Question

A soil sample was taken from the field and tested in the lab in drained triaxial conditions. If the soil failed at a major principle stress σ1 ’ = 130 kPa, and a minor principle stress σ3 ’ = 55 kPa:

a) What is the effective stress friction angle of the soil?

b) What was the shear stress at failure?

c) What was the normal stress at failure? Please using the Mohr circle to illustrate your answer.

Answer 1

(a) effective friction angle = 23.92 degree

(b) Shear stress at failure, S = 31.44 kpa

(c) Normal stress at failure = 70.88 kpa