房柱式采空区影响下露天端帮煤开采安全控制技术

Safety control technology of open-pit end wall coal mining under influence of room pillar gob

为了保障房柱式采空区影响下露天端帮煤的安全高效开采,采用瞬变电磁探测技术探明房柱式采空区与边坡的空间关系,运用自主研发锚固式多点位移计对端帮煤开采过程中的房柱式采空区顶板岩体进行了立体监测,并采用数值模拟对边坡临空面卸荷应力和顶板岩体垂直应力耦合作用下的岩体稳定性进行了分析,对端帮煤的开采方案进行了优化。研究结果表明:瓷窑塔矿南端帮存在复合采空区,其稳定性主要受3-1煤采空区影响,采空区距离2-2煤工作帮纵向埋深为30 m,嵌入露天采场横向距离为50 m;横向上各监测点呈现出"稳定-增长-再稳定"的位移趋势,远端帮监测点位移变化较为稳定;纵向上端帮煤的开采对采空区顶板浅层15 m以内的岩体影响较大,浅层顶板位移出现急剧增大的离层现象,离层区域出现是采空区顶板活化移动的前兆;端帮煤的开采使边坡出现滑移趋势,煤柱帮角岩体由边坡内及外出现"链式集中效应",采空区上部岩体出现明显的卸荷应力区域,埋深为15 m,端帮煤开采应采取保留端帮煤区段2,将台阶高度由15 m降为12 m的开采方案。

In order to ensure the safe and efficient mining of open-pit end coal under the influence of room pillar gob,the spatial relationship between the room and pillar gob and the slope was verified through TEM(Transient Electromagnetic Detection Technology),and the self-developed anchored multi-point displacement meter pair was used.The roof rock mass in the room-pillar gob during the end coal mining process was monitored three dimensionally,the rock mass stability under the coupling effect of the unloading stress of the slope and the vertical stress of the roof rock mass was was numerically simulated and the mining scheme was optimized.The results show that there were compound gob beams in the southern end of Ciyaota Mine,whose stability was mainly affected by the No.3-1 coal seam.The distance between the gob and the No.2-2 coal seam working side was 30 m in the buried depth,50 m in the lateral distance embedded in the open pit.In the transverse direction,each monitoring point presents a displacement trend of"stable-growth-restable",and the displacement change of the remote monitoring point was relatively stable;the opening of the longitudinal upper side coal mining had a great influence on the rock mass within 15 m of the shallow roof of the gob,and the shallow roof displacement shows a sharp increase in separation.The occurrence of the separation area was the precursor of the activation and movement of the roof of the gob;the mining of the end wall coal cause the slope to slide.The"corner chain concentrated effect"of the coal pillar appears in the slope from inside and outside,the upper rock mass of the gob has obvious unloading stress area,and the buried depth is 15 m,and the mining plan adjusted to reserve section 2 and reducing the bench height from 15 m to 12 m.