高落差明渠截流方案优选实例试验研究

Optimized Scheme of Open Channel Closure with High Drop

针对某水电站工程明渠截流面临大水深、高流速、高落差、高单宽功率及合格截流材料难觅等带来的截流技术难题,通过水工模型试验,对不同戗堤和龙口形式进行了对比试验与结果分析,并提出了较为合理的戗堤轴线位置。研究表明:推荐方案充分利用了明渠导墙的导水作用,使水流在导墙的作用下形成"S"形流动,增加了水流流程,减小了龙口处的水力坡降;此外,流程形势由直到弯,水流紊动增强,流动阻力增加,动能耗散增加,从而改善了龙口处水流流态,降低了截流水力学指标和难度。研究成果为该工程的截流施工提供了数据支撑,可供类似工程设计参考。

Physical model tests were conducted to solve the technical problems of an open channel closure for a hy- dropower project with large water depth, high water velocity, high drop, high unit-wide power and qualified closure materials which are difficult to be obtained. Tests with different dikes and closure gaps were carried out and a prop- er location of dike axis was determined. Results show that the recommended closure layout increases the flow path, reduces the hydraulic gradient at the closure gap, and results in S-shaped flow pattern. Moreover, the S-shaped closure layout bends the flow path, and enhances the flow turbulence, increases flow resistance and kinetic energy dissipation, thereby improving the flow pattern at the closure gap and reducing the hydraulic difficulty. This re- search provides useful data for the closure construction and can be a reference for similar projects.