Fourth-Ave-Soilrpt.Pdf
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CONTENTS Page 1. GeneralsG 4 2. Field Investigation WorkG 4 3. Laboratory Testing Work--- 5 4. Surface Soil Description-- 7 Appendix A Borehole Location Plan 11 Soil Profile-- 15 Bore Logs--=---- 18 Appendix B Quantity of Field Works and Laboratory Tests 28 Laboratory Test Summary-- 30 Result of Laboratory Testing Works 32 Appendix C SPT Vs Depth--- 60 Calibration of SPT Hammer Energy Ratio ( Er )- 62 3 1. General Cast Laboratories Pte Ltd was engaged by Urban Redevelopment Authority, Soil investigation Works at Fourth Avenue. The soil investigation works comprised drilling of (3) boreholes with associated undisturbed sampling, disturbed sampling and necessary in- situ testing as well as laboratory testing. The purpose of the investigation was to obtain geotechnical information on the subsoil conditions at the site. The field investigation for drilling of boreholes was conducted at 3 April 2017 to 15 April 2017. Laboratory tests were conducted on selected soil samples in Cast Laboratories Pte Ltd. 2. Field Investigation Work Trial pit by manually followed hand auger up to 3.0m depth was conducted at each borehole in order to avoid damage to underground utilities services. Bore holes with the nominal diameter of 100 mm were drilled using TOHO rotary drill rigs. 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 stabilize the borehole and wash out the cuttings to ground surface. Partial casing was used to stabilize the borehole side apart from using mud circulation. Thin-walled undisturbed push samples were collected from the soft to stiff cohesive soil layers by pushing a 76 mm-diameter thin-walled sampling tube into the soil by the static thrust of the drilling rig. Upon removal of the tube from the borehole, the tube was cleaned and both ends of the tube sealed with paraffin wax immediately. SPT's were being performed to determine the relative density or consistency of soils and to obtain soil samples for visual classification. A standard split barrel sampler of 50mm outer diameter was lowered to the bottom of the borehole on drill rods. The sampler was then driven 450mm into the soil by a 63.5kg self - tripping hammer free falling from a height of 760mm. The blow counts required to advance the final 300mm of a 450mm sampler drive was recorded on the borehole logs as SPT ‘N’ values. In dense strata where it was difficult to drive the sampler the full 450mm, the 4 penetration achieved beyond the initial 150mm seating drive with 100 blows of the hammer was recorded instead. After inspection, the recovered samples were placed in double polythene bags for soil identification. 3. Laboratory Testing Work The undisturbed samples were extruded from their sampling tubes, examined and visually classified. The laboratory testing work was set up to identify the soil strata adequately, and the strength and deformation properties of the subsurface soils for foundation design. All samples were examined by a soil lab technician and checked against the laboratory test results before the final description. Basically, the lab testing work is consisting of two main groups as below: (I) Classification Test • Moisture content and Bulk and Dry Density • Atterberg limits, Particle Size distribution by sieving (II) Strength Tests • Uconsolidated-Undrained (UU) triaxial compression test --• Direct Shear Test (I) Classification Test Moisture Content, Bulk and Dry Density 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. 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/m3, which is numerically the same as g/cm3. 5 Atterberg Limits Test The Atterberg limits refer to arbitrarily defined boundaries between the liquid and plastic states (ie, liquid limit, WL) and between the plastic and brittle states (ie, plastic limit, WP), of fine grained soils. They are expressed in percentage water content. The range of water contents over which a soil behaves plastically is termed the Plastic Index and corresponds to the numerical difference between the liquid and plastic limit (ie, WL-WP). Tests to determine the Atterberg limits can be performed on soil samples of cohesive material. The soil is dried and then ground into separate grains using a mortar. The soil grains larger than 425m size are removed by sieving. The soil is then thoroughly mixed with different quantities of distilled water. Particle Size Distribution (Sieve Analysis) Particle size distribution is determined by means of sieving, hydrometer tests, or both. The percentage of weight of the various particle sizes in excess of 63m is determined by sieving through a set of standard sieves. When there is a considerable amount of particles smaller than 63m, the sieving is complemented by a hydrometer test in which the sample is mixed with water and stirred for about 15minutes. An additive prevents flocculation of the soil particles. After mixing, the density of the water-soil slurry is measured at fixed time intervals, and the particle size distribution of the sediment particles can be determined. (II) Strength Tests Unconsolidated-Untrained (UU) Triaxial Compression Test This test is performed on undisturbed samples of cohesive soils. The test specimen - 38mm in diameter and 76mm in height - is prepared by trimming. A rubber membrane is placed around the specimen and a confining pressure is applied to the sample. During the axial loading of the specimen, the confining pressure is kept constant and drainage of pore water is not allowed. The test is continued until the specimen shears and a peak value is obtained, or until 20 percent strain has occurred. The results of the tests are presented as deviator stress versus axial strain. The undrained shear strength, defined as half the ultimate deviator stress, can be derived from these presentations and is reported to the nearest whole kPa. 6 Direct Shear Test Direct Shear box test is performed to determine the shear strength of soil. A specimen is placed in a circular shear box which has two split rings to hold the sample and the contact between the two rings is horizontally around the mid-height of the sample. Porous plates are used to allow free drainage. A vertical force (N) is applied to the specimen through a loading plate and shear stress is gradually applied on a horizontal plane by casing the two halves of the box to move relative to each other, the shear force (T) being measured together with the corresponding shear displacement. 4. Subsurface Soil Description The entire area under site investigation works is underlain by KALLANG FORMATION (Fluvial and Transitional) and BUKIT TIMAH GRANITE (Residual Soil, Completely Weathered, Highly Weathered, Moderately Weathered and Slightly Weathered) which in turn is overlain by unit of under FILL layer. The surficial unit is made up of FILL (made to ground by man). The following geological map shows the geological setting of the area. ` Geology and Site Vicinity Map of Soil Investigation Works At Fourth Avenue 7 References 1. BS 1377:1990 – “Code of Practice for Laboratory Tests”, “Methods of Test for Civil Engineering Purposes”. 2. Geology of Singapore by PWD (1976) and DSTA (2009) 3. SS EN 1997 - 2 (2010), “Ground Investigation and Testing”. 4. BS EN 22475 - 1, “Drilling, Sampling and Ground Water Measurement”. 5. BS EN 22476 - 3, “The Calibration of SPT Hammer Energy Ratio (Er)”. 6. BS EN 14688, “Identification and Classification of Soil”. 7. BS EN 14689, “Identification and Classification of Rock”. 8 9 10 BH‐3 BH‐2 BH‐1 LEGEND BOREHOLE LOCATION PLAN OF FOURTH AVENUE Borehole 11 VANDA LINK VANDA ROAD VANDA DRIVE VANDA DRIVE DUNEARN ROADTURF CLUB ROAD BUKIT TIMAH ROAD Sixth Avenue MRT Station (DT7) Sixth Ave (Underground) Centre ENG NEO AVENUE VANDA ROAD JALAN NAGA SARI SIXTH AVENUE ANAMALAI Guthrie MRT entrance/ exit structure SIXTH AVENUE House CANAL AVENUE FIFTH AVENUE LILY AVENUE PUB Pipeline Reserve LAND FIFTH PARCEL AVE Second LEMON AVENUE Avenue SIXTH CONDO Junction AVE VILLE FOURTH AVENUE SIXTH AVENUE FIFTH AVENUE THIRD AVENUE SECOND AVENUE THIRD AVENUE FIRST AVENUE L O C A T I O N P L A N S C A L E : 1 : 5 0 0 0 12 SIXTH AVENUE FIFTH AVENUE BUKIT TIMAH ROAD TIMAH BUKIT FIFTH AVENUE CANAL B O R E H O L E L O C A T I O N P L A N S C A L E : 1 : 2 0 0 0 DUNEARN ROAD DUNEARN FOURTH AVENUE THIRD AVENUE 13 14 Borehole Terminated at 34.33m Borehole Terminated at 43.30m BH-1 & BH-2 GEOLOGICAL CLASSIFICATION KALLANG FORMATION OLD ALLUVIUM JURONG FORMATION BUKIT TIMAH GRANITE VERTICAL SCALE - 1:400 Drawn By : Ng How Yong Date:24-Apr-2017 HORIZONTAL SCALE - NOT TO SCALE URBAN REDEVELOPMENT AUTHORITY SOIL INVESTIGATION WORKS AT FOURTH AVENUE 15 Borehole Terminated at 43.30m Borehole terminated at 46.32m BH1 & BH-3 GEOLOGICAL CLASSIFICATION KALLANG FORMATION OLD ALLUVIUM JURONG FORMATION BUKIT TIMAH GRANITE VERTICAL SCALE - 1:400 Drawn By : Ng How Yong Date: 24-Apr-2017 HORIZONTAL SCALE - NOT TO SCALE URBAN REDEVELOPMENT AUTHORITY SOIL INVESTIGATION WORKS AT FOURTH AVENUE 16 17 Trial Pit(1.0 x 0.8 x