Study On Distribution Law Of Saturation Line In Relatively Stable Seepage Field Of Dry Stack Tailings Pond Under Multi-year Rainfall

At present,the tailings pond storage method is still dominated by traditional wet storage.However,the wet tailings pond is prone to dam break due to the characteristics of flow tailings and unstable dam.In order to improve the stability of tailings pond and reduce environmental pollution,tailings dry stacking technology has become a development trend for tailings storage.Dry stacking tailings pond has become a new trend of tailings storage because of its significant safety and environmental protection advantages.However,there is no perfect calculation method for the seepage field in the dam body in the current design of dry stack tailings pond.Under the cumulative influence of long-term periodic rainfall,the research on the evolution law and final distribution pattern of seepage field in dam body is not mature,which leads to the unreasonable design of seepage drainage facilities and dam slope of dry stack tailings pond,and limits the popularization and application of dry stack tailings pond.In this thesis,a numerical calculation model of dry stack tailings pond with years of cumulative rainfall infiltration is established.The key factors affecting the evolution of seepage field in dry stack tailings pond under long-term rainfall are determined.From the evolution process of pore pressure and saturation line in the dam with time,the final form of seepage field evolution of dry stack tailings pond under long-term rainfall infiltration is found,which is proposed and named as relatively stable seepage field,and the factors affecting the relatively stable seepage field are analyzed.On this basis,the energy equation and Darcy ’s law were used to established the differential equation of the saturation line of the relatively stable seepage field.Combined with the boundary conditions of rainfall infiltration and the downstream boundary conditions of the tailings pond,the differential equation of the saturation line is solved,and the analytical solution of the saturation line of the dry stack tailings pond is established.The analytical solution and numerical simulation results of the saturation line under various working conditions are compared to verify the correctness of the analytical solution.Due to the complexity of the function form of the analytical solution of the saturation line in practical engineering applications,the method of introducing the function rotation matrix is adopted to obtain the simplified solution of the saturation line analytical solution of the dry stack tailings pond.The applicability of the simplified solution is verified by the comparison between the simplified solution and the analytical solution and the numerical simulation solution.Based on the results of the analytical solution and the simplified solution,the parameter sensitivity analysis is carried out,and the main factors affecting the minimum depth and height of the saturation line are obtained.The results of this thesis indicate that the shape of the relatively stable seepage field formed by the dry stack tailings pond under the action of perennial periodic rainfall is mainly affected annual by rainfall,rainfall infiltration area and the slope of the bottom slope of the tailings pond.The seepage field can be used as the basis for the design of the seepage drainage facilities and dam slope of the dry stack tailings pond,and can be used to predict the saturation line of dry stack tailings pond.