三峡水库变动回水区河道推移质输移特性研究

Study on Bed Load in the Backwater Change-area of Three Gorges Reservoir

通过与三峡库区有关的野外实测资料、模型试验和计算资料,分析了三峡水库变动回水区河道推移质输沙特性.三峡水库运行末期,变动回水区泥沙淤积物以沙质推移质为主,其中上段还有卵石推移质.从上游往下游,泥沙淤积物的颗粒逐渐变细,主槽的粒径组成较粗,而边滩的粒径组成较细.随着水库运行年限的增长,主槽泥沙颗粒经历着粗化过程,而边滩却处于不断细化过程.主槽中原来淤积的细颗粒泥沙由于新淤积粗颗粒的保护和荫蔽作用,主槽的泥沙尽管粗化,水库运用后期的主槽淤积物仍有较细的泥沙颗粒存在.对于物模试验中放水过程对推移质输沙的影响、水库变动回水区所特有的碍航现象,以及修建向家坝和溪洛渡水利枢纽后变动回水区的推移质泥沙输移等问题,还有待在相关性基础理论中进一步研究.

Based on the data of field survey,physical model and mathematic model,this paper studies the transportation law of bed load in the fluctuating backwater area of the Three Gorges Reservoir.Sandy bed load is the chief part of the deposited sediment with a little pebble bed-load.The size of the deposited sediment is smaller and smaller from the upper reaches to the lower reaches.And the size in the main channel is bigger than that in the marginal bank.With running time increasing,the size of the deposited sediment in the main channel is bigger and bigger,however,smaller and smaller in the marginal bank.Despite the deposited sediment is coarse in the main channel,the small sediment still exists due to the protection and shield of the coarse sediment.Moreover,some interesting and important questions needing to be further studied are also proposed,such as the water-sand series of physical model,special conditions of obstruction to navigation and the bed load transportation after construction of the Xiangjiaba and Xiluodu Reservoirs.