黄河下游透水丁坝瞬溃后水力及冲淤特性研究

溃坝是一种瞬时带有巨大破坏作用的灾害性过程，可引起河床的骤冲、骤淤以及下游岸滩失稳坍塌。基于MIKE21 FM软件构建二维水动力数值模型，模拟了黄河下游老君堂河段拟建透水丁坝群中首排丁坝瞬时全溃后所诱发的水流泥沙运动过程，分析了溃坝后床面剪切力的分布变化，阐明了坝群附近河床的冲淤特点。研究表明：首排坝瞬溃后，溃坝波受下游丁坝群的影响而改变了其传播演进过程线；溃坝对主槽的输沙能力影响较弱，但却显著地影响了坝区泥沙的起动和沉降；首排坝的坝体和次排坝的坝头是受损最严重的区域，因此建议采用实体丁坝与透水丁坝相结合的复合式配置方式，即首排坝和次排坝采用实体丁坝、其余位置采用透水丁坝，以加强各工况丁坝群运行的稳定性。

Hydraulic and alluvial characteristics of the lower Yellow River after the sudden dam-break of permeable spur dikes

Dam-break is a type of catastrophic process with instantaneous and huge destructive effects, which can cause sudden scouring and silting of the riverbed and even instability and collapse of the river bank in the downstream of the river. In this study, a two-dimensional numerical model based on the shape of the natural channel and the actual layout of the existing spur dike group was constructed using the MIKE21 FM software. The main objectives of this study are to simulate the downstream water and sediment transport process after the sudden failure of the first permeable spur dike, and then to analyze the changes in riverbed shear stress and the alluvial characteristics of the riverbed near the spur dikes. The results show that after the instantaneous failure of the first spur dike, the flood evolution is influenced by the downstream spur dikes and changes its process. However, the dam-break has little effect on the sediment transport capacity of the main channel, but significantly affects the incipient and settling motions of sediment in the area between the spur dikes. Furthermore, since the body of the first spur dike and the head of the second spur dike are the most vulnerable areas, a composite configuration structure of permeable and impermeable dikes is recommended for the spur dike group layout to improve its stability during operation, which is impermeable dikes for the first and second spur dikes and permeable dikes for the rest of the dike group.