三峡水库泥沙絮凝机理解析(摘要)
王党伟，吉祖稳，胡海华，董占地
(中国水利水电科学研究院流域水循环模拟与调控国家重点实验室，北京 100048)
【摘 要】 天然水体泥沙絮凝的作用力主要来源于颗粒表面的电荷作用，其絮凝的基本原理可以用DLVO理论解析。以三峡水库中的水体环境因素为基础，通过DLVO理论量化了颗粒之间的作用能和作用力。通过对颗粒之间位能曲线上特征值与泥沙颗粒相对运动具有的动能之间的对比，得到了泥沙颗粒能够形成絮凝的水动力条件。对比三峡水库具体的水动力因素发现，坝前水深较大，当泥沙处于水体的中层时更容易产生絮凝；水库中泥沙的絮凝体均较为疏松，颗粒之间相互作用力较小，容易在水流中被剪切破坏。最后通过力的平衡关系得到了絮凝体的极限下沉速度，沉速等于絮凝体极限下沉速度的单颗粒泥沙粒径即为絮凝临界粒径，约为0.019mm，小于临界粒径的单颗粒泥沙的沉速需要考虑絮凝因素而进行修正。
【关键词】 泥沙絮凝；三峡水库；絮团沉速；絮凝临界粒径
基金项目：中国水科院“十三五”基础理论研究项目(SE0145B362016)；流域水循环模拟与调控国家重点实验室自由探索课题(2016TS07)；水利部科技示范项目(SF-201610)。
作者简介：王党伟(1982— )，男，陕西乾县人，博士，主要从事水沙运动基本理论及数值模拟研究。
E-mail:wangdw17@126.com
Theory Analysis of Sediment Flocculating in Three Gorges Reservoir
WANG Dangwei,JI Zuwen,HU Haihua,DONG Zhandi
(State Key Laboratory of Simulation and Regulation of River Basin Water Cycle,China Institute of Water Resources and Hydropower Research,Beijing 100048)
Abstract:Sediment flocculating in water is mainly caused by charges on particles’ surface and the principle of the flocculation can be explained by DLVO theory.According to water environmental factors in Three Gorges reservoir,potential energy and forces between particles are evaluated based on DLVO theory.The critical water dynamics conditions were obtained by comparing extremum in synthetic potential curve and kinetic energy caused by relative velocity between particles.It is found that sediment flocculating is apt to happen when water level is high or in the middle to lower level of the water according to flow dynamics in Three Gorges reservoir.The flocculation is relatively loose and which is prone to be broken because attraction between particles is small.So the settling velocity of the flocculation is limited and the critical diameter of sediment under which the sediment need to be considered affected by flocculating is 0.019mm,so the settling velocity should be revised according to the limited settling velocity of flocculation when sediments are smaller than this critical diameter.
Key words:Sediment Flocculation;Three Gorges Reservoir;Settling Velocity of Flocculation;Critical Diameter of Flocculating