1. (a) In order to compensate for the many uncertainties in foundation analysis and design, engineers use factors of safety. The factor of safety defines the engineer's estimate of the best compromise between cost and reliability.
Describe five (5) of the factors affecting the engineer's choice of factors of safety.
(b) Explain the difference between site investigation and ground investigation.
(c) Soil mechanics differs from other forms of mechanics due to the special characteristics of soils. Describe three (3) of these special characteristics which are different from those of other materials such as concrete and steel.
(d) To determine the properties of a clay soil, a sample was taken from a sample tube of a volume of 3.22 x 10-3 m3. The following had been determined:
Mass of empty tube = 3.70 kg
Mass of tube + clay sample = 10.04 kg
Mass of tube + clay sample after oven drying = 8.70 kg
If the specific gravity of the clay sample is 2.70, calculate the following:
(i) void ratio (e)
(ii) porosity (n)
(iii) dry density ( rd)
(iv) water content (w)
(v) degree of saturation (S)