泄水建筑物高含沙水流流量系数试验研究

The sediment transport feature of highly sandy water is fully utilized in the colmation by induced flood and high concentrated sand discharge in reservoirs. It also brings about some problems to the operation and management of water conservancy projects on sandy rivers. A noticeable problem is the high sediment's influence on the sand discharge and water drainage of pivots.The turbulent motion of sandy water is the central problem of sport dynamics of the sediment. At present, it is extremely intricate and complicated to analyze or work out numbers of the concrete conditions of the flow and sand. The water conservancy reckoners and design codes also have deficiency in the calculation formula of the discharge coefficient of sandy weir flows. The project chooses the representative no-ridge broadcrest weirs as the research object, observes the change law of every water conservancy factor, probes into different turbulent motions of the sandy water and clear water, explores the sandy water's influence on the discharge ability of outlet structures, making an analysis on the structure and motion mechanism of the highly sandy water and putting forward the calculation method of the drainage ability with different sediment concentrations. The central problem of sediment sport dynamics is the turblence structure of sandy water.The research findings are quite meaningful for the basic study of hydraulics and river regulation and construction, with academic meanings and practical values in the calculation formula enrichment of weir flows and the drainage ability confirmation of outlet structures.

高含沙水流的输沙特性，在引洪淤灌和水库高浓度排沙等方面都得到充分利用，但给多沙河流上水利工程运行与管理带来了一些问题，高含沙对枢纽排沙泄流能力影响就是十分突出的一个方面。挟沙水流紊动结构是泥沙运动力学的核心问题，目前通过建立运动方程，针对具体流动、含沙条件进行分析或数值计算异常艰深复杂，面向工程的水力计算手册及设计规范针对含沙水流堰流流量系数的计算公式存在缺失。本课题选择代表性无坎宽顶堰，通过试验观测水流中各项水力因子的变化规律，寻求含沙水流与清水紊动规律差异，研究含沙水流对泄水建筑物泄流能力影响，从高含沙水流结构和运动机理上进行分析，提出适用于不同含沙量范围的泄流能力计算方法。研究成果是水力学基础研究和江河治理建设的迫切需求，对丰富堰流计算公式和对泄流建筑物泄流能力的确定具有重要的学术意义和实用价值。

多沙河流上水工建筑物的泄流能力通常是根据水工手册或清水模型试验所确定的流量系数来计算，这种确定方法对少沙河流是适宜的，但对于含沙量较大的河流，泥沙引起浑水物理特性的变化对泄流能力的影响不可忽视。WES实用堰型应用广泛，本文选用新型三维电磁流速仪，对宽40cm，长30m的矩形水槽进行模型试验，采用粒径0.027mm的泥沙配备不同浓度浑水的过堰水力参数进行测定，结果表明：当含沙量低于100kg/m3时，综合流量系数与含沙量变化无明显相关联系，当含沙量介于100kg/m3至400kg/m3时，综合流量系数随含沙量增大而降低，当含沙量高于400kg/m3时，综合流量系数随含沙量增大而增大。在模型试验结果和天然河流资料的基础上，试验探明挟沙水流作用下堰流流量系数偏差的调整方式，通过量纲分析法和相关性分析，得出适用于不同含沙量作用下堰流流量计算公式。研究成果是水力学基础研究和江河治理建设的重要需求，对进一步完善堰流计算公式和对多沙河流泄水建筑物泄流能力的确定具有重要的学术意义和实用价值。