Experimental Study On Seepage And Stability Of A Uranium Tailings Dam Under Strong Rainfall

In this paper,a uranium tailings dam in the south of China was taken as the research object,and three types of tail sand samples were taken at different positions and depths of the dry beach to analyze the relationship between the matrix suction and the moisture content and dry density,as well as the relationship between the permeability and inlet pressure and water content.A similar physical model(1:100)was established,and the displacements of the monitoring points of the uranium tailings dam and the saturation line of the uranium tailings over time under heavy rainfall(24-hour 500 mm and 800mm)were measured using a grating fiber system.The results showed:(1)There was no difference in the relationship between the suction and water content of tailings 1 and tailings 2.However,tailings 3 was contrary to the existing findings in the above rules and further research was needed.From the established SWCC and SSCC curves,when tailings 1 and 2 were used as the main dam material,the effect of matrix suction on the safety and stability of the uranium tailings dam is very limited.(2)The experimental results of saturation tailings permeability test showed that the permeability of the three kinds of uranium tailings shows different characteristics under different inlet pressures.It is difficult to find critical hydraulic pressures for tailings 1,while the critical hydraulic pressures for tailings 2 and tailings 3,especially tailings 3,are significant.The experimental results of the unsaturated tailings permeability test showed that the correlation between permeability and matrix suction is strong,and the fitting effect is good by empirical formula.(3)Under the 24-hour rainfall of 500 mm and 800 mm,the change of the saturation line of a certain uranium tailings dam was mainly in the middle and front of the dam relative to the initial saturation line.The vertical maximum displacement occurs in the middle of the dam;the lateral maximum displacement occurs in the front section of the dam.Through comparison with numerical simulations,it could be seen that the maximum and displacement of the saturation line under different rainfall conditions were basically consistent with the experimental values,indicating that the physical model experiment was effective and could reflect well the in-situ dam under two different rainfall conditions.The amount of displacement of each monitoring point.(4)Comparing the experimental results with relevant regulations,the safety coefficient(1.085 and 1.084)of this uranium tailings dam was lower than the procedure(1.15)under both rainfall conditions.It was recommended to strengthen the uranium tailings dam in the middle of the dam.Drainage measures to reduce excessively high saturation lines caused by heavy rainfall.