Coupling effect analysis of dam break flood spread and building collapse based on numerical simulation

Large-scale floods induced by dam failures could cause significant structural damage to buildings and massive loss of life. The coupling effect of large-scale flood spread and building collapse has complex impacts on the entire flow field, affecting flood risk assessment and building vulnerability evaluation. In this paper, a dynamic elevation change model designed to seamlessly interface with a structural vulnerability assessment model to investigate the interaction effect between floods and buildings is presented. The efficiency of the framework was validated by reconstructing the Gleno Dam-Break flood in Italy. Subsequently, a hydrodynamic model of the Jinsha-Yalong River that considers dynamic building collapse was established. The proposed model was compared with two traditional building treatment approaches and one that ignored the buildings. The results show that the interaction between the flood and buildings decreases the low-velocity area (below 1 m/s) by 7.44%-9.56% while increasing the high velocity area (above 4 m/s) by 10.71%-11.96%. Traditional and neglecting building treatments provide preliminary insights into densely built areas, and the latter could be an alternative for simplification because it can represent the worst-case scenario. Building collapse in response to large-scale floods typically occurs in four stages: flood spread, rapid expansion, gradual expansion, and flood recession. This analysis offers novel perspectives on flood prediction and simulations where the floodplain may contain buildings. This method could be useful for assessing structural vulnerability associated with large building stocks and developing flood mitigation strategies in densely populated areas.