西藏扎拉水电站水库泥沙对电站运行影响试验研究

为了分析西藏玉曲河扎拉水电站运行后水库泥沙对电站取水发电产生的影响,基于扎拉电站整体河工模型试验成果,对扎拉电站运用50 a水库泥沙淤积过程,泄水建筑物及电站引水口前泥沙淤积分布、淤积高程,电站过机泥沙特性进行了试验研究。结果表明:水库运用50 a末,库区泥沙基本达到冲淤平衡,水库淤积总量约占总库容的66.45%;坝前泥沙淤积高程基本与底孔进口底高程齐平,对底孔泄流排沙影响不大;电站引水口前形成较明显的冲刷漏斗,引水渠淤积对电站正常引水影响不明显;电站过机泥沙,在水库运用初期没有0.1 mm的粗沙,在水库运用50 a末,遇常年含沙量洪水,过机泥沙中粒径0.1 mm的粗沙占过机总沙量的3.2%。建议下阶段进行优化水库调度,提高水库排沙效率的研究,进一步减少水库泥沙淤积,减轻泥沙对机组的磨损。

Influence of Reservoir Sedimentation on Operation of Tibet's Zhala Hydropower Station

In order to investigate the influence of reservoir sedimentation on the operation of Zhala hydropower station on Yuqu River of Tibet,we conducted overall physical river model test and researched the sediment accumulation process in an operation period of 50 years,the distribution and elevation of sediment deposition in front of discharge structures and water inlet of the power station,as well as the sediment characteristics through turbines.Research results suggest that in the end of the 50-year operation,the sediment of the reservoir area basically reaches scouting-deposition balance,with total deposition quantity reaching about 66.45％of the reservoir capacity.The sedimentation elevation in front of the dam is almost equal to the elevation of water inlet bottom of bottom hole,posing little impact on sediment discharge through bottom hole.Moreover,apparent scouring funnel is formed in front of the power station inlet,indicating that sediment accumulation in approach channel has no obvious influence on water diversion of the power station.In initial impoundment period,the particle size of sediment through turbine is less than or equal to 0.1 mm,but in the end of the 50-year operation,coarse sediment (particle size larger than 0.1 mm) accounts for 3.2％ of the total sediment through turbine.In the aim of reducing sedimentation and abrasion to the power units,we recommend to optimize the reservoir scheduling and to improve the sediment discharge efficiency in the next stage.