The problem is a slope stability problem to be solved using block analysis method.
Slope Stability
Question: Solve using block analysis method
A thin seam of sand lies inclined at an angle of 20° and intersects the base of a cliff. The drainage of the sand is stopped by accumulated talus. The sand is overlaid by rock mass of 70 ft. thick. The ground surface slopes at 60° (with the horizontal), and there is a deep vertical crack extending through the rock 65.5 ft. from the face of the cliff. The unit weight of rock is150 pcf and the angle of internal friction of the sand is 40°. How high must the water rise in the sand before the block of rock slides upon the sand layer?
