某山坡露天矿边坡稳定性的FLAC3D研究

某山坡露天矿,原设计的最终边坡角约为46°。为了探索最终边坡角的合理性,应用快速拉格朗日有限差分法FLAC3D在摩尔-库伦准则下搜索该岩质山坡露天边坡的潜在受拉区,判定其稳定性。结果表明:经济合理的最终边坡角是50°38';应用8 m长的锚索加固局部台阶可减小其潜在受拉区中的拉应力;并段将减小边坡的稳定性;爆破开挖时的同段最大装药量与爆距对边坡稳定性影响明显。该方法确定最终边坡角技术可行,它适用于研究岩质边坡的稳定性,克服了用极限平衡法研究边坡稳定性必须事先假定滑动面的弱点。

Approach to attaining the stability of an open-pit mine by using the fast Lagrangian finite difference method

The paper is aimed to make an investigation of the potential tensile zone of the rock open-pit sloping mines and analyze their stability by using the fast Lagrangian finite difference method (FLAC3D) with the Mohr-Coulomb criteria,so as to explore the ultimately rational pit slope angle of such mines,whose original slanting angle of the open pit mine had been designed at an angle of about 46°.To solve the problem,we have,first of all,built up 8 numerical models with 8 different ultimate pit slope angles to compare the actual size of the tensile zone and the value calibration of the tensile stress.The results we have gained from the comparison prove that the economic and rational pit slope angle to be approved should be set at about 50°38′.And,then,we have managed to build up a corresponding numerical model with the parallel step bench form with the ultimate pit sloping angle being 50°43′.At the same time,we have also conducted a slope stability simulation test with the static analysis.Taking into account the safety of the slope,we have recommended the slope to be built up without the parallel step form.And,thirdly,we have carried out a static analysis of the safety-involving factors of such rock hillside open-pit slope,believing that it would be possible to reduce the tensile stress in the potential tensile zone if the local step slopes can be reinforced by using an eight meters' long anchor cable under the condition that the safety factor should be made to reach 1.3.Last of all,we have also done a dynamic analysis for the slope blasting extraction by applying the calibrated blast pressure to the extraction face in the form of pressure generated by the ANSYS/LS-DYNA.The results of the analysis demonstrate that the maximum charge of the same millisecond blasting section for the excavation and the blasting distance should be taken as the two main factors that may affect the stability of the slope.Thus,the method we have developed in this paper for testing the stability of the open pit rock mine can be successfully made for reference to the other similar mines in favor of overcoming the weaknesses of the currently existing limited equilibrium method for the similar slope mines.