Damage characteristics and failure modes of concrete gravity dams subjected to penetration and explosion

Abstract

In recent decades, the penetration depth, hit accuracy, and damage ability of earth-penetrating weapons have been greatly improved. High dams will thus face increasingly severe threats of penetration and explosion from such weapons. The nonlinear dynamic responses and failure processes of dams under the combined action of penetration and explosion are much more complicated than those under static or seismic loadings, and they are yet more complex than those under air blasts or underwater explosion loads. There have been various comprehensive numerical investigations of concrete gravity dams subjected to underwater explosions; however, there have been few such investigations considering penetration and explosion. In this study, the damage characteristics and failure modes of a concrete gravity dam subjected to the combined action of penetration and explosion are examined. A fully coupled Lagrangian–Eulerian approach is adopted to describe the nonlinear dynamic responses and damage processes of the dam, and this includes consideration of the dam–reservoir–foundation interactions. In this paper, the validities of the penetration model and internal explosion model are discussed by comparing results obtained from the proposed method with those obtained from empirical formulas and experimental tests. The penetration characteristics of the concrete gravity dam subjected to impact by high-velocity projectiles are presented. The damage development processes and nonlinear dynamic responses of the dam to an internal explosion with and without consideration of the initial penetration damage are compared. The failure modes of the dam resulting from different penetration and explosion conditions are categorized. The penetration depths of different explosives resulting in the greatest damage range are obtained. The results show that although the initial penetration increases the degree of damage to the dam, it has little impact on the failure mode of the dam. The failure modes can be divided into two categories: a blasting funnel at the surface and an internal ellipsoidal explosion. The adverse penetration depth resulting in the greatest damage range is found to increase nonlinearly with increasing explosive weight.