<p>Persistently evolving global security challenges and increasing regional conflict risks have motivated growing research interest in the damage characteristics and failure mechanisms of concrete gravity dams subjected to underwater explosions. In this study, centrifuge tests on underwater explosions under 80 G were conducted, reproducing failure patterns consistent with the breach morphology of the Eder Dam. Based on the centrifuge tests, a fluid-structure interaction model for multiple media was established using the coupled Eulerian Lagrangian method, and a comparative analysis of the damage processes and failure mechanisms was conducted for the centrifuge tests, numerical simulations, and prototype dam. The effectiveness and reliability of centrifuge tests for structural damage modeling from underwater explosions were further validated. It is found that, during the near-field underwater explosions, the damage to concrete gravity dams is primarily governed by shock waves, whereas the bubble pulsation insignificantly affects the damage. As the structural strength of the dam increases, the dominant failure mechanism transitions from localized failure to global structural failure. In addition, horizontally arranged multiple detonations significantly expand the damage extent of the dam, and there exists an optimal burial depth and standoff distance that result in larger breaches for the same equivalent charge weight. The conclusions of this study provide valuable insights for blast-resistant safety design and risk assessment of dam structures.</p>