illustration of Standard Penetration Test 022 APPENDICES APPENDIX A · Location Plan 024 · Borehole Location Plan 025 · As-built Borehole Locations 026 · Cross-Sections 027 · Legends for different soil and rock types 028 · Borehole Logs 029-036 APPENDIX B · Laboratory Test Results of Physical & Mechanical Properties of Soil Samples 038-097 · Certificate of Accreditations 098 aõb Report No: ECGP 2531 URA ECON GEOTECH PTE LTD 1.0 INTRODUCTION 1.1 General On behalf of Urban Redevelopment Authority, Econ Geotech Pte Ltd has performed the Contract URA/T/13/010 Site Investigation Works at West Coast Vale. The field investigation for this project was carried out between 26th March 2015 and 2nd April 2015. The works described in this report have been carried out as per the specifications and under the technical direction of the client. This report presents the soil investigation based on 3 boreholes. The particulars of this project are as follows: (a) Name of Project Site Investigation Works for Contract URA / T/13/010 (b) Location West Coast Vale (c) Client URBAN REDEVELOPMENT AUTHORITY (d) Main Contractor ECON Geotech Pte. Ltd. (e) Director Steven Ih Yeo (f) Project Manager Aung Moe (g) Period of Work Field Works 26th March 2015 – 2nd April 2015 Laboratory Works and Report 4th April 2015 – 21st April 2015 (h) Scope of Work Field Works Ø Boreholes 4 Locations Ø Laboratory Tests Water Content, Bulk & Dry Density, Atterberg Limit Tests, Triaxial (UU) Tests, Mechanical Analysis (Refer Table 1.1 & 1.2 for Quantities of Field and Laboratory Works) 5 2.0 FIELD WORKS 2.1 General The field works were carried out in accordance with BS 5930: 1999 “Code of Practice for Site Investigation” and / or as directed by the client. The Borehole Location Plan for proposed site investigation works is shown in Appendix-A. The as-built coordinates and reduced levels of the boreholes are also presented in respective borelogs in Appendix-A. 2.2 Description of Field Investigation 2.2.1 Drilling This investigation was performed using rotary drilling rig. A cutting tool was attached to the drilling rod to drill through the soils, which produces 100mm diameter borehole. Circulated mud water was pumped through the hollow rods into the hole to stabilize the borehole and to wash out the soil debris (resulted due to drilling) to the ground surface by pressure. Partial casing (100mmф) was used to stabilize the soil on top in the borehole apart from using mud circulation. Trial pits of size 1.0 x 0.8 x 1.0 m depth was dug manually at every borehole locations. The boreholes were terminated at the depths as suggested by the client. Illustration of boring works was shown in (Fig.2.1) During the investigation, a site bore log was done and kept by the geotechnical site supervisor to note down soil descriptions, stratum changes, SPT and coring field records. 2.2.2 Undisturbed Sampling Undisturbed samples (UD samples) were collected at the depth of 2m interval in Kallang Formation and 3m interval in OA (Old Alluvium) and other formations, unless specified by the client. Before a sample was taken, the bottom of the borehole was properly cleaned. Each sample was then collected using a 75 mm diameter by 1000 mm long thin wall sampler tube driven by hydraulic push. Samples of very stiff to hard soil were collected by using Mazier sampler. Thin wall piston samplers were used for very soft to soft soil. After a sample was retrieved from borehole, it was immediately labeled and sealed with wax at both ends before sending to laboratory. 2.2.3 Standard Penetration Testing Standard Penetration Tests (SPT) is performed at 3.0m interval in all soil layers, except in the Kallang Formation. In Kallang Formation, the SPT is conducted at 2m interval. Once the borehole reached the required test depth, the borehole was cleaned by flushing with 6 water/mud before starting the test. The test was performed by using a split barrel type sampler with a 50.8 mm external and 34.9 mm internal diameter. The test was conducted in six stages, where each stage consisted of driving the sampler 75 mm into the soil by using a free fall of 63.5 kg hammer (or monkey). The hammer was dropped from a height of 760 mm on to anvil connected to the sampler by rods. The number of blows required for each 75mm penetration was noted and the final N-value is reported as the total number of blows required to achieve the last 300 mm of penetration, the initial 150 mm of penetration being to seat the sampler and by-pass any disturbance. If, however, 100 blows were reached before a penetration of 300 mm was achieved, the test was stopped and the penetration achieved recorded. 3.0 LABORATORY TESTING 3.1 General The various laboratory tests were performed on undisturbed samples based on the testing schedule approved by the alient/consultant. The tests related to mechanical properties were performed in the Econ Geotech Laboratory. The quantities of laboratory tests are summarized in Table 1.2 3.2 Code of Practice The laboratory tests were performed in accordance with the British Standard Code of Practice BS 1377 (1990) and as per terms of accreditation under the Singapore Accreditation Council – Singapore Laboratory Accreditation Scheme. The summaries and detailed test results are presented in Appendix-B. The results are also presented in respective borehole logs. 3.3 Physical Properties 3.3.1 Moisture Content To measure moisture content, a weighed specimen is taken from an undisturbed sample and placed in a tin, where it is oven dried at 105-110◦C for 18-24 hours. The soil is weighted after the drying and the weight of water is calculated simply by subtracting the two values. The moisture content is then defined as the percentage of the weight of water over weight of dry soil. 7 3.3.2 Bulk and Dry Density The bulk density is the measured weight of a solid cylindrical soil specimen taken from an undisturbed sample divided by its volume. The dry density was calculated from bulk density and moisture content. 3.3.3 Atterberg Limit The liquid limit of a specimen is derived using the cone penetrometer method as to BS 1377. The plastic limit is defined as the moisture content of a specimen at the point where it can be satisfactorily rolled into a 3mm diameter thread with just starting to crumble. The soils’ plasticity index is then derived by subtracting the plastic limit from the liquid limit. 3.3.4 Grain Size Analysis The grain size analysis has been carried out utilizing both sieve and hydrometer analysis. The sieve analysis was carried out by wet sieving method in which the material was first washed through a 2 mm test sieve nested in a 63 mm test sieve. The soils retained in the sieves were then dried in an oven. The dried soils were then sieved by dry sieving by passing the soils through a series of square mesh sieves, which become progressively finer down to 63 mm mesh. Each fraction thus collected was then weighed and the percentage retained on each sieve was calculated by dividing individual weights by the total sample weight. The soils passing through 63 mm mesh was analyzed by sedimentation using hydrometer method. The hydrometer method involves measuring the rate of settlement of fine particles suspended in a solution. Utilizing the principle of Stokes’ law, particle size can be directly related to its rate of settlement in a fluid such as water. From this process, the particle diameter and percentage finer is calculated. 3.4 Mechanical Properties 3.4.1 Unconsolidated Undrained (UU) Triaxial Test This test is generally performed as a set of three single stage tests (UU). However, if the sample is not enough, the test is conducted using two or single (multistage) specimen.