渗流边界上推移质输沙率

Bed load transport with bed seepage

天然河道边界上常由于地下水和地表水的水位不同而产生渗流,引起水流的非静水压力分布,进而影响推移质输移规律,也使得常用的推移质输沙率公式不再适用。利用水槽试验测定沙波的尺寸及运动速度与床面渗流水力梯度的关系,结果表明沙波的高度及运动速度随着向下渗流强度的加大而增加,随着向上渗流强度的加大而减少;进而结合理论分析,利用沙波运动特点估算推移质输沙率,并推导出推移质输沙率随床面渗流的引入而变化的计算公式,分析渗流引起非静水压力分布下推移质输沙率的变化。

The bed load transport rate in a river can be affected by the seepage-induced non-hydrostatic pressure distribution that is due to the difference in water level between the free surface in the river and the vicinal groundwater table.The objective of the study is to investigate the effect of seepage flows on bed load transport rates through laboratory flume experiments.The experiment focuses on the modification of dune geometry resulting from seepage flows and the celerity or the propagation of the sand dunes.The results show that the influence of flow suction on both dune celerity and height tends to be positive,while the opposite is true for the injection flow.By analysis of experimental flume data for sand dunes,qualifying the effect of seepage flows on bed load transport rates can be carried out.As the result,a modified formula for better estimating the average rate of bed load transport is proposed.