Soil parameters for all cases: M=1.0, 0.2, k = 0.04, I = 3.14, N = 3.26, No = 3.21. 1.1 A "standard" triaxial compression test involves increasing the vertical stress (i.e. Aσv is +), while maintaining a constant horizontal stress (Aσ = 0), giving a stress path with a 3:1 gradient "Standard" undrained triaxial compression tests are carried out on 2 samples of a kaolin clay, prepared by isotropic consolidation from a slurry state. • Sample A: Normally consolidated to p' = 100 kPa •Sample B: Normally consolidated to p' = 500 kPa, and then unloaded isotropically to p' = 100 kPa. For each case, determine: (a) the (ultimate or critical state) undrained shear strength Su (SUA = 27.44 kPa; SUB = 99.4 kPa) (b) the excess pore water pressure (Au) at this stage (assuming the initial backpressure u, is zero). (UA = 63.41 kPa; UfB = -32.6 kPa) (c) Draw a sketch or sketches of the stress paths in q-p' and v-p' space for each case. 1.2 If drained compression tests (with the same "standard" stress path) had been carried out instead on the same two samples, determine: (d) the ultimate drained shear strength, Sd; and; (SdA = SdB = 75 kPa) (e) the volumetric strain due to shearing to this state. Indicate if volumetric strain is positive (compression) or negative (dilation). (A: +8.6% contraction; B: -2.7% dilation) 1.3 An alternative total stress path involves increasing the vertical total stress (Aσ, is +), while reducing the horizontal total stress by an amount equal to half of the increase in σ, (i.e. Aσ =-(A)). (This is not one of the stress paths dealt with in a previous tutorial). Assume that the back pressure u. = 0. (f) What is the gradient of this total stress path (i.e. what is Aq/Ap)? (vertical) (g) If this total stress path was applied to the two samples in 1.1 and 1.2, what would be the effect on: (i) the undrained shear strength su for samples A and B? (unchanged) (!!) the excess pore pressure Au at failure for samples A and B? (reduced from 63.41 kPa to 45.12 kPa for sample A; reduced from -32.6 kPa to - 98.9 kPa for sample B) (iii) the drained shear strength for samples A and B? (50 kPa for both)