Problem: A soil sample is subjected to a tri-axial test where the measured hydrostatic stress is 450 kPa; the applied deviator stress is 460 kPa; and the measured water pressure is 80 kPa. The soil has material properties of cohesion of 80 kPa and the internal angle of friction of 23 degrees. Determine:
Part A: Angle of the failure plane.
Part B: Principal normal stress.
Part C: Principal shear stress.
Part D: Effective normal stress.
Part E: Shear strength.
Rework your solution from the beginning and check each step carefully.