A laboratory oedometer test is performed on a clay specimen, with a thickness of 100 mm and a coefficient of consolidation Cy of 1.0 mp/year: the oedometer is drained on its upper and lower surfaces. The specimen is subjected to a uniform pore water pressure distribution ranging from 100 kPa at the start of consolidation to 200 kPa in step-wise increments of 50 kPa per hour. Using a finite difference approximation to the one-dimensional consolidation equation, estimate the pore water pressure u at the mid-height (i.e., z = 50 mm) of the specimen after a time t of four hours and estimate the degree of consolidation within the layer.
