基于PFC2D岩质边坡稳定性分析的强度折减法

Strength Reduction Method for Rock Slope Stability Analysis Based on PFC2D

基于颗粒流离散单元法,将强度折减法引入到边坡稳定性研究中,可以解决应用连续变形分析方法研究存在的缺陷.取特定平均不平衡力比率作为边坡失稳与否判断准则,将颗粒间粘结强度及摩擦系数进行折减,以边坡岩体出现失稳破坏且断裂面贯通作为失稳判断准则,一方面能够对边坡局部危险区域予以定性预测,另一方面监测边坡变形到破坏的失稳过程,最终定量分析边坡稳定性.结合黑山铁矿现场边坡稳定研究实例,分别研究了边坡开挖扰动前后的边坡变形特征,得到开挖前后边坡安全系数分别为1.803和1.183,与预期结论一致.

Strength reduction method was implemented into the particle flow code（PFC2D） that is based on discrete element method（DEM）,to tackle the difficulties for the slope stability analysis based on continuum mechanics.In this regard,the ratio of average unbalanced mechanical force as the failure criteria to judge the unstable failure of slope,the cohesive force and frictional coefficient were reduced to capture the coalescence of fractures,this approach could not only qualitatively judge the local failure of the slope,but also monitor the complete instable failure process of the slope.By means of strength reduction method,safety factor could be finally calculated automatically.The proposed method was applied to the rock slope stability analysis of Heishan metal mine.Slope safety factors under different conditions were obtained respectively.The safety factors of 1.803 and 1.183 before and after the excavation of slope were obtained respectively,which agree with the expectations.