Hydro-mechanical SPH-DEM framework for blast-induced damage evolution in concrete gravity dams

Blast loading can induce rapid crack propagation and severe damage in concrete gravity dams, particularly under the combined influence of reservoir loading and material heterogeneity. This study develops a hydro-mechanical SPH–DEM framework to simulate blast-induced damage evolution in concrete gravity dams. Intact concrete is represented by SPH particles, which are converted into DEM particles after failure to capture the transition from continuum deformation to crack opening, coalescence, and post-failure interaction. Spatial variability in concrete properties is further introduced to account for material uncertainty. The model is validated through benchmark fracture and blast tests and subsequently applied to HW Dam to investigate the effects of blast intensity, location, reservoir loading, and material heterogeneity. Results show that blast loading initially generates localised compression–shear damage, followed by tensile crack propagation driven by stress-wave reflection and crack-tip concentration. Reservoir loading accelerates damage growth by modifying the initial stress field, whereas blast location and material heterogeneity govern crack penetration and damage distribution. The proposed framework provides an effective approach for analysing blast-induced damage and fracture processes in concrete gravity dams under coupled hydro-mechanical conditions.