受支流入汇作用主河推移质运动演化特征试验研究

天然河流中存在着大量的主支交汇河流,在主支流相汇处,由于河相关系的变化,主支河流原有的水沙平衡状态被打破。通过一系列的水槽试验研究了交汇角为30°时支流来水、来沙对主流输沙特性的影响,获得了在支流有无来水、来沙时不同主支汇流比下的主河输沙率和累积输沙量随时间演化过程。试验表明:单一主河推移质呈“波”状输移,具有时空不连续性;支流仅来水时,由于无泥沙补给,交汇口及其下游会形成冲刷深槽,主流输沙率和输沙量强度在初始阶段很大,随着时间的推移,其值逐步衰减并趋于稳定;支流来水又来沙时,主河输沙特性与主支汇流比密切相关。

Experimental Study on Evolution Characteristics of Bedload Transport Motion in Main River with Tributary Action

The channel confluences are hackneyed,but the sediment transport motion at the confluence and main rivers considering the tributary effect isare very complicated.Based on flume experiments of the flow and sediment,the evolutionary process of bedload motion in main river with tributary action including three different cases has been discussed,namely without branch channel flow,branch channel flow only with clear water,branch channel flow with both water and sediment.The bedload transport rate and its accumulative sediment transport amount with the increase of time were recorded and analyzed for different discharge ratios q~* of the branch channel flow Q_b to combined tail-water flow Q_t in each case.The results demonstrated that the characteristics of bedload transport and local scoured bedform strongly depend on the flow and sediment conditions from tributary and the relationship between main and tributary rivers as far as hydraulic factors was concerned.