Failure modes and effect analysis of concrete gravity dams subjected to underwater contact explosion considering the hydrostatic pressure

To better understand damage characteristics of concrete gravity dams under contact explosion is a critical issue to evaluate the protective performance of dams. In this paper, a fully coupled Lagrangian-Eulerian numerical approach, incorporating the detonation process of underwater contact explosion, is performed to predict the damage propagation of a typical concrete gravity dam. In order to verify the validity of the coupled algorithm, damage profiles of a normal strength reinforced concrete (RC) slab subjected to contact explosion are predicted and compared with the published experimental results. The hydrostatic pressure of the reservoir is modeled by using the specific internal energy method. The interaction between detonation products and dam-foundation-reservoir systems is also considered. The detonation products development processes, shock wave propagation, and failure modes of the dam subjected to underwater contact explosion with and without considering the hydrostatic pressure are compared. In order to analyze the underwater contact explosion effects on failure modes and dynamic responses of the dam, three positions of the detonation point, i.e., upper blast point, middle blast point, and lower blast point, are considered in this study. The results show that the initial hydrostatic pressure has a significant influence on failure characteristics of the dam subjected to underwater contact explosion. Underwater contact explosion detonated in the lower zone will cause more serious damage to the dam heel and threaten the overall stability of the dam. Hence, more attention should be paid to the deep water contact explosion.