厚煤层临近采空区侧回风巷水力压裂 切顶卸压技术研究

Hydraulic fracturing roof cutting and pressure relief technology of return airway in thick coal seam near goaf side

  • 摘要:
    目的 针对临近采空区侧工作面回风巷围岩变形严重、应力集中明显、周期来压显现剧烈等问题,
    方法 以某矿平均厚度4.5 m、埋深380~440 m的工作面为背景,采用数值模拟与现场工业性试验相结合的方法,研究了水力压裂切顶卸压对回风巷侧区段煤柱变形及应力分布的影响。
    结果 结果表明,未压裂条件下,区段煤柱最大变形量达1.6 m,煤壁帮部应力集中明显;水力压裂后,煤柱变形最大减小0.5 m,降幅50%,煤壁帮部应力最大降低32%。现场试验进一步验证了压裂后支架工作阻力平均降低16.5%,微震事件由“高能低频”向“低能高频”转化,日均频次上升46.0%,单次事件能量均值下降10.21%,回风巷底鼓减小约50%,端头悬顶实现随采随垮。
    结论 水力压裂切顶卸压技术显著改善了回风巷围岩应力环境与矿压显现特征,为类似条件下巷道围岩控制提供了有效技术途径。

     

    Abstract: Aiming at the problems of serious deformation of surrounding rock, obvious stress concentration and severe periodic weighting in the return airway of the working face near the goaf side, taking the working face with an average thickness of 4.5 m and a buried depth of 380~440 m in a mine as the background, the influence of hydraulic fracturing roof cutting and pressure relief on the deformation and stress distribution of coal pillar in the section of return airway side is studied by combining numerical simulation with field industrial test. The results show that under the condition of non-fracturing, the maximum deformation of the section coal pillar is 1.6 m, and the stress concentration in the coal wall is obvious. After hydraulic fracturing, the maximum deformation of coal pillar is reduced by 0.5 m, a decrease of 50%, and the maximum stress of coal wall is reduced by 32 %. The field test further verified that after fracturing, the working resistance of the support was reduced by 16.5% on average, the microseismic events were transformed from ' high-energy low-frequency ' to ' low-energy high-frequency ', the daily average frequency was increased by 46.0%, the average energy of a single event was decreased by 10.21%, the floor heave of the return airway was reduced by about 50%, and the collapse of the end hanging roof was realized with mining. The hydraulic fracturing roof cutting pressure relief technology significantly improves the stress environment and mine pressure behavior characteristics of the surrounding rock of the return airway, and provides an effective technical way for the control of the surrounding rock of the roadway under similar conditions.

     

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