CE 345 Prof. L.M. Star
Geotechnical Engineering I Spring 2016
Assignment 6:
Due March 14, 2016
1. The major and minor principal stresses at a point are 450 kPa and 200 kPa. Draw the
Mohr circle and compute the maximum shear stress.
2. An element of soil is subjected to the stresses shown in the Figure 1. Draw the Mohr
circle and find the pole. Calculate σ
a, σ
b
, and τ
ab, for an element of soil with the
orientation shown in Figure 2.
Figure 1 Figure 2
3. A soil profile consists of sandy soil with a total unit weight of 110 pcf above the
water table and 125 pcf below the water table. The water table is located at a depth
of 8 ft. Calculate the total vertical stress, the pore water pressure, and the effective
vertical stress at a depth of 17 ft below the soil surface.
4. Calculate σv, σ’v, σh
, σ’
h
, u and τ
vh, for point A in Figure 3. The coefficient of lateral
earth pressure is k=0.55. Draw the Mohr circle for both the total stress and the
effective stress cases.