Study On 3D Stability Of Open-Pit Mine Slope Based On Special-shaped Ellipsoid Sliding Surface

The determination of the critical slip surface of the slope and the solution of its safety factor are the key issues in the analysis of slope stability.In the past decade,the research of the three-dimensional limit equilibrium method(LEM)has achieved fruitful results,and its calculation is simpler and more efficient.In reality,most of the environment in which the slope is located is more complex,and the selection of the critical slip surface of the traditional three-dimensional slope is mostly symmetrical structure.In order to make the shape of the slope slip surface more realistic,the three-dimensional stability of the incompletely symmetrical special-shaped ellipsoid surface is studied,which has certain theoretical significance and practical application value.Aiming at the analysis of the stability of three-dimensional slope with special-shaped ellipsoid sliding surface,this paper transforms it into a parameter equation based on the general formula of special-shaped ellipsoid.Through geometric transformation in space,a special-shaped ellipsoid controlled by six parameters,including semi-major axisR_a,semi-widthR_b,semi-heightR_c,offset angleδand spatial displacement tx,tz,can be directly applied to three-dimensional slope.According to the incomplete symmetry characteristics of special-shaped ellipsoid,two kinds of three-dimensional slope sliding surface forms,type I special-shaped ellipsoid sliding surface with large upper and small lower and type II special-shaped ellipsoid sliding surface with small upper and large lower,are constructed by interpolation principle.By setting up the method of lithological column line,the sliding column of the special-shaped ellipsoid sliding surface under complex lithology is constructed.The three-dimensional residual thrust method is selected as the calculation method,and the genetic algorithm is the search method.The stability calculation program is developed based on the Auto CAD platform.Through two examples,the stability of standard ellipsoid sliding surface and two kinds of special-shaped ellipsoid sliding surface is compared and analyzed,and the feasibility of the method is verified.The type II special-shaped ellipsoid sliding surface is determined as the critical sliding surface of slope stability.The research results are applied to the practical engineering application of Shengli West No.2 Open-pit Coal Mine in Shengli Mining Area of Inner Mongolia.