Seismic Elastic Response of Earth Dams with Canyon Interaction

Abstract

This paper deals with the seismic response of earth and rockfill dams, using elastic models that consider the deformability of the surrounding medium and effects of spatial variation of the seismic excitation. A finite-element-based method has been developed in which the dam is idealized as a shear beam and the surrounding medium as a halfspace. The model can simulate canyons of arbitrary shape, oblique SH-wave seismic excitation, and inhomogeneous distribution of elastic and damping properties of the dam and the surrounding medium. The methodology is illustrated by simulating the upstream-downstream response of the La Villita Dam, an earth and rockfill dam located near the epicenter of the 1985 Mexico earthquake, for various conditions of the surrounding foundation material. Results show that for models that include both foundation flexibility and radiated energy, the earthquake response of the dam is, overall, only a fraction of that obtained under the assumption of a rigid canyon. Exploiting these results may have a potentially beneficial effect in the retrofit of existing dams and design of new ones.