Seismic Passive Resistance of Cohesive-Frictional Soil Medium: Kinematic Limit Analysis

Abstract

In the present study, extensive theoretical solutions in the form of charts have been generated based on a kinematically admissible translational mechanism for computing the passive resistance of cohesive-frictional soil retained by a rigid wall due to seismic body forces. With the application of the upper bound limit theorem of plasticity, the analysis was performed in the framework of a pseudostatic approach on an assumed composite collapse mechanism. This collapse mechanism comprises a radial shearing zone sandwiched between two triangular blocks, in which a new kinematically admissible velocity field is introduced, which provides upper bound values less than that computed by using the conventional logarithmic spiral and circular shearing zone reported in the earlier studies. The results are presented in terms of dimensionless passive earth-pressure coefficients due to the contribution of soil cohesion, surcharge, and unit weight of soil. The pseudostatic seismic forces do not affect the passive earth-pressure coefficients corresponding to the soil cohesion component; however, the passive earth-pressure coefficients, because of the soil unit weight and surcharge pressure, reduce considerably as the coefficients of seismic acceleration increase. Moreover, the reduction in passive earth-pressure coefficients is largely influenced by roughness, orientation of wall, slope angle of backfill soil, and the position of surcharge from the wall.