A 9-m-thick layer of stiff saturated clay is underlain by a layer of sand.
The sand is under artesian pressure. Calculate the maximum depth of cut H that can be made in the clay.
Due to excavation, there will be unloading of the overburden pressure. Let the depth of the cut be H, at which point the bottom will heave. Let us consider the stability of point A at that time:
For heave to occur, should be 0. So: