Assume a soil mass with a level ground surface and a

material having a wet unit weight of 120 pcf. The vertical pressure at any

depth represents the major principal stress at that particular point. The

vertical pressure (stress) is the product of the soil unit weight and depth.

The lateral pressure acting at any point is one-half the vertical pressure and

represents the minor principal stress.

(a) Determine the principal stresses acting at a depth of 10

ft below the ground surface, and draw the Mohr’s circle for these conditions.

(b) What is the value of the maximum shear stress at this

depth?