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An over-consolidated clay soil deposit was found to have the following parameters: M = 0.70, 1 = 0.22, N = 3.65, and I = 3.10. (a) A sample of this soil was isotropically consolidated under cell pressures of 100 kPa, 200 kPa, and 400 kPa. Calculate the mean principal stress at failure, the major principal stress at failure, the deviatoric compression stress at failure and the ultimate voids ratio if the deviatoric compression stage of the test was drained. (10 marks) (b) Sketch, and annotate where appropriate, the stress paths in p’ — a space for the three drained tests analysed in Q3(a) and show the critical state line on your sketch. (10 marks) (c) Explain the usefulness of the stress paths sketched in Q3(b) in comparison with the Mohr-Coulomb (1 – 0) stress space representation more conventionally plotted in the form of Mohr’s circles of stress.