极近距离煤层采空区下巷道围岩支护技术研究及应用

    Research and application of surrounding rock support technology for roadways in extremely close range coal seam goaf

    • 摘要: 针对五虎山煤矿极近距离煤层巷道变形控制难题,分析了巷道顶底板岩层结构分布与围岩原位强度及地应力场分布规律,研究了极近距离煤层巷道围岩变形特征及其影响因素,采用理论计算与数值模拟分析得出了上煤层开采后底板破坏深度及围岩稳定性,揭示了极近距离煤层巷道变形破坏机理,提出了相应的变形控制技术及方案,开展了井下工业性试验。研究结果表明:五虎山煤矿极近距离煤层巷道变形主要表现为顶板下沉及巷帮肩窝内挤,矿井最大水平主应力与巷道夹角为43.0°~76.1°,夹角大不利于巷道顶底板岩层稳定性;下煤层顶板岩层膨胀性黏土矿物成分含量高达50%以上,加剧了顶板岩层的膨胀变形;上煤层开采后底板最大破坏深度28.1 m,远大于煤层间距,极近距离煤层巷道位于上覆遗留煤柱高应力区外,围岩整体处于应力降低区,下煤层顶板岩层仍具有较好的完整性及锚固特性。通过提高巷道初期支护强度、保持围岩自身稳定性是极近距离煤层巷道围岩变形控制的关键。基于此确定了合理的锚杆预紧力参数,制定了高预应力锚杆支护与架棚主被动联合支护方案,井下工程应用后巷道围岩变形较原支护巷道显著减小,两帮最大移近量70.8 mm,顶底板最大移近量为104.5 mm,表明采用高预应力锚杆支护与架棚主被动联合支护可以有效控制五虎山煤矿极近距离煤层变形。

       

      Abstract: In response to the difficult problem of deformation control in the extremely close range coal seam roadway of Wuhushan Coal Mine, the distribution of rock structure and in-situ strength of surrounding rock, as well as the distribution law of in-situ stress field, are analyzed. The deformation characteristics and influencing factors of the surrounding rock in the extremely close range coal seam roadway are studied. Theoretical calculation and numerical simulation analysis are used to determine the depth of floor failure and stability of surrounding rock after upper coal seam mining. The deformation and failure mechanism of the extremely close range coal seam roadway is revealed, and corresponding deformation control techniques and schemes are proposed. Industrial tests are carried out underground. The results show that the deformation of the extremely close range coal seam roadway in Wuhushan Coal Mine is mainly manifested as roof subsidence and shoulder compression of the roadway. The maximum horizontal principal stress of the mine is at an angle of 43.0°-76.1° with the roadway, which is not conducive to the stability of the roof and floor rock layers. The content of expansive clay minerals in the lower coal seam roof rock layer is over 50%, which exacerbates the expansion deformation of the roof rock layer. The maximum depth of damage to the floor after upper coal seam mining is 28.1 m, which is much greater than the spacing between coal seams. The coal seam roadway is located very close to the overlying residual coal pillar high stress zone, and the surrounding rock is in a stress reduction zone as a whole. The lower coal seam roof rock layer still has good integrity and anchoring characteristics. Improving the initial support strength of the roadway and maintaining the stability of the surrounding rock is the key to controlling the deformation of the surrounding rock in extremely close range coal seam roadway. Based on this, reasonable pre tensioning parameters for anchor bolts are determined, and a high prestressed anchor bolt support and active passive support scheme for scaffolding are developed. After the application of underground engineering, the deformation of the surrounding rock of the roadway is significantly reduced compared to the original support roadway, with a maximum displacement of 70.8 mm for the two sides and 104.5 mm for the roof and floor. This indicates that the use of high prestressed anchor bolt support and active passive support for scaffolding can effectively control the deformation of the extremely close range coal seam in Wuhushan Coal Mine.

       

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