干清支浑型水库泥沙淤积形态和运动规律研究

Experimental Study on Sediment Transport Law and Deposition Feature of Hyperconcentrated Flood of the Tributaries Merging into Reservoir

支流含有大量泥沙的洪水从弯曲干流弯顶处汇入,是一种特殊的干支流交汇现象。当汇口处于电站水库内,将使其水沙运动规律更加复杂。通过模型试验对桐子林水电站上游近坝段的大量含沙洪水入汇过程进行模拟,研究了库区内泥沙淤积形态和粒径分布规律,结果显示:整体来看,库区河段仍将发生累积性淤积,河道逐渐向高滩深槽、顺直微弯方向发展;具体来看,干支流交汇引起的主流偏转与能量损失,形成了支流河口淤出拦门沙坝、主流区床沙粗化以及回流区大幅淤积这一复杂演变现象;从电站运行角度来看,前10年,推移质泥沙主要在支流淤积和输移,后10年内,推移质泥沙洲头逐渐推移至坝前,需要采取一定措施排沙,以保证电站安全高效运行。

The confluence of the hyperconcentrated flood of tributaries into the curved top of main river stream is a special phenomenon. When the confluence point is in the reservoir of a power station, it will make the water and sand movement law more complicated. Based on model test, the confluence process of the hyperconcentrated flood of tributaries into the reservoir of Tongzilin Hydropower Station is simulated. The result showed that:(a) as a whole, the cumulative deposition will still occur in reservoir, and the river channel will gradually develop to the trend of high beach, deep channel and straight slight bend;(b) in particular local area, the main stream deflection and energy loss caused by the confluence of trunk and tributary rivers result in the complex evolution of tributary estuary sandbar, bed sediment coarsening in main stream area and large-scale silting in backflow area;and (c) from the perspective of power station operation, the bed load sediment mainly deposits and transports in the tributaries in the first 10 years, and the bed load sandbank gradually moves to the front of dam in the second 10 years, so some measures should be taken to drain sediment to ensure the safe and efficient operation of power station.