The pressure versus void ratio data determined from a consolidation test on an undisturbed clay specimen are as follows:
Pressure (kPa) Void Ratio Pressure (kPa) Void Ratio
20 0.864 1280 0.602
40 0.853 320 0.628
80 0.843 80 0.663
160 0.830 20 0.704
320 0.785 0 0.801
640 0.696
a) Plot the pressure versus void ratio curve on a semilog graph
b) Determine CC and Cr
c) Estimate the stress at which this clay has been preconsolidated
d) If this samples was taken from 5 meters below the ground surface, estimate the OCR.