Scale Model Test Study On Incipient Motion Of Tailing Dam Break Due To Overtopping

Tailings dam-break accidents usually pose serious threat to the people's lives and property safety of downstream residents and the surrounding environment.Uncertainty factors such as rainfall,flood,increase the probability of water level surging and overtopping in tailings reservoir.Therefore,it is necessary to investigate the dam breach pattern due to overtopping under extreme conditions.To analyze the tailings dam failure evolution pattern,a tailings dam overtopping evolution model was studied based on the physical model experiment method.We analyze the feasibility of incipient motion model test of tailings dam due to overtopping under normal gravity conditions.The main remarking conclusions are drawn as follows:(1)Based on the critical state concept,a theoretical model for the relationship between shear strength and void ratio of sandy soil was proposed.A series of oedometer tests and direct shear tests were carried out on copper and tungsten tailings with different particle sizes.The theoretical model enables the prediction of the shear strength of sandy soils with various void ratios and stress levels.(2)Incipient motion tests on sandy soil with various portion of coarse particle and dry density were carried out using a new self-developed incipient motion test device.According to the theory force balance of sediment particles under limit state,the relationship between sediment initiation and shear strength of soil was derived for predicting the incipient motion shear stress.The incipient motion shear stress obtained from experiment agree well with the perdition.(3)The overtopping scouring tests of homogeneous clay dams with different compacted density are carried out by using the starting flume device.The testing results reveal that compacted states has significant influence on the starting shear stress of clay dams.It is therefore feasible to control the incipient motion of model dams by controlling the compaction of clay,then further improving the analogous conditions in incipient motion of overtopping collapse of tailings dams in the scale model.