Failure analysis of concrete gravity dam using coupled acoustic–structural analysis

The failure mechanism of a gravity dam under blast loading is much more complex than failure under other dynamic loads such as earthquakes. It is therefore important to evaluate the safety performance of these structures under blast load. The structural dynamic behaviour of Koyna dam, India, subjected to underwater explosion (UndEx) was investigated. The Johnson–Holmquist 2 model was used to capture the non-linear response of concrete. The dam–reservoir interaction was modelled using the coupled acoustic–structural technique, which employs a total wave formulation to incorporate the propagation of spherical shock waves. Dynamic responses such as displacement, damage profiles and principal stresses under various detonation depths, weights and reservoir levels were examined. The findings indicated that areas facing the explosion experience the most damage, while local damage occurred at the dam’s heel as the explosion depth increased. Additionally, displacement decreased notably as the TNT depth increased for a consistent explosive amount. The damage distribution in the dam was found to depend on both TNT depth and weight. Damage accumulation in the dam was substantially reduced by lowering the reservoir height (five different levels were assessed). The results provide valuable insights into the Koyna gravity dam’s response to UndEx under varying conditions.