露天转地下开采对边坡稳定性的影响

露天转地下开采过程中诱发的边坡失稳将严重影响安全生产,主要原因是地下开采导致采空区覆岩应力重分布,并引起岩体的移动和变形,岩体强度降低,影响边坡稳定。为了研究露天转地下开采对边坡稳定性的影响,以某矿实际开采工程为例,运用MIDAS,FLAC~(3D)等数值模拟方法分别模拟了地下采区位于边坡的坡脚、坡中和坡外区3种条件下地下开采对边坡稳定性的影响机制,得出地下采区位于坡脚处开采会导致坡覆岩边坡滑移区范围最大,边坡失稳概率大;位于坡外区开采因上覆岩层沉陷使整体坡角减小,有利于边坡稳定;而位于坡中区开采时,边坡稳定状态介于两者之间。通过对该工程实例分析得到地下采区位于坡脚、坡中区时边坡安全系数不足,在坡外开采时边坡处于稳定状态。

Effect of Slope Stability during Transition from Open-pit and Underground Mining

In the process of transition from open pit to underground mining,slope instability will affect the safety in pro-duction seriously.The main reasons are that underground mining will cause stress redistribution,the displacement of rock mass, reduce the strength of rock mass and influence the slope stability.In order to study the impact of the transition from open pit to underground mining on the slope stability,and taking the actual mining project as a case,the numerical simulation systems MI-DAS,FLAC3D are adopted to simulate the influence mechanism of slope stability under three different mining locations of slope toe,slope back and out of slope.As the result,underground mining in slope toe will lead to maximum sliding area of cover rocks and large slope instability probability;At outside of slope,the settlement of the upper slope reduce the slope angle,which is good for the stability.At slope back,its slope stability falls in between above.The evaluation on the practical engineering showed that the safety factors of mining at slope toe and slope back are insufficient,but mining at outside of slope is in stable.