Structure Design Research of Sand-guide Sill in Tailrace Tunnel Outlet of Diversion-type Hydropower Station and Its Application

In order to meet the requirements on site construction conditions and construction period, a new sand-guide sill structure in tailrace outlet, that is transformed from cofferdam, is used in Jinping II Hydropower Station. The research shows that the new structure is reasonable, and has little effect on tail water discharge flow and power generation efficiency. The new sand-guide sill structure can reduce construction difficulty, improve maintenance condition, shorten construction period and achieve design goals. The practice provides a reference for the construction of tailrace project in similar diversion-type power stations.