In a triaxial test, a soil specimen is allowed to consolidate fully under an all-round confining pressure of 200 kN/m2. Under undrained conditions the all-round pressure is increased to 350 kN/m2, the pore water pressure then being measured as 144kN/m2. Axial load is then applied under undrained conditions until failure takes place, the following results being obtained.

Axial strain (%) 0 2 4 6 8 10
Principal stress difference (kPa) 0 201 252 275 282 283
Pore water pressure (kPa) 144 211 228 222 212 209
Determine the value of the pore pressure coefficient B and determine whether the test can be considered as saturated. Plot the stress–strain (q–εs) curve for the test, and hence determine the shear modulus (stiffness) of the soil at each stage of loading. Draw also the stress paths (total and effective) for the test and estimate the critical state friction angle