can you solve the all partsA sand sample was isotropically consolidated under $300$kPa effective stress in a

triaxial test device. Then, it was sheared under constant cell and pore pressure. At

failure, deviator stress $({}_1-{}_3)$ was $807$kPa.

a$)$ Determine the principle stresses at failure, draw Mohr circle for effective stress at

failure, and determine the angle of shearing resistance $($i$.$e$.,$ friction angle$)$ of the

soil.

b$)$ The same sand was also tested in a direct shear apparatus under a normal pressure

of $300$kPa. Predict the peak shear stress. Also draw the Mohr circle and determine

the magnitude and direction of principle stresses at failure.