Abstract: The movement of wall plays an important role in the calculation of lateral earth pressure and the design of retaining structure. Regarding the process of backfill approach active or passive pressure state as the shearing process of soil sample in simple shear test or direct shear test, the backfill process reaches active or passive earth pressure state when the soil deformation equals to the ultimate value (shear strain in the simple test or shear displacement per unit length in the direct shear test). Based on the geometric relationship between the soil shear deformation and wall displacement, the theoretical calculation method of wall displacement required to reach active or passive earth pressure is provided, where the soil stress-strain behavior and initial stress state are considered. The analysis indicates that the magnitude of needed wall displacement to reach active or passive earth pressure is controlled by soil ultimate shear deformation, the range of active or passive zone, and the initial earth pressure state. The first factor is the most important among them, which contributes to variation of wall displacement among different soils. The wall displacement in passive state is greater than that in active state, because the range of passive zone is larger than that of active zone. The theoretically calculated wall displacement attaining active state is about 0.5‰~13.2‰ H (where H is the height of the wall), of which the non-cohesive soil is larger than the cohesive soil. As to the case of passive state, the wall displacement is ?0.4%~?5.2% H. The theories are concordant with the model test results from relevant literatures.

Key words: active or passive earth pressure state, displacement of wall, Rankine and Coulomb earth pressure theories, soil ultimate shear deformation, simple shear test, direct shear test