In the triaxial compression test, the application of additional axial stress (i.e. deviator stress) on the soil specimen produces shear stress on__________________?

A. horizontal plane only
B. vertical plane only
C. both horizontal and vertical planes
D. all planes except horizontal and vertical planes
✅ The correct answer is option D.

A cylindrical specimen of saturated soil failed under an axial vertical stress of 100kN/m2 when it was laterally unconfmed. The failure plane was inclined to the horizontal plane at an angle of 45°. The values of cohesion and angle of internal friction for the soil are respectively______________________?

A. 0.5 N/mm2 and 30°
B. 0.05 N/mm2 and 0°
C. 0.2 N/mm2 and 0°
D. 0.05 N/mm2 and 45°
✅ The correct answer is option B.