= -1 =

Example 5.9 A large excavation is made in a stiff clay whose saturated unit weight is 109.8 Ib/ft3. When the depth of excavation reaches 24.6 ft, cracks appear and water begins to flow upward to bring sand to the surface. Subsequent borings indicate that the clay is underlain by sand at a depth of 36.1 ft below the original ground surface.