Numerical Simulation Study On Root Stones Loss In Dam Buttress Engineering

Root stones loss has always been a prominent engineering problems in the yellow river dam.It has a direct impact on the stability of the dam foundation and the overall safety of the project.So study on root stones loss under the impact of water flow is very important to the design of dam.The research of root stones loss involves fluid-structure interaction and sediment erosion.Based on the computational fluid dynamics software FLOW-3D,a numerical model which can be used to calculate root stones loss was established by using GMO model,sediment model and RNG turbulence model.Then the process of rolling loss of root stones and scour collapse were calculated and analyzed.In order to verify the correctness of the selected model,a model test of dam break water flow impact on fixed block in downstream and sediment scour by dam break water flow in flume were simulated,the result shows that calculated values of water flow and the sediment bed surface are in good agreement with the physical model test data.Then numerical test of the water flow acting on the cubic block was calculated,the output water flow force of numerical simulation was compared with the value of formula,and they are basically same.The verification result shows that the numerical model is accurate in the calculation of water flow,sediment transport and water flow force,it can be used to simulate the process of root stones loss.Based on the numerical model,the calculation of root stones rolling loss and scour collapse of an actual dam project were carried out and analyzed,the calculation result of root stones rolling loss shows that root stones and water flow affect each other in whole process.The most serious area of root stones loss around the dam buttress is the front head of dam,and followed by is upper cross corner area.Root stones of these two areas moved to downstream are mainly effected by water drag force and uplift force.Root stones in down cross corner are mainly affected by the water vortex force and numbers of lost root stones are less,part of root stones of connect dam section moved to upstream because of the water vortex force.The calculation result of scour collapse shows that the scour hole at the front head of dam buttress is the earliest and the deepest,the scour hole expand to upper cross corner and down cross corner by continuous scouring of water flow,and scour hole depth of the these two areas are similar.Sediment deposition in the dam crotch due to water flow vortex.The results of this study show that vulnerable parts around dam buttress are front head of the dam and upper cross corner,more attention of scour prevention should be paid on these two areas.