偏桥水电站首部枢纽设计

Design of head structure for Pianqiao hydropower station

偏桥水电站是一座长引水式中高水头电站,对所引水含沙量粒径的控制相对较严格。电站首部枢纽,受地形地质及移民因素限制,只能修建低拦河闸坝,较小的库容形不成以库代池的取水方式,为避免修建大规模沉沙池,节约工程投资,在地形条件许可的情况下,直接引用上游沙坪水电站尾水,形成首尾结合的串联取水方式,达到"清水"不下河的目的;另外,通过修建闸坝获取河道区间来水,经小规模的沉沙池沉沙,输水到既是沙坪水电站的尾水池,又是偏桥水电站调压前池的输水明渠,其宽浅式的结构避免了上下游2座水电站尾水、进水水位的频繁波动,又使偏桥水电站引水方便、稳定。通过水力学模型试验和实际运行验证,达到了预期的效果。

Pianqiao hydropower station is a middle-high head station with long headrace structure, which puts strict requirement for controlling the particle size of sediment in diverted water. Due to restrictions from geological and topographical conditions as well as resettlement issues, only a low dam barrage can be built for the head structure of the station Therefore , the small reservoir capacity could not supply water instead of pond. In order to avoid building a large stilling basin and save project investment, water is directly taken from the tailwater of Shaping hydropower station at upstream under allowable geological conditions, which forms a series water-take mode without ＂clear water＂ discharged into the river. In addition, through construction of the dam barrage for diverting the intervening inflow via a small stilling basin into the tailwater pond of Shaping station, which also services as the surge forebay of the wide and shallow open channel of Pianqiao station, frequent fluctuation of tailwater and intake level for the 2 hydropower stations was avoided, providing convenient and stable water diversion for Pianqiao hydropower station. The hydraulic model tests and actual operation proved the expected results of the structure.