Experimental research on overflow cofferdam of Tankeng Hydropower Station in Zhejiang Province

The Tankeng Hydropower Station takes the single cofferdam with tunnel diversion as the diversion mode.Upstream and downstream cofferdams are overflow earth-rock cofferdam type.In order to further understand the flow conditions of various stages during construction diversion,ensure safety of cofferdam and dam during flood season,the overflow cofferdam diversion model experimental research has been conducted.Through the model test,the discharge capacity of diversion tunnel and the cofferdam have been tested;the flow velocities and flow patterns through the cofferdam,the dam and the diversion tunnel have been tested;the protecting measures of cofferdam and dam have been verified.According to the experimental rusults,further optimizing the structure of the cofferdam arrangement and the protective measures of upstream cofferdam have been made so as to provide guidance for construction deversion,river closure design and construction organization planning.