For walls that retain cohesive soils and are free to move a considerable
amount over a long period of time, the total thrust from the soil (assuming a
level surface) is

P = ½ g H²K_A – 2 c H K_A^1/2

or, because highly cohesive soils generally have small angles of internal
friction,

P = ½ g H²- 2 c H

The thrust is applied at a point somewhat below H /3 from the bottom of the
wall, and the pressure distribution is approximately triangular.

For walls that retain cohesive soils and are free to move only a small amount
or not at all, the total thrust from the soil is

P = ½ g H²K_P

because the cohesion would be lost through plastic flow.