深部沿空切顶成巷围岩稳定性控制对策

Control Countermeasures of Surrounding Rock in Deep Gob-side Entry Retaining by Cutting Roof

基于沿空切顶成巷技术原理,以城郊煤矿深部工作面无煤柱开采为背景,综合运用力学分析模拟计算和现场试验等方法,对深部切顶成巷围岩控制关键对策进行深入研究。结果显示:切顶留巷顶板在侧向形成短臂梁结构,降低了巷旁支护体所受压力,切缝范围内岩层垮落后碎胀充填采空区,使留巷顶板下沉量降低了约50%。采空区侧顶板为切顶巷道围岩变形的关键部位,需进行加强支护;深部切顶巷道实体煤帮塑性区范围大,通过煤帮锚索支护技术可将浅部锚杆承载层锚固在弹性区稳定煤体中;深部切顶成巷来压速度快、强度大,巷内单体支柱易造成冲击破断,采用高阻力液压支架巷内临时支护时可较好地抵抗深部强动压;巷旁刚性挡矸装置因无法适应深部围岩大变形而受压弯曲破坏,深部切顶巷道巷旁挡矸结构需实现一定的竖向让位卸压方可与顶底板协调变形。在研究的基础上提出恒阻锚索关键部位支护+可缩性U型钢柔性让位挡矸+巷内液压支架临时支护+实体煤帮锚索补强的深部切顶成巷联合支护技术,并进行现场工业性试验。现场监测结果表明:留巷围岩在滞后工作面约290 m时基本稳定,且稳定后各项指标满足下一工作面使用要求。

Based on the technical principle of gob-side entry retaining formed by advanced roof cutting, this study takes non-pillar mining in deep working face of Chengjiao coal mine as the research background, and comprehensively uses methods of mechanics analysis, numerical calcula- tion and field measurement to investigate the control countermeasures of surrounding rock in deep gob-side entry retaining formed by cutting roof. The roof of gob-side entry retaining induced by cutting roof formed a cantilever beam above the roadway and the pressure on the roadside sup- port body was reduced. The broken expand gangue formed by cutting the roof filled the goaf good, which reduced the displacement of roof sink- ing by about 50%. It should be noted that the side roof of gob area is the key part for surrounding rock deformation in roof cutting roadway and needs to be intensively supported. Note that the plastic zone of solid coal rib in deep roof cutting roadway is large and the shallow bolt bearing layer can be anchored in the stable coal body in the elastic zone using the anchor coal rib support technology. The pressure of deep roof cutting roadway has a fast speed and is very fierce after mining, leading to the damage of single prop in the roadway. Utilizing the hydraulic supporter with high resistance as the temporary support can resist deep strong dynamic pressure and the impact load. The roadside rigid block gangue exper- ienced compression bending failure due to its inability to adapt to the large deformation. In order to have consistent deformation with the roof and floor, the roadside block gangue in deep roof cutting roadway should achieve a certain vertical sliding deformation. The support technology com- bining gob-side roof constant resistance large deformation bolt, contractible U section steel block gangue, entry-in hydraulic support and solid coal side anchor rope was proposed, and the industrial field tests were conducted. The field monitoring results show that the surrounding rock of deep gob-side entry retaining formed by cutting roof is basically stable about 290 m behind the working face and all of the indexes after roadway stabilization can meet the operational requirements of next coal mining face.