Study On Energy Dissipation And Seepage Flow Analysis Of Jinshaxia Hydroelectric Station

Jinshaxia hydroelectric station is a low dam stream-flow conduit type hydroelectric station with a total capacity of 70MW and average year power generation of 26530 ten thousand KW.h. The hydroelectric station opened in 2004 February, and will be finished at the end of 2005. Height of flushing sluice of the hydroproject is 29.2m. The hydroproject is on the basis consist of stone, gravel and sand, and energy is dissipated mainly by the stilling basin, and seepage defend is designed using level blanket. The scheme of energy dissipation and seepage flow analysis are studied in the paper.The problem of energy dissipation should be considered from the whole scheme. The whole scheme arrange of the energy dissipation defended to scour adopts the following performance: (1) Lower the sluice height; (2) Sluice chamber to stilling basin diffusion slope; (3) 0.5m high baffle sill at the slope end of the bottom of stilling basin; (4) In the stilling basin end upstream 10 m left-side wall direct major river bed buckling 10? (5) At the stilling basin end connect 35m apron to readjustment flow; (6) At the apron end establish 7.2 m deep key-wall to defend to scour, key-wall downstream filled the reinforcing cage rubble, strong the stream bed. The scheme of above sluice vital dissipation of enery is through the intact hydraulic model experiment verificate. Escape 30-years frequency flood, at the apron end average velocity is 3.6m/s, stream bed filled rubblemaximum scour depth 1.0m.Escape 500-years frequency flood, apron end average velocity is 4.37m/s, stream bed filled rubble maximum scour depth 2.8m.It is even to open the discharge orifice, and make the even distribution of outlet flow on the downstream major river bed, combinely on the downstream stream bed fill the reinforcing cage rubble, can validate to lower the downstream stream bed average velocity and maximum scour depth, to satisfy the diversion vital request of the dissipation of energy, defend to scour. The sluice vital dissipation of energy simplified the scheme arrange, economize the investment, accumulate some experience at dissipation of energy work developments of the high sluice on gravel foundation.The diversion vital seepage flow analysis use the straight line proportion method, the improvement resistance method and the numerical simulation method. The straight line proportion method compute the flood scouring sluice on normal work seepage flow decline J=0.157, improvement resistance method compute the flood scouring sluice on normal work seepage flow decline J=0.167, and satisfy sluice foundation stability request. The numeric calculation method compute sluice and dam foundation seepage flow level decline J=0.1~ 0.135, smaller than the straight line proportion method and the improvement resistance method's result, the numeric calculation method also give the result of seepage flow vertical decline J=0.28~0.8.The sluice dam foundation seepage flow compute result, normal work of each sluice (dam) the level decline satisfy the sluice dam foundation stability request, the seepage vertical decline slightly over maximum admission, the sluice dam foundation pressure distribute normally. The accuracy and simplicity degree of each computation method is different, finally result should be mainly with the improvement resistance method that the accuracy and simplicity degree in center and engineering practice than others.