Research On Energy Dissipation Mechanism And Fluctuating Pressure Of Special-Shaped Stilling Basin

For the high-head,large discharge projects,the application of traditional energy dissipaters by hydraulic jump put forward higher requirements of the anti-erosion ability due to high velocity and fluctuating pressure in the stilling basin.In recent years,stilling basin with drop sill by hydraulic jump as a new type of energy dissipater named a special-shaped stilling basin,which could reduce hydraulics indexes and sufficiently dissipate discharge energy changed by the stilling basin shape.The new stilling basin owned the combination advantages of trajectory and hydraulic jump,have a good development prospect and the research about the basin have important values of application in the projects.The fewer researchers focus on that.In this paper,based on two discharge structures with the basin,the hydraulic characteristics for protection structure of stilling basin were study by the combination of model test and numerical simulation.The main research contents are as follows:(1)Fluctuating pressure of slab in stilling basinThe experimental results gave decreasing rates of the fluctuating pressure compared by stilling basin with drop sill and sudden expansion and the traditional stilling basin,and present the drop height and sudden expansion rate at the smallest fluctuating pressure values.the shape of slab had been optimized.For high-low bucket stilling basin,the experiment and numerical simulation results present the mechanism of energy dissipation and characteristics and distribution of fluctuating pressure of slab were summarized.The optimal operation scheme was given at minimum floor fluctuating pressure.(2)The characteristics of fluctuating pressure at the dividing-wall of damBased on model test and numerical simulation,hydraulic indexes of fluctuating pressure were analyzed for drainage flood on the dividing-wall of the dam.Mechanism of influence of the downstream water level and the opening of the orifice on the maximum fluctuating pressure at the dividing-wall of dam was proved.A experience formula was defined for the position of the maximum fluctuating pressure at the wall.(3)The characteristics of fluctuating pressure on the guide wallThe characteristics of fluctuating load on the guide wall were study by hydraulic model test and reasons of the different fluctuating pressure distribution were analyzed between the guide wall of stilling basin with drop sill and the traditional stilling basin guide wall.The rules of fluctuating pressure have been summed up on the guide wall of stilling basin with drop sill.The results of the test and numerical calculation have been contrasted on the basis of hydroelastic model and dynamic response on the wall.(4)The relation between fluctuating pressure and the ground vibrationGround vibration carried out a preliminary study on the basis of Xiangjiaba dam fluctuating pressure test results and the numerical analysis.Energy rates of the fluctuating pressure to ground vibration under different operating conditions were calculated out.Combined with the fluctuating pressure distribution rules of each protective structure in the foregoing chapters,vibration suppression engineering measures are preliminarily put forward,which can provide help for the relative projects.