Research On Correlation Of Macro And Micro Parameters Of Reinforced Tailings Interface And Stability Of Tailings Dam

Tailings sand is the granular bulk waste left behind after the development of mineral resources.It is usually piled up by the way of setting up tailings pond.The safety and stability of the slope of tailings dam is an important problem,which is related to the safety of life and property of the downstream residents.However,there are few natural tailings pond resources in the face of the shortage of land resources.It is of great practical significance to study the safety and stability of tailings pond by increasing slope ratio by reinforcement.(1)The mechanical properties of the interface between tailing sand and geogrid are studied by the direct shear test in the laboratory.The macro mechanical parameters of several important factors are obtained.The macroscopic analysis shows that when the volume is certain,the moisture content is negatively related to the density,the water content is positively correlated with the apparent cohesion.With the increasing of water content,the friction angle of the interface increases first and then decreases.(2)Through the analysis of interface characteristics between tailing sand and geogrid and curve fitting of test data,the relationship between initial shear stiffness and water content and overlying load of tailing sand is studied.The friction coefficient of each group of direct shear test interface is obtained.The comparison error between the peak shear stress obtained by the new shear model and the actual peak shear stress is relatively small,The average initial shear stiffness of four water content without reinforcement is compared with that of the four water content under the condition of reinforcement.The strength change law of shear strain band after reinforcement is analyzed.(3)The two-dimensional shear test model was established by PFC discrete element to simulate the indoor direct shear test,and the meso mechanical parameters were obtained.Through the analysis of the correlation of macro and micro parameters,the shear test model established by PFC software was inverted continuously,and finally the curve similar to the actual test results was obtained.The apparent cohesion increased gradually and the normal stiffness value decreased slightly,The density and friction angle of tailings sand and normal stiffness also increase gradually.According to the macro mechanical parameters of each group of tests,the normal stiffness k_nand tangential stiffness k_sof the fine mechanical parameters can be obtained.(4)The macro mechanical parameters were obtained by the direct shear test in the laboratory.The shear test model was established and the micro mechanical parameters were obtained by using PFC discrete element software.The large displacement change area was determined by using the shear model cloud chart,and the influence law of shear strain zone between Geogrid and tailing interface was studied by combining with the non-point measurement and analysis,The influence distance of shear strain zone on the interface of reinforced tailings is discussed.(5)After the numerical simulation and optimization of the tailings,the optimization scheme of the tailings slope is determined.The safety coefficient of the tailings dam can be greatly improved by reinforcement,and the anti slip stability of the tailings dam can be increased.However,with the gradual increase of the slope ratio,the safety factor will decrease,The slope ratio of reinforced tailings dam is calculated by Bishop method and Janbu method when the safety coefficient of reinforced tailings dam is the same as that of the actual project,which provides reference for the engineering application of reinforced tailings dam.This paper has 38 pictures,15 tables and 79 references.