Numerical simulation of failure modes of concrete gravity dams subjected to underwater explosion

• The effects of mesh size about underwater explosive are studied.
• Failure modes of gravity dams subjected to underwater explosive are discussed.
• The antiknock performance of gravity dams under blast load is investigated.
• Lowering the water level before foreseeable war is an effective defense measure.

The failure modes of concrete gravity dams under blast loading are the key problems to evaluate the antiknock safety of the dam. Dynamic failure process of structures under blast loading is much more complicated than that under other loadings such as static and earthquake loadings. Many researchers have conducted comprehensive experimental and numerical investigations of civil structures’ response to blast loading. However, corresponding studies of concrete gravity dams are limited. This paper performs numerical simulation of antiknock performance and failure modes of concrete gravity dams under blast loading. Firstly, the pressure and impulse produced by underwater explosion are calculated. The numerical results are verified by comparing with analytical expressions in different scaled distances. By analyzing the effects of mesh size, some interesting conclusions regarding the mesh size for actual events are obtained. Subsequently, the possible failure modes of concrete gravity dams subjected to underwater explosion are discussed. Strain rate effect of concrete materials is also taken into consideration in establishing the fully coupled model of the gravity dam. The dynamic response of the dam subjected to underwater explosion is performed for different dam heights, varying from 30 to 142 m. The influence of the dam height, standoff distance and the upstream water level on the antiknock performance of the dam is also investigated.