节理岩体边坡采动损伤与可靠性分析

为定量分析节理岩体边坡的采动损伤对边坡可靠性的影响,通过对大孤山铁矿下盘混合岩边坡进行现场勘测与模糊C均值聚类优化分析,确定了岩体2组优势节理的倾向、倾角、迹长和密度的随机分布参数。利用Hoek-Brown强度准则参数m和s与岩体质量分类指标GSI和扰动系数的关系,采用Monte-Carlo模拟抽样技术获得了节理岩体强度的随机分布参数。建立了节理岩体损伤与扰动系数D的联系,应用Kawarnoto损伤张量对采动损伤进行了数值分析,并根据Rosenblueth原理获得了扰动系数D以及反映时空效应和各向异性的岩体强度随机分布参数。基于此,定量分析了大孤山铁矿下盘混合岩节理岩体边坡采动损伤的时空变化特征及其对边坡稳定性的影响。结果表明,采场底标高从-87 m降至最终-450 m时,坡顶至-87 m水平同一高度滑弧可靠性指标相对下降7.7%,原因为采场下移导致节理岩体损伤加剧、强度降低所致,并且危险滑面逐渐向坡面偏移,与坡面近处岩体的损伤较大相关。

Reliability and damage analysis on jointed rock mass slope

The aim of this paper is to quantitatively evaluate the effect of mining-induced damage on the stability of joint rock slope.By means of site survey and fuzzy C-mean optimization algorithm,the random distribution parameters of the dip direction,dip angle,trace length and density of two dominant joint sets in footwall migmatite slope of Dagushan iron mine were obtained.Considering the relationships among Hoek-Brown parameters (m,s) and Geological Strength Index (GSI) and disturbance coefficient (D),the random distribution parameters of jointed rock mass strength were obtained by Monte Carlo method.After establishing the relationship between the damage and disturbance parameters of jointed rock mass,the Kawarnoto damage tensor was employed to carry out the numerical simulation of the mining-induced damage.Then the random distribution parameters (D) and rock mass strength with spatial-temporal distribution characteristics and anisotropy were obtained according to the Rosenblueth principle.The slope reliability index was calculated based on the strength parameters of rock mass with spatial-temporal distribution characteristics.The result shows that while the elevation of the stope bottom decreases from -87 m to -450 m,the reliability index of slip circle from the top of slope to -87 m level decreases 7.7% relatively.This is because that the increase of mining depth aggravates the damage in joined rock mass and weakens its strength.The potential slip surface gradually move to the slope surface,which has a greater correlation with the damage in rock masses near the slope.