A cylindrical soil sample was taken from a borrow pit and measured as below: Dimensions of sample: Diameter = 50 mm; Length = 100 mm Initial mass of sample: 336.5 g Mass of sample after drying: 292.6 g The soil from the borrow pit is to be used as compacted backfill in a trench with 100m in length, 500mm in width, and 1500 mm in thickness. The soil is to be compacted into the trench with a total unit weight (γ_t) of 22 kN/m3 at a moisture content of 9%. Determine the volume of the soil required to be excavated from the borrow area in order to provide sufficient fill for the trench. Question 3 A soil profile at a site of partially buried steel water tank having a diameter of 35m consists of dense sand up to 10m depth, soft clay from 10m to 14m, and below 14m depth is an impervious rock. The groundwater table is at 2m depth below the ground level. The sand has a unit weight of 18.2kN/m3 above the water table and 19 kN/m3 below the water table. Tests on a sample taken from the mid-depth of the clay layer give a moisture content of 25%, the liquid limit (LL) of 65% and a specific gravity of 2.7. UTS: 49118 Applied Geotechnics 2015 Construction of the tank will initially involve lowering the water table to a depth of 8m, excavating 7m of sand and placing the tank. Then, the steel tank is filled with water as illustrated in the following figure. Knowing that the compression and recompression indices can be computed from ( ) and , and the preconsolidated pressure ( ) is 150 kPa, determine the thickness of the clay layer a long time after construction if: (a) The water table is permanently maintained at the lower level. (b) The water table is allowed to rise back to its original position after construction.

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