An office block with adjacent underground car park is to be built at a site where a 6 m thick layer of saturated clay ((y = 20 kN/m) is overlain by 4 m of sands and gravels ((y= 18 kN/m). The water table is at the top of the clay layer. The foundation for the office block will exert a uniform surcharge of 90 kPa at the surface of the sands and gravels. The foundation for the car park will exert a surcharge of 40 kPa at the surface of the clay, following removal by excavation of the sands and gravels. Calculate the initial and final vertical total stress, pore water pressure and vertical effective stress at the mid-depth of the clay layer: a). Beneath the office block. (10 marks) b). Beneath the car park. (10 marks) Take the unit weight of water as 9.81 kN/m.