Backfill Soil Cohesion Effect on Displacement of Rigid Retaining Walls Subjected to Earthquake

摘要

An analytical solution of seismic earth pressure is introduced into a theoretical model to evaluate the influence of the backfill cohesion on the permanent displacement of a rigid retaining wall. The wall is assumed to be a rigid body, and its motion equation is then derived by considering a coupled sliding-rocking movement mode. Nonlinear reaction of subgrade is simulated by means of the changing of dynamic modulus and damping ratio of foundation soil. The cohesive behaviour of backfill is performed in the analytical expression of seismic earth pressure. An acceleration time history is synthesized using the trigonometric series method, and is inputted into the model as an earthquake excitation. Permanent displacements are obtained under sixteen combined backfill conditions including four cohesions and four friction angles. The results show that the permanent displacement that the permanent displacement tends to decrease with the cohesion increasing. However, the decreasing range is negligibly small comparing with the decrease of the active earth pressure. It is therefore suggested that the effect of backfill cohesion on the permanent displacement should not be considered in the displacement-based seismic design of rigid retaining structures.