EARTHQUAKE-INDUCED BASE SLIDING OF CONCRETE GRAVITY DAMS

Analytical procedures are developed considering hydrodynamic effects to determine the response history of earthquake-induced sliding of a gravity dam monolith supported without bond on a horizontal, planar surface of rock. The results presented indicate that the permanent sliding displacements of dams induced by ground motions with peak acceleration of 0.5 g may range from a few inches to a couple of feet. Also examined in this work is the possibility of estimating the sliding displacement of a flexible dam due to ground acceleration by analyzing the sliding response of a rigid dam due to an average (over height) acceleration computed from linear analysis of the flexible dam without sliding at the base. The results presented indicate that this approximate procedure, which has been widely used in estimating the deformations of embankment dams, can provide an order-of-magnitude estimate of the concrete dam sliding displacement, which is conservative for most cases when this displacement is practically significant.