排土场散体物料抗剪强度的安全系数反演分析

在初步判断排土场边坡所处的稳定状态的基础上设定一个安全系数,利用安全系数反演计算排土场散体物料的抗剪强度参数。以常用的Bishop圆弧法和余推力折线法作为排土场边坡稳定性计算的基本方法,构建非线性方程组,迭代求解,同时反演出排土场散体物料的抗剪强度参数。针对西南地区某个大型露天矿排土场边坡进行了实际反演分析,得出:含第四系表土较多的细粒散体岩石,反分析黏聚力c比三轴试验小0.026 MPa,而摩擦角φ则大3.94°;以粗粒土为主的坚硬辉长岩,反分析黏聚力c比三轴试验大0.021 MPa,而摩擦角φ则小4.06°。虽然2种散体岩土反演分析与试验结果都有差异,但是通过安全系数反演分析的结果,更能从整体上把握排土场散体物料的力学强度参数。该方法不像室内试验和现场试验那样受排土散体物料不均匀和离散性的影响,同时获得的抗剪强度参数可以作为后期动态排土规划稳定性分析的依据。

Inversion Analysis of Safety Factor on Shear Strength of Waste Dump Bulk Materials

On the basis of preliminary judging the steady state of dump slope，a safety factor is set，the shear strengths of waste dump bulk materials are inversed with the safety factor.With the use of the common Bishop method and Residual thrust method，the nonlinear equation group is built to make the iterative solution.Meanwhile，the shear strengths of waste dump bulk materials are calculated out.Aiming at the actual inversion analysis on dump slope of a large open pit mine in southwest China，it is concluded that:for fine-grained granular rock with more quaternary topsoil，its cohesion c by inversion analysis is smaller than triaxial test by 0.026 MPa，but friction angle φ is bigger by 3.94°；For hard gabbro with coarse grained soil as the main，its cohesion c by inversion analysis is bigger than that at triaxial test by 0.021 MPa，but its friction angle φ is smaller by 4.06°.Although the two kinds of bulk materials have different inversion analysis and experiment results，the inversion analysis results based on the safety factor can better grasp the shear strength parameters of waste dump bulk materials as a whole.This method is superior to the indoor test and field test which are affected by the unevenness and discreteness of bulk materials.At the same time，the shear strength parameters obtained can be used as the basis of dynamic stability analysis in the late dump planning.