QUESTION A.
A soil sample for new development of Hospital Parity Bunter was collected for laboratory test.
The soil sample has a wet mass of 5.1 kg, bulk density of 1.63 g/cm3 , dry density of 1220 kg/m3 and degree of saturation of 78%. From the information given
- Draw the 3-phase diagram of the unsaturated soil sample by deriving the equations of weight-volume relationships for each of the soil phase (Assumed Vs = 1)
- Determine the density of solids.
- Describe the main difference between the dry density and density of solids and give a typical range of values for both.
- Explain why high plasticity soil can hold so much water compared to the coarse-grained soil.
QUESTION B.
Complex Problem-solving question sections (field application)
Soil excavated from a borrow pit at another site is being used to construct an embankment (Fig. below). The soil sample from the borrow pit has a specific gravity of 2.7 and unit weight of 17.8 kNm−3. The weight of the sample was 3.5 N. The sample was then placed in an oven for 24 h at 105°C and its weight reduced to a constant value of 2.9 N. The soil at the embankment is required to be compacted to a void ratio of 0.71. If the finished volume of the embankment (Ve) is 80,000 m3 , what would be the volume of the soil (Vb) excavated at the borrow area? (Assume volume of solids (Vs) is equal to 1)
