Nonlinear Seismic Response of Earth Dams with Canyon Interaction

Abstract

This paper examines the nonlinear earthquake response of earth dams, using a model that considers 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. Nonlinear behavior of the dam is modeled using multiyield surface plasticity theory. The model can simulate canyons of arbitrary shape and SH-wave seismic excitation. The methodology is illustrated by simulating the upstream–downstream earthquake response of La Villita Dam, which is located near the epicenter of the 1985 Mexico earthquake. Results show that the reduction in the response that occurs as a result of dam-canyon interaction remains significant when the inelastic deformation of the dam is included in the model, and that when examined in the frequency domain, nonlinearity has radically different effects at low, medium, and high frequencies of excitation.