Numerical Simulation of Dam-Break Flood Routing and Sediment Erosion and Deposition Under Different Rainfall Conditions

Abstract

Landslide dam is a natural dam body formed by collapse, landslide and debris flow. The flood caused by dam break will cause significant risk to the downstream of the dam. Under the effect of rainfall environment, the erosion and deposition rate of flood and sediment in the downstream of the dam will be affected. This paper takes Tangjiashan dam as the research object, establishes the digital elevation model of the downstream channel according to the field survey and geological data, establishes the two-dimensional unsteady hydrodynamic model with the help of MIKE 21, explores the material movement law of the dam break flood in the downstream channel, and analyzes the influence of rainfall on the distribution of sediment deposition rate and sediment transport rate in the dam break flood The variation of riverbed thickness and the influence of flood sediment concentration rate. Based on the rainfall of dam break flood, this paper studies the sediment erosion and deposition law of dam break flood under different rainfall conditions. The results show that the occurrence of rainfall can significantly increase the sediment holding capacity of dam break flood. Under different rainfall intensities; The sediment deposition rate in floods will be affected by rainfall. The sediment deposition rate under the condition of rainfall is higher than that under the condition of no rainfall; Increasing rainfall intensity will increase the sedimentation thickness of the river bed near the collapse of the Tangjiashan dam, such as the collapse of the Shuimogou ditch. Based on the relevant research conclusions under different rainfall conditions, this paper could provide significant theoretical guidance for the flood erosion law of dam breaks and downstream rescue work.