Inclined Slice Method for Passive Earth Pressure on Rigid Walls Considering Interslice Shear Forces

The curved failure surface in the soil retained with a rigid wall is common if the soil is in the passive limit state. Based on the assumption that the critical slip surface is a log-spiral shape, the nonlinear distribution of the passive earth pressure along the wall height under static and seismic conditions was investigated using the inclined slice method and the pseudostatic approach under the wall rotating about its head. Meanwhile, the interslice shear forces were adequately taken into account with a limited mobilized coefficient related to the soil dilation angle and interslice shear strength. A general calculation method for the passive earth pressure was accordingly established and carried out using nonlinear multiparameter programming. The passive earth pressure was influenced by the backfill dilation angle, wall–soil friction angle, and seismic coefficients. In particular, the failure surface was developing from planar to curved surfaces with an increase of the wall–soil friction angle and the stress concentration of passive earth pressure at the wall heel was obvious except for the condition that the wall back is smooth or the soil dilation angle is relatively high. The proposed method could also be expanded to calculate the passive earth pressure of layered backfills.

This work provides a calculation method for passive earth pressure of single or layered backfill under seismic and static conditions, which holds practical significance for practitioners in geotechnical engineering related to soil lateral resistance against engineering structures such as reaction walls and bridge abutments. The proposed method can solve the distribution, resultant force, and its application point of the passive earth pressure and can be used for cohesionless and cohesive soil, inclined and rough wall back, and inclined backfill surface, which allows it to have a wide applicability. The analysis results demonstrate that the proposed passive earth pressures agree well with experimental values, indicating the accuracy and rationality of the proposed method. Moreover, it is found that some factors, such as backfill dilation angle, wall–soil friction angle, and seismic coefficients, significantly influence the distribution and magnitude of passive earth pressure. Some examples indicate that the profile of the passive earth pressure along the wall height takes on discontinuous characteristics with sharp variations at the interfaces between different backfills, which is beneficial for the optimization design of retaining walls.