乌牛新闸下游冲刷模型试验及经验公式适用性

摘要

Elaborate on the downstream scouring problem, a physical model is established to observe the formation and development process of the scouring pit. Furthermore, the scouring pit location and depth variation with time is studied. Additionally, the results of physical model experiment and the empirical formula are compared and analyzed to explore the adaptability of the empirical formula in the plains of silt soil. The main conclusion of this work is that during low tide of the downstream, the lockage water forms drop flow in the scour stone cages causing significant erosion on the downstream. With the long-term erosion at the confluence of river terrain, the hydraulic jump near the confluence disappears gradually in the fixed bed physical model. With longer time, the scouring pit location shifts downward and the scouring pit depth increases from fast to a stable state. Moreover, in the plains of silt soil, the maximum scouring pit depth calculated from the Mao Chang-xu empirical formula of Nanjing Hydraulic Research Institute ( NHRI) is consistent with the results of the physical model experiment, which means that the formula can be applied in practice.%针对乌牛新闸闸下冲刷问题，建立水闸物理模型并观测闸下冲刷坑的形成及发展过程，研究冲刷坑位置及深度随时间的变化规律，并将试验成果与两种常用的冲刷公式计算结果进行对比分析，探索了冲刷公式在平原地区淤泥土质中的适用性。结果表明：当下游潮位较低时，过闸水流在防冲槽末端形成跌流，水流翻滚剧烈，对下游河道冲刷明显；随着汇合口河道地形的长期冲刷，汇合口附近的水跃逐渐消失；随着时间加长，冲刷坑位置整体有所下移，冲刷深度从快速增大逐渐趋于稳定；在平原地区淤泥土质中，毛昶熙公式计算的闸下最大冲刷深度与试验成果较为一致，具有较好的适用性。