Unformatted text preview: hydrostatic below this depth. 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; and (b) beneath the car park. Take the unit weight of water as 9.81kN/m 3 . Q1.4 Solution Initially, the stress state is the same at both locations. The vertical total stress σ v = (4m 18kN/m 3 ) (for the sands and gravels) + (3m 20kN/m 3 ) (for the clay), giving v = 132 kPa The pore water pressure u = (3m 9.81kN/m 3 ) = 29.4 kPa The vertical effective stress ' v = v- u = (132kPa - 29.4kPa) = 102.6 kPa Finally,...
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- Fall '11
- Analytical Chemistry, Aquifer, car park, Pore water pressure