Kinematic Limit Analysis Approach for Seismic Active Earth Thrust Coefficients of Cohesive-Frictional Backfill

Abstract

A theoretical study has been performed for evaluating maximum resultant active force exerted by a cohesive-frictional backfill against a rigid wall with inclined back face undergoing outward horizontal translational movement in the presence of pseudostatic seismic loadings. With the application of a new kinematically admissible translational mechanism in the context of the upper bound limit theorem of plasticity, seismic active thrust has been derived as a function of nondimensional seismic active earth thrust coefficients because of the contributions of soil unit weight, surcharge pressure, and cohesion of soil. The present analysis was performed by postulating a composite collapse mechanism comprised of a central radial shearing zone enclosed between triangular blocks at either side. The kinematically admissible velocity field of the radial shear zone freely varies in between the velocity field used for defining the conventional circular to log spiral shear zones available in the literature. The influence of seismic acceleration coefficients, location of surcharge pressure from the wall crest, backfill slope angles, characteristics of interface between soil and wall, orientations of wall, and properties of backfill on the magnitude of active earth force has thoroughly been examined.