山区河流河床形态对推移质输沙率影响的试验研究

Experimental study on the impact of bed forms on bed load transport in mountain streams

  • 摘要: 为探索山区卵砾石河流推移质运动受水流条件和河床形态的影响规律,开展了大比降浅水流动条件下卵砾石输移的室内水槽试验,获得了两组泥沙组成的19个流量条件下的水流、泥沙及河床三维地形场数据。结合室内水槽试验及文献中的天然河流输沙观测数据,分析了不同水沙输移阶段水流阻力、河床形态与推移质运动之间的关系。试验结果表明:河床阻力系数随着河床形态强度参数增大而增大,形态阻力与河床形态强度参数相关性更强。在泥沙补给充分阶段,推移质输沙率与床面阻力、形态阻力及河床形态强度参数均呈正相关关系;在泥沙补给不充分的水流冲刷阶段,推移质输沙率随河床形态强度参数增大而减小。

     

    Abstract: The flume experiments of bed load transport in the conditions of highslope shallow water flow were carried out in order to explore the impact of flow hydraulics and bed forms on bed load transport in gravel-cobble rivers in mountainous areas. A total of 19 runs were conducted with two groups of sediment mixtures. A data set of fluid hydraulics, sediment and 3D topographic field of riverbed in each run were obtained. The analysis of interrelationships among the flow resistance, bed form and bed load transport in different flow and sediment transport stages was made, by combining the flume experimental data and the observed data from natural rivers in the references. Experimental results demonstrate that the riverbed resistance coefficient increases with the increase of riverbed morphological strength parameter. The form drag is strongly correlated with riverbed morphological strength parameter. In the stage of sufficient sediment replenishment, the bed load transport rate is positively correlated with skin friction, form drag, and riverbed morphological strength parameter; in the current scour stage where sediment replenishment is insufficient, the bed load transport rate decreases with the increase of riverbed morphological strength parameter.

     

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