Model tests on threshold energy for slope failure and associated case studies

Abstract

Following previous research finding that not only travel distances but also onsets of seismic-induced slope failure are uniquely determined in terms of energy, model tests on rigid blocks resting on deformable sand slopes have been conducted to clarify the uniqueness of failure initiation in terms of energy. Shaking table tests compared with static loading tests together with Newmark-type analyses indicate that the threshold energy for slope failure initiation is governed by the deformability of slopes before peaks of load versus deformation curves. A simple formula for the threshold energy in evaluating initiations of non-rigid type slope failures has been developed based on the model test findings and applied to two actual failed slopes witnessed by local people during a recent earthquake. It has been demonstrated that evaluated threshold energies are mostly compatible with seismic pulse energies available at the slopes if critical shear strain for failure initiation is assumed to be 3-6% for slope friction angles larger than initial slope angles by 1-10°.