厚煤层大采高坚硬顶板巷道大变形控制方法

Large deformation control methods for roadways in thick coal seams with high mining height and hard roof

  • 摘要: 针对厚煤层大采高坚硬顶板围岩控制,传统留煤柱的巷道布置方式会引起巷道强矿压显现,导致巷道围岩大变形、冲击地压等破坏性问题。基于开挖理论,介绍了对应的开挖补偿理论,构建了切顶卸压与高预应力吸能相耦合的支护体系:通过定向预裂切缝切断巷道顶板与采空区顶板间的应力传递,减小巷道围岩积聚的弹性应变能;研发了NPR高预应力锚索,利用NPR高预应力锚索支护构件对巷道围岩进行控制,当煤岩体产生的荷载超过某一阈值时,支护构件通过变形吸收冲击能,削弱煤岩体积聚的能量。为满足切顶卸压无煤柱开采技术需求,提出了顶板定向切缝和矸石巷帮挡矸2项关键技术。现场工程试验结果表明,该技术卸压效果显著,切缝侧卸压比最高可达19.5%,显著减小了巷道围岩变形速率及变形量,最大围岩变形量仅为52 mm,取得了较好的围岩控制效果。

     

    Abstract: For the control of surrounding rock in thick coal seams with high mining heights and hard roofs, the traditional roadway layouts employing coal pillars often induce strong strata behavior, resulting in large deformations, rock bursts, and other destructive issues in surrounding rock. Based on excavation theory, an excavation compensation theory was introduced, and a support system coupling roof-cutting pressure relief with high pre-stressed energy absorption was constructed. Directional pre-splitting fractures were introduced to sever stress transmission between the roadway roof and goaf roof, thereby reducing accumulated elastic strain energy in the surrounding rock. NPR (Negative Poisson's Ratio) high prestressed anchor cables were developed to control surrounding rock deformation. When the load generated by the coal-rock mass exceeded a critical threshold, the supporting components absorbed the impact energy through deformation, mitigating energy accumulation. To meet the technical requirements of non-pillar mining with roof-cutting for pressure relief, two key techniques, namely directional roof-cutting and gangue roadway side support, were proposed. Field tests demonstrated significant pressure relief effects, with the maximum pressure-relief ratio on the cutting side reaching up to 19.5%. The surrounding rock deformation rate and magnitude were significantly reduced, with the maximum deformation limited to 52 mm, confirming superior strata control performance.

     

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