In light of the complex and dynamic mechanical properties of evolving weak strata in open-pit mines, and the consequent difficulty of determining their mechanical parameters, this study uses the ultimate balance theory, along with the back analysis method combined with monitoring data on field displacement, to carry out parameter inversion using the FLAC3D numerical simulation software. The edge slope of a working pit of the Weijiamao open-pit mine was used as research object to this end. As the results obtained by the constitutive model were consistent with the field monitoring data, the evolving weak strata in the slope and the position of the landslide in the mine could be obtained. The landslide was directed northeast. The mechanism of the edge slope of the working pit was identified as unloading shear failure, and the feasibility of the method of parameter inversion was verified. The internal friction angle ϕ and cohesion C of evolving weak strata in the slope of the open-pit mine were also obtained, where this compensated for the deficiency of laboratory tests and enabled the transformation from qualitative to quantitative analysis. This can provide a reliable basis for the safe operation of open-pit mines.

鉴于露天矿中演化的弱地层的复杂而动态的力学特性，以及随之而来的确定其力学参数的困难，本研究采用极限平衡理论，结合反分析方法和现场位移监测数据，使用FLAC3D数值模拟软件进行参数反演。为此，以魏家茅露天矿工作井的边坡为研究对象。由于本构模型得到的结果与现场监测数据吻合，因此可以得到边坡中演化的弱地层和矿山中滑坡的位置。滑坡指向东北。工作坑边缘倾斜的机理被确定为卸荷剪切破坏，验证了参数反演方法的可行性。内摩擦角还获得了露天矿边坡中演化中的薄弱地层的ϕ和内聚力C，这弥补了实验室测试的不足，并使从定性分析向定量分析的转变成为可能。这可以为露天矿的安全运行提供可靠的基础。