浅埋近距煤层开采三场演化规律及煤柱群结构控制效应

Research on three-field evolution and control effect of pillars structural in shallow buried closely spaced multi-seams mining

  • 摘要: 为探索浅埋近距煤层开采煤柱减压与地表减损控制方法,以陕西省神南矿区柠条塔煤矿北翼东区1-2与2-2煤层开采为背景,采用物理模拟与理论分析相结合的方法,分析了浅埋近距煤层开采的应力场、位移场和裂隙场(三场)演化规律,建立了下煤柱集中应力、地表下沉、覆岩裂隙和地表裂缝发育与不同煤柱群结构的关系,提出了煤柱群结构的分类,揭示了煤柱群结构效应。研究表明,随上下煤柱错距增大,下煤柱最大垂直应力呈“大→小→大”变化,避开上煤柱集中应力传递区和上工作面采空区中部增压区,可实现下煤柱减压;不同错距煤柱结构形成的地表沉降分为沉降落差极值段、沉降落差减小段和沉降落差稳定段,在沉降落差稳定段地表裂缝最小。揭示了不同错距煤柱群结构对区段煤柱侧覆岩裂隙与地表裂缝的控制效应,确定了煤柱减压与地表减损的合理煤柱错距范围。基于三场演化规律,提出了煤柱群结构分类:叠置煤柱群结构、错置煤柱群结构、减压区分离煤柱群结构和压实区分离煤柱群结构;确定了“减压区分离煤柱群结构”可实现集中应力、地表不均匀沉降、覆岩裂隙和地表裂缝耦合控制,是最佳煤柱群结构。建立了基于煤柱集中应力控制的减压模型和基于覆岩位移与裂缝控制的减损模型,提出了煤柱减压与地表减损耦合控制方法,研究结果可为浅埋近距煤层安全减损开采提供依据。

     

    Abstract: In order to explore the control method of pillar pressure-reduction and surface damage-reduction in shallow buried closely spaced multi-seams mining, taking No.1-2 and No.2-2 seams mining in Ningtiaota coal mine in Shennan mining area as the background, combining with physical simulation and theoretical analysis, the three-field evolution in shallow buried closely spaced multi-seams mining is obtained, and the relationship between concentrated stress, surface subsidence, mining fractures and different pillars structural is revealed.The classification of pillars structural is proposed, and the pillars structural effect is revealed.The result shows that with the pillar malposition distance increases, the maximum vertical stress of lower pillar shows as “large-small-large”,avoiding the transfer concentrated stress by upper pillar, and also the high pressure zone of upper middle goaf, it is beneficial to pillar pressure-reduction.The surface subsidence fall stages based on coal pillar malposition distance and pillars structural are determined, including subsidence fall maximum stage, subsidence fall decreasing stage and subsidence fall stable stage, the surface fractures are the smallest in the subsidence fall stable stage.The control mechanism of coal pillar malposition distance and pillars structural to overburden and surface fractures is revealed, and the reasonable pillar malposition distance range is determined.Based on three-field evolution, the classification of pillars structure is proposed, it contains superposition pillars structure, staggered pillars structure, separate multi-pillars structure in pressure-reducing zone and in compacted zone, and the pillars structural effect is revealed.When the upper and lower pillars form “separate multi-pillars structure in pressure-reducing zone”,the concentrated stress, surface uneven subsidence and the concentrated fractures can be controlled effectively, and it is the best pillars structure.The pressure-reducing model is established based on the control of pillar concentrated stress, the damage-reducing model is established based on the control of overburden displacement and fracture, and the reasonable pillar malposition distance determination method is put forward to realize a coupling control of pillar pressure-reduction and surface damage-reduction, the research results can provide basis for safe and damage-reduction mining in shallow buried closely spaced multi-seams.

     

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