采空区影响下穿层巷道变形特征及支护技术研究

Study on deformation characteristics and support technology of cross layer roadway under the influence of goaf

针对梁北矿在采空区下近距离掘进-550 m水平东翼开拓巷道围岩不易稳定的问题,采用数值模拟方法分析了相邻2个不同时间开采的工作面形成的采空区和煤柱对开拓巷道附近围岩的应力分布规律和变形特征;并基于多层次耦合承载结构的支护原理,给出了相应的变形控制对策和支护方案,在现场进行了应用。研究结果表明:随着工作面的推进,采空区底板岩层原岩应力恢复区由采空区中部向四周扩散,塑性破坏区呈“倒马鞍”状分布;穿层巷道受邻近未稳定采空区垮落岩层逐步压实扰动过程产生的应力和煤柱应力集中产生的影响,塑性破坏区呈非对称分布。基于巷道围岩破坏形成破碎区、塑性区和弹性区的分区特征,提出充分利用内外承载体形成多层次耦合承载结构的支护对策;采用“高强锚网索+浅深部围岩分次注浆+喷浆”多层次耦合控制技术,在现场取得了良好的应用效果。

Aiming at the problem that the surrounding rock of the advancing roadway at the east wing of-550 m level is not easy to be stable when the tunnel is advanced in a short distance under goaf in Liangbei Mine,the stress distribution law and deformation characteristics of the goaf and coal pillar formed by two adjacent working faces at different times on the surrounding rock near the advancing roadway were analyzed by numerical simulation.Based on the support principle of multi-level coupling bearing structure,the corresponding deformation control countermeasures and support schemes were proposed and applied in the field.The results show that with the advance of the working face,the stress recovery zone of the raw rock of the floor strata in the goaf diffuses from the middle of the goaf to the surrounding areas,and the plastic failure zone is distributed in an“inverted saddle”shape;under the influence of the stress produced by the disturbance process of progressive compaction of the adjacent unstable goaf and the stress concentration of the coal pillar,the plastic failure zone of the tunnel is asymmetrically distributed;based on the zoning characteristics of broken zone,plastic zone and elastic zone formed by the failure of roadway surrounding rock,the supporting strategy of making full use of internal and external support to form multi-level coupled bearing structure is put forward.The multi-level coupling control technology of“high strength anchor-mesh-cable+reinforcement of shallow and deep surrounding rock by staged grouting+shotcreting”in shallow and deep surrounding rocks has achieved good application results in the field.