中文摘要：

利用并重流排沙是控制水库泥沙淤积和避免水库浑水现象的一种有效手段，但是目前对水库水温分层环境下的情况却鲜有研究。基于自然水温分层的分层模型水库研究，分别在入流量为0．08～0．64m3／h、入流泥沙浓度为1．25～7．5g／L和泥沙粒径为0．01mm的条件下，进行了一系列分层水库异重流的中试研究，测定了水库中5个断面、6个运行时间下的垂向泥沙浓度分布，系统分析了其变化特性和影响因素。对于固定工况，定义出水口断面处泥沙浓度不低于10％最大浓度（≥10％Cmax）的位置为适宜排沙口位置。中试结果表明，在跃温层温度梯度为41～48℃／m的分层条件下，入流量和泥沙浓度均能影响水库内异重流的主要挟沙范围及适宜排沙1：7的位置。水库内最大泥沙浓度随入流量和泥沙浓度的增大而增大，其主要挟沙范围亦随之扩大，异重流排沙口的适宜垂向位置下移。

英文摘要：

Emission of sediments by density currents is one of the most effective measures for both controlling sedimentation and avoiding turbid water in reservoirs. However, little research has been repor- ted on thermal stratification in reservoirs. Under the boundary conditions of inflow rates of 0. 08 - 0. 64 m3/h, sediment concentrations of 1.25 -7.5 g/L and sediment size of 0. 01 mm, a series of pilot experi- ments were carried out to characterize density currents, using a naturally stratified reservoir model. Verti- cal distributions of sediment concentrations were measured at five cross-sections under six running times, and were systemically analyzed for variations and factors. For a given condition, a proper location of sedi- ment releasing outlet was selected where the sediment concentration was no less than 10% of the maxi- mum sediment concentration. The result showed that when temperature gradients in the thermocline were between 41 -48 ℃/m, both active sediment scour areas and proper locations of sediment releasing outlet were influenced by inflow rates and sediment concentrations. When the inflow rate and sediment concentration were increased, the zones for carrying sediment outlet would decrease. maximum sediment concentration in would expand, and the depths of the the reservoir would increase, the main reasonable location of sediment releasing