特厚放顶煤极窄煤柱巷道切顶应力转移规律及控制研究

Stress transfer law and control of roof cutting in entry with extremely narrow coal pillar in extra-thick top-coal caving conditions

  • 摘要: 针对特厚放顶煤极窄煤柱巷道应力高、变形大和控制难的问题,分析了极窄煤柱支撑力与切顶长度和切顶角度之间的关系,对比分析了不同切顶方案极窄煤柱巷道顶板及煤柱应力分布特征及变形演化规律,提出了特厚放顶煤极窄煤柱巷道围岩“切−支−注”协同控制技术。分析结果表明:特厚综放工作面沿空巷道切顶卸压后,极窄煤柱支撑力随着切顶长度和倾角增加而逐渐减小,且减小幅度逐渐增大;增加切顶长度和切顶角度,使得煤柱内距底板不同高度处垂直应力和垂直相交点位置均向着巷道方向转移,有利于煤柱稳定性管理和控制。现场应用结果表明,采用协同控制技术后,极窄煤柱巷道最大位移量仅为269.03 mm,煤柱侧和实体煤侧围岩最大位移量分别为220.18 mm和195.36 mm,巷道底板最小位移量为92.83 mm,围岩变形得到了有效控制,断面面积得到保证,巷道成形能够满足使用需求。

     

    Abstract: To solve the problems of high stress, large deformation, and difficult control in the entry with extremely narrow coal pillar in extra-thick top-coal caving conditions, the relationship between the support force of the extremely narrow coal pillar and the roof-cutting length and angle was analyzed, the stress distribution characteristics and deformation evolution laws of the roof and coal pillar under different roof-cutting schemes were comparatively analyzed, and a coordinated "cutting-support-grouting" control technology was proposed. The analysis results showed that after roof cutting and pressure relief were implemented in the gob-side entry in extra-thick top-coal caving conditions, the support force of the extremely narrow coal pillar gradually decreased with increasing roof-cutting length and inclination angle, and the decreasing extent gradually increased. Increasing the roof-cutting length and angle caused both the vertical stress at different heights from the floor and the positions of the vertical stress intersection points in the coal pillar to move toward the entry, which was conducive to the stability management and control of the coal pillar. Field application results showed that after the coordinated control technology was adopted, the maximum displacement of the entry with extremely narrow coal pillar was only 269.03 mm, the maximum displacements of the surrounding rock on the coal-pillar side and the solid-coal side were 220.18 mm and 195.36 mm, respectively, and the minimum displacement of the floor of the entry was 92.83 mm. The surrounding rock deformation was effectively controlled, the cross-sectional area was ensured, and the entry shape could meet the service requirements.

     

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