深部非对称采空区煤层大巷冲击机理及防控

Mechanism and prevention of rockburst in deep asymmetric goaf areas coal seam main roadway

  • 摘要:
    目的 随着煤层大巷使用频率的增加,煤层大巷冲击地压灾害发生频率日益递增,特定条件下煤层大巷冲击地压发生机理和差异化防控措施的研究,对深部煤炭安全开采具有重要意义。
    方法 基于内蒙古某矿强冲击煤层大巷,采用现场实测、理论分析、FLAC3D模拟等方法研究了煤层大巷两侧非对称采空区结构演变过程中巷道围岩应力和覆岩结构演化规律,构建了大巷冲击风险判别指标,揭示了大巷冲击失稳机制,提出了针对性防控思路。结果和结论采空区面积和覆岩结构演化是影响煤层大巷区域冲击风险的主要因素,且非对称采空区结构形成会进一步其冲击风险。非对称采空区结构演化过程中垂直应力逐步演变为最大主应力,并在大巷煤柱区呈“双峰”分布;随着大巷西侧采空区面积的增大,大巷围岩垂直应力持续增大,应力增量先增大后减小,其中回风大巷一直位于西侧应力峰值区,峰值应力38.7 MPa;大巷煤柱区覆岩空间结构由“非对称T”形逐步转变为“对称T”形,大巷两侧岩层活动的互馈效应增强。煤层大巷受两侧采空区结构变化影响,大巷围岩应力集中、围岩损伤增大,大巷局部围岩应力超过其临界破坏载荷后向巷道内部瞬间位移,诱发冲击地压。煤层大巷顶、底板冲击破坏临界载荷分别为32.8、24.7 MPa,潜在冲击风险区域随非对称采空区演化逐渐增大。制定了以回风大巷位置优化、顶板深孔爆破等为主的区域与局部一体的“降载−卸压−支护”协同防控方案,经检验可以有效降低冲击风险。研究结果可对类似开采条件下煤层大巷冲击地压防治提供有益借鉴。

     

    Abstract: With the increasing frequency of coal seam roadway usage, the occurrence of rockburst disasters has shown a rising trend. Research on the mechanisms of rockburst and differentiated prevention measures for coal seam roadways under specific conditions holds significant importance for the safe extraction of deep coal resources. Taking the panel roadways of a mine in Inner Mongolia as the study site, this work combines on-site measurement, theoretical calculations and FLAC3D numerical modelling to examine the evolution of both the surrounding rock stress field and the overburden structure during the progressive formation of asymmetric goafs on either side of a coal main seam roadway. An index for identifying rockburst risk in the roadway is established, the instability mechanism governing roadway rockburst is revealed, and the targeted prevention strategy is formulated. The research results indicate that the goaf area and the evolution of overburden structure are the primary factors influencing rockburst risk in coal seam roadway areas, and the formation of an asymmetric goaf structure further increases this risk. During the structural evolution of asymmetric goaf areas, the vertical stress progressively becomes the maximum principal stress and exhibits a “twin-peak” distribution within the coal pillar zone adjacent to the main roadway. The vertical stress acting on the surrounding rock of the existing roadways continues to rise, with the stress increment first increasing and then decreasing; the return airway remains within the western stress-peak zone, where the maximum stress reaches 38.7 MPa. In the transverse profile, the overburden structure above the coal pillar zone evolves from an “asymmetric T” shape into a “symmetric T” shape, intensifying the mutual feedback of strata movement on both sides of the roadway. Owing to the structural changes in the goaf areas on either side, the roadway’s surrounding rock experiences intensified stress concentration and increased damage; once the localized stress exceeds its critical failure load, the rock displaces instantaneously toward the opening, triggering rockburst. The critical loads for rockburst failure of the roadway roof and floor are 32.8 MPa and 24.7 MPa, respectively. As the asymmetric goaf evolves, both the potential rockburst risk and the extent of its manifestation continue to expand. A coordinated prevention and control scheme integrating “load reduction – pressure relief – support” at both regional and local levels was formulated, focusing on measures such as optimizing the location of the ventilation roadway and implementing deep-hole roof blasting. Field validation has demonstrated that this approach effectively reduces rockburst risk. The findings can provide a valuable reference for preventing rockburst in coal seam roadways under similar mining conditions.

     

/

返回文章
返回