Flume Test Study on the Breach Widening Process of Loess Landslide Dams under Different Upstream Water Inflow Flows
Due to the loess landslide dams are prone to erosion damage when encountering water,different income water flow rates have a great influence on the evolution mode of loess landslide dam failure,especially the form of dam fail-ure widening.In order to investigate the influence of different incoming water flow rates on the breach widening course of Loess landslide dams,a series of flume tests with different incoming water flow rates(0.6 L/s,0.8 L/s,1.0 L/s,1.2 L/s and 1.5 L/s)are set up,and the results are as follows:①Loess landslide dams breach widening under different incoming water flow rates is divided into two modes,transient course and complete course,when the incoming water flow rates Q≤1.0 L/s,the breach widening is a transient course,experiencing a process of breach penetration;when the incoming water flow rates Q>1.0 L/s,the breach widening is a complete course,experiencing three processes,such as the stage of breach penetration,the stage of rapid development,and the stage of stability;②The rapid development stage of breach widening is the main process in the complete course of breach widening mode,the erosion depth and slope angle control the stability of the soil body on both sides of the breach,the shape of the dam top breach and the changes in the flow rate of the breach reflect the change of the direction and strength of the erosion in the process;③The water sensitivity of the loess pro-motes the emergence of pipe surges to a certain extent,which makes the erosion inside the dam body more intense and leads to a transient course of breach widening;④The impact of downstream flooding varies between breach spreading modes,with floodwaters striking downstream quickly and strongly in the full-course mode,while the short-course mode requires a continuous and stable emergency response to deal with the flood risk.The study results could provide reference support for the failure mechanism and prevention measures of the loess landslide dams.
loess landslide damincome water flow ratebreach widening processerosion characteristicsflume test
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