Ezperimental Research on the Design of Overtopped Cofferdam and Surface Protection of Tankeng CFRD During Flood Season
The Tankeng hydropower station locates in the middle reach of Xiaoxi River in Qingtian County of Zhejiang Province.It is a key power station of Oujiang River basin hydroelectric cascade development. The total installed capacity is 600 MW. The dam is concrete faced rockfill dam (CFRD) with crest elevation of 171.0 m and the maximum height of 162.0 m. Overtopped cofferdam and a diversion tunnel are used to diacharge in flood season during construction period. The diversion tunnel with the dimension of 12m×14m locates on left bank near the dam and has a length of 1,070.0 m. The cofferdam can resist flood with return period of 10 years during dry season (October to April of next year) and the corresponding design discharge is 2,420 m3/s. The overtopping flood has return period of 20 years during flood season and the corresponding design discharge is 10,400 m3/s.Upstream and downstream cofferdams are overtopped cofferdams.In initial design,crest elevation of upstream cofferdam is 56.8 m and crest elevation of downstream cofferdam is 38.1 m.In the preliminary model experiment,the discharge capacity of diversion tunnel and the cofferdam have been studied,the flow velocity and flow regime through the cofferdam and the dam have been tested. The protective measures of cofferdam have been adjusted according to the model experiment results. The concrete slab made up of blocks with size of 10m×10m×0.8m has been changed to the whole concrete slab,longitudinal joints along the direction of flow were set at intervals of 12 m,Drainage holes at the downstream side of the slab were set between the El.37.5 m and El.34 m. To ensure the safety of cofferdam and dam in the flood season,the weir-type modification model experiment is conducted.By combination of different schemes through reducing the crest elevation of the upstream cofferdam,raising the platform elevation of upstream cofferdam,raising the overtopping elevation of the dam,as well as raising the crest elevation of the downstream cofferdam,the structure of the upstream cofferdam and downstream cofferdam,placement elevation of the dam have been optimized. The technical measures to improve the upstream cofferdam hydraulic conditions and protect dam surface during flood season have aslo been studied. According to the model experiment results,combining with the distribution of dam placement materials,construction schedule and the experience of similar projects,the different protective measures are adopted in different parts of the dam surface.Research results provide important reference for the design of diversion and closure,construction organizing and dam construction during flood season.
Tankeng CFRD Overtopped cofferdam Construction during flood season Model ezperiment
Yang Lei Hu Zhigen Xiao Huanxiong
Wuhan University,Wuhan 430072,China
国际会议
The 1st International Symposium on Rockfill Dams(第一届堆石坝国际研讨会)
成都
英文
517-523
2009-10-18（万方平台首次上网日期，不代表论文的发表时间）