Effect of the close-in underwater explosion pressure distribution on the concrete gravity dam

The purpose of this study is to investigate the impact of explosions on the nonlinear dynamic responses of concrete gravity dams (CGDs) by employing the equation of state for material behavior, which provides a hydrodynamic material model. Multiple strength models have been utilized to simulate explosions precisely. These models include the Riedel–Hiermaier–Thoma model with strain rate effects, the Johnson–Holmquist model, the Jones–Wilkins–Lee model, and the Polynomial model. These models are used to accurately describe the behavior of concrete, foundation, explosive, and water materials, respectively. For the exact numerical simulation of explosions, a finite element model is developed and the finite element method (FEM) is used for analysis. The FEM results are used to adjust the coefficient of Cole’s empirical equation for the phenomenon of underwater explosions (UNDEX). Following that, a simplified equation is presented to determine the maximum pressure in the CGD as a result of UNDEX conditions. Furthermore, this study compares the effects of close-in explosions in the cases of empty and full reservoirs to assess fracture mechanisms. The results of this study indicate that the pressure intensity in a CGD is greater when the reservoir is full than when it is empty. The intensity of the pressure caused significant damage during UNDEX, namely, in the top section and the neck of the dam. In addition, this phenomenon causes widespread fractures on the exterior surface of the dam structure. Additionally, the maximum distributed pressure along the assumed line on the neck during UNDEX is nearly seven times greater than that resulting from an air explosion. In summary, UNDEX causes significant damage and poses a threat to the overall integrity of the dams.