露天转地下开采方案优化及边坡稳定性分析

以孟家堡铁矿露天转地下开采的实际情况为工程背景，利用强度折减法和FLAC3D数值模拟方法，以塑性区贯通、计算不收敛及位移突变为失稳判据计算边坡安全系数，确定潜在滑移面，分析静态及开采扰动下的边坡稳定性；根据随采深下降的边坡破坏规律，对开采方案进行优化.分析结果表明，无开采扰动下边坡安全系数为194，满足稳定性要求；不留境界矿柱的无底柱分段崩落法地下回采过程中，覆盖层厚度要达到25m，其起到吸收并转移应力和减缓边坡能量耗散速度的作用.

Mining Scheme Optimization and Slope Stability Analysis for Transition from Open Pit to Underground Mining

Taking the transition from open pit to underground mining of Mengjiabao iron mine as engineering background according to the plastic zone connection， computation divergence and displacement discontinuity as instable criterion of landslide， the strength reduction method and FLAC3D were used to calculate slope safety factor， determine potential slip surface of the slope and analyze slope stability under the condition of static and dynamic underground mining disturbance. Depending on the slope failure law under the different mining depth， the mining scheme was optimized. The results shown that the slope safety factor without the mining disturbance is 194， meeting stability requirement. In process of underground mining using non floor pillar sublevel caving stoping， the thickness of covering layer must reach up to 25m. It plays an important role in absorbing stress， transferring stress and slowing the energy dissipation speed.