Stability Analysis Of Tailing Dam Structure Based On Finite Element Limit Equilibrium Method

Tailings dam accidents not only make the tailings loss, environmental pollution, seriously they would threaten the lives and property of downstream residents in the reservoir area. Therefore, the stability of the tailing dam has a very important practical significance.Currently, the tailing dam stability analysis is still to be regarded as a complex slope, and still use the traditional theory of the soil mechanics for analysis. There are varieties of slope stability analysis methods, each method has its own characteristics and scope of application. Limited equilibrium slice method and finite element method (finite element shear strength reduction method and finite element limit equilibrium method) deterministic method have been widely used. In the traditional limit equilibrium method, the landslide is considered as a rigid body, without regarding to the soil stress-strain relationship. And in the calculation of the slope safety factor, the location and shape of the sliding surface is assumed previously. And then find the minimum safety factor and the most dangerous sliding surface through the spreadsheet. This will affect the calculation accuracy and efficiency. The finite element method as a widely used numerical method, it can not only meet the full permission of the static, strain compatibility and stress-strain constitutive relation, but also simulate the complex geotechnical engineering, water conservancy project and soil structure.Under the condition of plane strain, finite element limit equilibrium method is applied to evaluate the stability for tailing dam. This method can be better combined with characteristics of the limit equilibrium analysis methods and finite element stress analysis. This paper does the mainly work at the following aspects based on finite element limit equilibrium method:Firstly, the finite element limit equilibrium method is applied to the tailing dam stability analysis for the first time. The overall stress field distribution obtained is based on the non-associated flow rule, elastic-perfectly plastic constitutive model and the Mohr-Coulomb yield criterion. By using four-node plane strain element is to get the whole stress field distribution. Then the most dangerous location of slip surface and the corresponding minimum safety factor are determined by2d finite element limit equilibrium method slope stability analysis software(2DSTABFEM for short). First of all, for a single uniform slope, the contrast results show that the applicability of the method in slope stability analysis and replicability among the stability methods:finite element limit equilibrium method, limited equilibrium slice method and finite element shear strength reduction method.Secondly, the influence factors of tailings dam stability are analyzed. Considered the single homogeneous slope under the seepage, earthquakes, and the two simultaneously operating conditions separately, the differences of safety factor quantity, slip surface shape and location between stability method based on finite element limit equilibrium method, limited equilibrium slice method and finite element shear strength reduction method are compared and studied.Finally, an example of stability analysis for Nanjing some tailing dam engineering practice is proposed. The differences of safety factor quantity, shape and location of slip surface among stability methods:finite element limit equilibrium method, limited equilibrium slice method and finite element shear strength reduction method, are compared and studied in the normal, flood and special conditions. The safety assessment of tailing dam is made by using finite element limit equilibrium method. And the results can provide a reliable basis and technical support for the safety of the design and construction of tailing dam.