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冲击地压矿井近距离特厚煤层综放工作面合理推进速度研究

Study on reasonable advancing speed of fully-mechanized top-coal caving face in mining contugous  extra-thick coal seams in rockburst mine

  • 摘要: 针对工作面推进速度过快易诱发冲击地压的问题,以宽沟煤矿近距离特厚煤层W1123综放工作面开采为背景,采用数值模拟及理论分析的综合分析方法,通过研究近距离特厚煤层不同推进速度影响下煤岩采动应力、能量演化特征,分析不同推进速度下覆岩运移破断特征,评估不同推进速度影响下煤岩体冲击危险性,综合研究确定了工作面的合理推进速度。研究结果表明:工作面开采引起的超前支承压力峰值应力随推进速度增加呈明显的非线性递增趋势,且其增幅逐渐增加,在实体煤下回采应力水平明显高于采空区下,超前支承压力呈现明显的双峰值现象;随推进速度提高,覆岩初次破断距及覆岩内积聚的弹性能显著增加,应变能密度也随之逐渐升高;覆岩位移变化量随推进速度增加急剧增加,破坏范围广,呈现出明显的非连续变形特征,同时推进速度愈快,覆岩破断影响范围越广,运移演化愈剧烈;随推进速度提高,工作面煤岩冲击危险性指数随之明显增大,且在实体煤下回采时的危险性远大于采空区下,其上覆煤层开切眼后方100 m范围冲击危险性指数随推进速度提高急剧升高,为冲击影响的高危险区域。数值模拟研究结果综合认为W1123工作面在保证安全高效生产前提下,相对适宜的推进速度应不大于6.4 m/d。研究结果为近距离煤层冲击地压矿井的安全高效开采提供了科学指导。

     

    Abstract: In view of the rock burst problem caused by too fast advancing speed of the working face, taking the mining of W1123 fully mechanized top coal caving face in contugous  extra-thick coal seam in Kuangou Coal Mine as the background, the comprehensive analysis method of numerical simulation and theoretical analysis is adopted. By studying the mining stress and energy evolution characteristics of coal and rock under the influence of different advancing speeds, the characteristics of overlying strata movement and breaking at different advancing speeds are analyzed, and the burst risk of coal and rock mass under the influence of different advancing speeds is evaluated. The reasonable advancing speed of the working face is determined by comprehensive research. The results show that the peak stress of front abutment pressure caused by mining in the working face shows an obvious nonlinear increase trend with the increase of advancing speed, and its increase rate gradually increases. The mining stress level under solid coal is obviously higher than that under goaf, and the front abutment pressure shows an obvious double peak shape. With the increase of advancing speed, the initial breaking distance of overburden and the elastic energy accumulated in overburden obviously increase, and the strain energy density also gradually increases. The displacement of overlying strata increases sharply with the advancing speed, and the damage range is large, showing obvious discontinuous deformation characteristics. At the same time, the faster the advancing speed, the larger the influence range of overlying strata breakage, and the more severe the migration evolution. With the increase of advancing speed, the burst risk index of coal and rock in working face increases obviously, and the risk of mining under solid coal is far greater than that under goaf. The burst risk index of 100 m behind the setup room of overlying coal seam rises sharply with the increase of advancing speed, which is a high-risk area with bursts. According to the results of numerical simulation, it is considered that the relative suitable advancing speed of W1123 working face should be no more than 6.4 m/d on the premise of ensuring safe and efficient production. The research results provide scientific guidance for safe and efficient mining of rock burst prone mines in coal seams occur in close proximity.

     

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