An important and essential part of the design of retaining walls consists of determining
the earth pressure on the back of the wall. The earliest theory of earth pressure
traces back to Charles-Augustin de Coulomb, who published his work in 1773.
Coulomb’s theory presented a method by which a designer could determine the pressure
that dry, granular, cohesionless material would exert upon the back of a wall constructed
to restrain the material. His work was based on the theory that failure is characterized
by a wedge-shaped mass of the supported sand material that slides down along a sloping
plane such as is shown in Fig. 8.6