The Stability Analysis Of Ternary Hole Tailings Dam Based On Seepage And Stress Coupled-Strength Reduction Method

With the rapid development of modern industry, the demand for mineral resources is Constantly increasing. meanwhile, the mined ore of mine would be discarded after selection of Useful ingredients,the solid waste also increased dramatically, so that the tailings by exposed in nature accounted for a considerable land area, the height of the tailings dam also increased accordingly. Because the tailings dam in the natural environment will exist for a long time, if tailings dam is destroyed by other outside powers, it would produce very enormous threat to the surrounding environment、production and living of downstream residents and mine production facilities. at the same time, it also caused incalculable economic loss to the country. groundwater can affect the stability of tailings dam,a large number of tailings dam accidents are caused by the effect of groundwater. In fact, as long as there is the presence of water, stress field and seepage field can influence and interaction each other, so that they are in a complex dynamic process,constituting the relationship of fluid-solid coupling. Studing the effect of groundwater seepage to tailings dam stability has great practical significance. This thesis takes the ternary hole tailings dam as the research object basing on the theory of fluid-soil coupling and the finite element strength reduction method, we use large-scale finite elementsoftware ABAQUS analysis the stability of ternary hole tailings dam by two-dimensional numerical simulation. In this paper, the main research contents and results are listed as follows:(1) The thesis introduces several important and commonly used method of analysising tailings dam or other natural slope. It also elaborate detailedly the basic principle of finite element strength reduction method and the advantage of the stability of analysising tailings dam, instability criterion of the finite element strength reduction method is analysised and researched by concrete example of a uranium tailings.(2) In accordance with darcy’s law and other related the theory of seepage calculation, the stable seepage and unstable seepage differential equation would be deduced by the fluid continuity equation. This paper expounds the interaction of the seepage field and stress field and mechanism of seepage/stress interaction, it is concluded that the mathematical model of seepage field and stress field influence each other.The mathematical model of the seepage and stress coupled would be formed through combining the two mathematical model, this article also discuss how to analysis stability of tailings dam using strength reduction method in fluid-soil module of ABAQUS program.(3) Based on finite element strength subtraction, safety coefficient are calculated respectively under different parameter combinations of tailings dam, while material parameters not only include the cohesive force, internal friction angle, elastic modulus and poisson’s ratio, but also include bulk weight of geotechnical materials and dilatancy angle, etc.The results show that the cohesive force, internal friction angle affect largerly on the safety coefficient of tailings dam, while safety factor and the cohesive force, internal friction angle is almost a linear relationship.the elastic modulus and poisson’s ratio does not affect the safety factor. It is concluded that the influence of bulk weight on the stability of tailingsdam is uncertain and ignoring dilatancy angle will make the results of calculation are generally more conservative.(4) This thesis takes the ternary hole tailings dam as the research object and a two-dimensional model is established, using the finite element strength reduction method calculate and analysis the stability of dam slope in three kinds of working conditions of anhydrous dry, seepage and stress not coupled, seepage and stress coupled. Safety coefficient of dam slope was respectively 1.6, 1.42 and 1.6 under three different conditions. The effect of sweep and stress coupled is obvious to the stability of tailings dam from the calculation results. Therefore, in the analysis of groundwater seepage problem on the stability of tailings dam,considering coupe of sweep and stress is very necessary, also provide reference for similar engineering analysis.(5) The errors of safety factor calculated by using the finite element strength reduction and limit equilibrium method are respectively 4.37%and 4.9%. obviously, the displacement mutation of each feature point on dam slope and criterion of the plastic zone to ensure the safety coefficient of tailings dam is feasible.