Study On Water Stop Failure Of Super High Face Rockfill Dam

Based on a super-high concrete faceted rockfill dam in the Yellow River Basin,this paper uses the finite element calculation method to study the problem of water failure.Firstly,the material partitioning,material calculation parameters,boundary conditions of the 3D model and the setting of the calculation condition of the project are briefly introduced.Then,a threedimensional seepage model is established to calculate the change of the seepage field of the dam after the failure of the water stop structure of the concrete face fill dam,and the changes of the seepage flow,hydraulic slope and seepage velocity of each material of the dam body with the fracture width and fracture elevation are analyzed when the water stop structure fails.The changes of hydraulic slope and seepage velocity with fracture width and elevation at the downstream escape point of concrete face rockfill dam were statistically analyzed to obtain the change of downstream escape point height with fracture width and fracture location,and the seepage safety was evaluated.According to the role of each material of the dam body after the failure of the water-stopping structure,specific engineering rationalization suggestions are proposed.Based on the actual situation,considering the silting effect of sediment on cracks in river water,the self-healing effect of cracks in panel rockfill dams was analyzed,and the silting effect of sediment on cracks in river water was simulated by changing the permeability coefficient of the fracture area.The calculation results of seepage flow,hydraulic slope drop and seepage velocity of each material before and after silting were compared and analyzed to quantitatively describe the self-healing effect of sediment on crack formation in river water.The main findings of this paper are as follows:(1)On the whole,the elevation change of the downstream escape point is not large,but the maximum value of hydraulic slope calculation of the downstream escape point is close to the slope value of pipe surge.With the increase of fracture width,the hydraulic slope drop value and increase of fracture width,the hydraulic slope drop value and escape point elevation of the downstream escape point will also increase to different degrees.(2)When the vertical joint,the peripheral joint single joint fails and all fails,the change of the wetting surface of the dam body is not obvious.When the permeability coefficient of the panel is increased by 10 times,the infiltration surface of the dam body changes greatly.It shows that compared with the change of the seepage field of the dam caused by the failure of the fracture water-stopping structure,the permeability coefficient of the panel has a greater influence on the seepage field of the dam.Therefore,when the dam body is poured for panels,it is necessary to reasonably arrange the phased and block construction of the panels according to various conditions such as flood degree and the force of the panels to ensure the construction quality of the panels and joints.(3)Vertical joint,after the water stop failure of the peripheral joint,the hydraulic slope of the cushion under the crack increases significantly,and the impact range is between 9 and 11 meters,and the increase is about 4 to 5 times the hydraulic slope drop value when it is not invalidated.With the increase of the width of the failure joint,the water-hydraulic slope of the water-stop structure and the transition material under the cushion,the reverse filter material and other materials have increased to varying degrees.However,according to the seepage calculation results,the change of each seepage element of each material under the crack is not a linear relationship with the increase of the crack width,but with the increase of the crack width,the change amplitude of the seepage element of each material under the crack is continuously reduced.(4)As the sediment in the river water remains in the cracks,the vertical joints and peripheral joints can play a good role in preventing seepage,reduce the head value acting on the bedding material,reduce the seepage flow,reduce the hydraulic slope drop value and seepage velocity value of the bedding material,overburden,etc.