Earth Dam‐Canyon Interaction Effects for Obliquely Incident SH Waves

Abstract

Dam‐canyon interaction effects on the response of earth and rockfill dams built in narrow canyons are considered. An analytical closed‐form solution is used for a dam in a semicylindrical canyon, subjected to obliquely incident harmonic SH waves. The dam is idealized as linearly hysteretic elastic body deforming only in shear, while the canyon is modeled as an elastic half‐space. The model accounts in a rigorous way for the wave reflection and diffraction phenomena caused by the presence of the dam‐canyon system. It is shown that the motion amplification is considerably less for a dam in flexible canyon than for a dam in a rigid canyon and that the effects of radiation damping and asynchronous base motion may be very important. For oblique SH waves, the presence of antisymmetric terms in the solution may lead to response substantially higher than that induced by vertically propagating waves. Finally, as the canyon narrowness increases, the amplification at higher frequencies increases significantly for a rigid base, but it may decrease for a flexible base.