露天转地下开采不同坡高影响下覆岩采动响应特征研究

Research on Mining Response Character of Underground Overlying Strata under Different Slope Heights during Transition from Open Pit to Underground Mining

以云南滇池周边典型的缓倾斜含软弱夹层中厚磷矿床露天转房柱法地下开采为研究背景,通过现场勘查取样和室内岩石力学试验,基于AutoCAD、ANSYS和FLAC3D等软件进行耦合建模,对倾角为45°时边坡高度为50 m和80 m的上覆岩层位移与应力响应特征进行动态模拟和对比分析。研究结果表明:在露天终了边坡为50 m时,地下开采对覆岩影响相较80 m坡高小,此时围岩相对稳定,塑性区面积较小,整个岩体处于相对稳定状态。露天终了边坡为80 m时,开采对覆岩的扰动较大,回采完毕后矿柱处于临界破坏状态,塑性区较50 m坡高进一步发育并延伸至坡面,不利于矿山的安全稳定。研究成果确定了该矿山露天终了边坡的合理高度范围,对矿山的安全、经济生产具有重要的理论指导意义。

Based on the engineering background of open pit mining transiting to the underground mining of room and pillar method for the typical gently-inclined soft interlayer medium-thick phosphate rock bed surrounding Yunnan Dianchi lake,through the field survey sampling and indoor rock mechanics tests,multi-software coupled modeling was made,including CAD,ANSYS,FLAC3 D etc.,to realize dynamic simulation and comparative analysis on the displacement and stress response characteristics of overlying strata with a slope height of 50 m and 80 m when the inclination angle is at 45°.The results show that when the final slope is 50 m at the open pit,the impact of underground mining on the overburden is smaller than that of the 80 m final slope.In this case,the surrounding rock is relatively stable,the plastic zone area is small,and the whole rock mass is in a relatively stable state.When the final slope at the open pit is 80 m,the mining has a great disturbance to the overburden rock.After the mining,the ore pillar is in a critical failure state,and the plastic zone further develops and extends to the slope compared with that of 50 m,which is not conducive to the safety and stability of the mine.Based on this study,the reasonable height range of the slope was determined,which has important theoretical guiding significance for the safety and economic production of the mine.