This study introduces a coupled peridynamics (PD) and smoothed particle hydrodynamics (SPH) model to handle the complex physical processes in concrete dam structures subjected to near-field underwater explosions. A robust coupling algorithm is applied to ensure accurate data exchange between PD and SPH domains, enabling the simulation of fluid-structure interactions. To account for the material behavior under high strain rates, a rate- dependent concrete model is integrated into the PD-SPH framework. The developed PD-SPH model is validated through simulations of centrifugal model tests, with results benchmarked against experimental findings and finite element method (FEM) predictions. The simulation captures key damage features, including horizontal tensile cracking at the dam head and an oblique penetrating crack in the dam body, forming an angle of approximately 17 degrees relative to the horizontal. Velocity and strain responses at critical monitoring points demonstrate strong agreement with FEM results, showcasing the model's capability in accurately predicting the structural responses and failure of concrete dams caused by underwater explosions. To the best of the authors' knowledge, research applying a coupled PD-SPH model to concrete structures under blast loading is still rare, particularly when considering the entire physical process, from explosive detonation to structural failure, accounting for fluid-structure interactions.

In order to explore the dynamic behavior and damage mode of shallow buried tunnel induced by underwater explosions (UWEPs), a fully coupled numerical model of a shallow buried tunnel based on Arbitrary Lagrangian and Eulerian (ALE) method was established. The strain rate effects of concrete and steel bar under explosion load, the explosion wave propagation, the interaction between fluids and solids, and the nonlinear response of the structure were considered. The reliability of the numerical method was verified by comparing the experimental and analytical results. The damage process and damage mechanism of submerged shallow buried tunnel due to UWEPs were investigated. The effects of saturated soil covering, explosive weight, buried depth and water depth on the dynamic behavior and damage mode of the tunnel were discussed. Finally, the dimensional analysis was used to obtain the functional relationship between the peak displacement, charge weight, buried depth and water depth. The results show that the saturated soil covering can effectively reduce the impact of explosion load on the tunnel. Increasing the buried depth can mitigate the blast effects on the structure, and the failure modes switch from local damage to global failure. The response of the tunnel increases with the increasing water depth, but the influence of water depth decreases gradually. The damage modes of shallow buried tunnel can be classified into local punching or spalling damage, global bending failure accompanied by spalling damage, and global bending failure.