基于有限元强度折减法的露天磷矿高边坡稳定性分析

High slope stability analysis for the phosphorus open-pit mine based on the finite element strength gradual reduction method

针对尖山磷矿开采实际情况,利用ANSYS有限元分析软件建立了考虑重力载荷作用的高边坡体稳定性分析数值模型,运用强度折减法折减边坡岩体的黏聚力和内摩擦角,根据计算结果分析尖山磷矿东采区高边坡在重力作用下的稳定情况。结果表明:当折减系数由1.33增加到1.34时,高边坡体的位移、塑性应变发生突变,通过边坡失稳的主要判据判定目前尖山磷矿东采区高边坡的安全系数为1.33,边坡稳定。

The paper is aimed at offering a high slope stability analysis for a phosphorus open-pit mine based on the finite element strength gradual reduction method. In this paper,we have adopted the idealistic elastoplastic model in accordance with the situation of Jianshan phosphorus open-pit mine by simplifying the calculation model as the constitutive model of the rock slope into a plane strain question. To be brief,we have simplified the entire slope as a series of sandy dolomites by setting up the high slope stability analysis numerical model by using ANSYS finite element analysis software. In so doing,we prefer to take the model merely as the slope rock gravity load,with no regard to the effect of the tectonic stress field. In so doing,it would be possible to reduce the cohesion and internal friction angle of the slope by using the strength reduction method. And,then,we have managed to work out the high slope stability of the eastern area of the mine under the action gravity based on the results that have so far been gained,so as to provide a guide for the subsequent mining production. The results of our calculation show that the horizontal displacement of the high slope tends to increase with the increase of the strength reduction factor Fs,with the maximum value distribution of the horizontal displacement being shifted from the slope middle part to the middle step. And,as long as the plastic strain of high slope increases gradually,the plastic strain zone from the foot of the slope towards the top of the hill slope may tend to increase gradually,too. Furthermore,when the reduction factor increases from 1. 33 to 1. 34,the mutation of the maximum horizontal displacement would occur in the middle part of the slope,leading to accelerating the horizontal displacement and the mutation of the plastic strain of high rock,with the plastic deformation zones coming up together. Then,according to the criteria of slope failure,it can be inferred that the slope is likely to be destroyed at the moment,which may confirm that the safety factor of east mining area in the open-pit mine should be equal to 1. 33.