沿空掘巷小煤柱合理留设及锚注支护优化研究

针对许疃煤矿3238工作面风巷沿空掘进施工位于上一采空区顶板断裂形成的应力集中区,且局部老空区水长期浸泡小煤柱,造成施工巷道滞后性变形显著这一现状,通过现场试验、实验室测试,并结合理论分析及数值模拟,研究了不同小煤柱留设宽度下围岩应力分布及位移变化规律、小煤柱护巷机理及沿空侧注浆方案、参数优化设计。综合研究结果表明:在相同的地质及采矿条件下,3238风巷合理的小煤柱宽度应为5m;同时对该巷道“锚-网-索-梁-注”联合加固支护方案进行了设计;由窥视结果确定了在掘进15~20天时(距掘进头60~80m)进行注浆可充分发挥煤柱注浆效果;巷道支护实践及矿压观测得出,在掘巷支护20天后围岩变形量相对较小、锚杆受力趋于稳定、顶板离层量逐步减小,可满足安全生产要求。最终形成了一种适合于小煤柱沿空掘巷锚注加固技术方案,为小煤柱沿空掘巷支护提供了实践和理论依据。

For the 3238 working face of Xutuan coal mine,the driving along the goaf is located in the stress concentration area formed by the roof fracture of the last goaf,and the small coal pillars are soaked in the water of the local old goaf for a long time,resulting in significant lag deformation of the construction roadway,the stress distribution of the surrounding rock under the different width of the small coal pillars is studied through field test,laboratory test,theoretical analysis and numerical simulation And displacement change rule,small coal pillar protection mechanism,grouting scheme along the goaf side,parameter optimization design.The comprehensive research results show that under the same geological and mining conditions,the reasonable small coal pillar width of 3238 air tunnel should be 5 m;at the same time,the"bolt net cable beam injection"joint reinforcement and support scheme of the tunnel is designed;from the peep results,it is determined that the coal pillar grouting effect can be brought into full play when the grouting is carried out during 15~20 days of driving(60~80 m from the excavation head);the tunnel support practice and mine pressure observation result after 20 days,the deformation of surrounding rock is relatively small,the stress of bolt tends to be stable,and the amount of roof separation is gradually reduced,which can meet the requirements of safety production.Finally,a kind of bolt and injection reinforcement technology scheme suitable for small coal pillar driving along goaf is formed,which provides practical and theoretical basis for small coal pillar driving along goaf.