Abstract: The classical Rankine's earth pressure theory, despite its convenience, neglects the influence of soil's friction angle and retaining wall's inclination on soil pressure, while Coulomb's earth pressure theory does not consider the cohesion of soil. To better reflect the change law of earth pressure behind retaining wall, a formula is derived based on Coulomb's earth pressure theory for cohesive soil. The friction angle between soil and wall, the height of tensile crack on the top of retaining wall, the displacement state of retaining wall, and the broken-line sliding surface are considered in the method. The effectiveness of the method for cohesive soil is verified by comparing theoretical calculations with model measurements. Compared with other theories, the proposed method is simpler and the calculated result is closer to measurements. The present formula can be simplified to Coulomb's formula of active earth pressure when cohesion is zero.

Key words: retaining wall, cohesive soil, active earth pressure, friction angle, limit state, sliding surface