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为了掌握非充分稳定覆岩下综放沿空掘巷窄煤柱变形机理,采用矿用钻孔窥视仪对非充分稳定覆岩下综放沿空掘巷窄煤柱进行了钻孔摄像观测,提出了“基本测量尺度-破碎等级逐级评判”钻孔裂隙统计方法,研究分析了裂隙分布规律。研究表明:1)非充分稳定覆岩条件下综放沿空掘巷窄煤柱裂隙多以径向裂隙及离层形式存在,异常破碎带主要出现在煤柱两端,煤柱中部多存在间隔分布的径向裂隙,微小裂隙几乎全部存在于煤柱中部。2)按照破碎程度的不同,窄煤柱可分为3个区域,即近巷破碎区A、中部稳定区B和沿空破碎区C。B区更靠近C区,整体区域分布表现出几何上的不对称性。3)控制该类煤柱变形的基本思路是控制基本顶断裂后关键块的回转和滑移,提出了“控回转、重锚固、强限制”内外联合控制方法。
In order to grasp the deformation mechanism of narrow coal pillar along gob-side entry in fully mechanized top-coal caving face under incomplete and stable overburden, borehole camera observation was carried out by using mine borehole peephole on narrow coal pillar of gob-side entry under fully mechanized overburden with insufficient stability “Basic measurement scale - step by step evaluation of crushing ” statistical method of fractures of boreholes, study on the distribution of fractures. The results show that: 1) The fractures of narrow coal pillar in gob-side entry caving of gob-side entry caving in fully mechanized top coal caving face mostly exist in the form of radial fissure and delamination under the condition of inadequate and overburden strata. The anomalous fractured zone mainly appears at both ends of coal pillar, Distribution of radial cracks, tiny cracks almost entirely in the middle of coal pillar. 2) According to the degree of fragmentation, the narrow coal pillar can be divided into three areas, ie, the near-alley crushing zone A, the central stability zone B and the crushed zone C along the sky. Area B is closer to area C, and the overall area distribution shows geometrical asymmetry. 3) The basic idea of controlling the deformation of such pillars is to control the rotation and slippage of the key block after the basic roof fracture, and a combined control method of “control slewing, heavy anchoring and strong restraint” is proposed.