On the basis of coulomb’s concept that the earth pressure against the back of a retaining wall is due to the thrust exerted by a sliding wedge of soil between the back of the wall and a plane which passes through the bottom edge of the wall and has an inclination of

the differential equations of first order are set up by considering the equilibrium of the forces and the moments on an element of the wedge. The lateral coefficient of earth pressure

the unit earth pressure

the resultant force of earth pressure and the application point of the resultant force are obtained. The effects of the internal frictional angle of backfill and the frictional angle between the wall back and the backfill on the lateral coefficient of earth pressure

the unit earth pressure

the resultant force of earth pressure

the application point of the resultant force and the overturning stability of a retaining wall are investigated.