Problem $11(15$ pts$)$

The failure critical state stresses and excess porewater pressures for each sample are given below.

A$)$ Plot Mohr's circle of effective stress for each sample

B$)$ Determine the friction angle for each test

C$)$ If the sand were to be subjected to a vertical effective stress of $300$ kPa $,$ what magnitude of horizontal effective stress will cause failure?

D$)$ Determine the orientations of the failure plane and the plane of maximum shear stress to the horizontal for Sample $\backslash$#$2.$

E$)$ For Sample $\backslash$#$1,$ determine the failure stresses

F$)$ Is the failure shear stress the maximum shear stress? Explain.