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硬厚覆岩的破断与结构将发生显著的变化。针对汝箕沟煤矿二2煤层上覆厚层石英砂岩条件,采用现场实测、数值模拟、理论分析及现场试验等方法,研究了硬厚覆岩裂隙发育特征、破断运动、矿压显现特征及断顶控制技术,为硬厚覆岩工作面灾害防治提供了依据。研究表明,硬厚石英砂岩的微观结构致密完整,呈现大面积悬空、大步距破断运动,引起强烈的支架动载,甚至导致工作面风流逆转、沟通上部采空区隐形火区;硬厚岩层破断运移后产生明显的离层空间,并在开切眼上部和工作面上部及采空区中部形成覆岩主裂隙带,且发育高度大于经验计算数值,甚至与上方采空区沟通诱发灾害;实施开切眼深孔断顶爆破及降低工作面采高,有效缩短了硬厚岩层的初次破断步距,降低了支架动载及主裂隙带高度。
Breakthrough and structure of hard and overburden rocks will change significantly. Aiming at the condition of overlying thick quartz sandstone in No.22 coal seam of Rujigou coal mine, the development characteristics of fractures, breaking movement and mineral pressure of hard and thick overburden rock are studied by field measurement, numerical simulation, theoretical analysis and field test. Top control technology provides a basis for disaster prevention and control of hard and overburden rock face. The results show that the microstructure of hard and thick quartz sandstones is dense and complete, showing a large area of dangling and striding motion with large strides, which leads to strong dynamic loading of the stent and even leads to the reversal of air flow in the working face and the communication of the invisible fire zone in the upper gob; After breaking and migration, obvious detachment space was formed, and main strata of overburden strata were formed in the upper part of open cut and upper part of working face and in the middle of goaf, and the height of development was greater than empirically calculated values, even communicating with the upper goaf The implementation of open-cut deep-hole blasting and reducing the working face height effectively shorten the initial breaking step of the hard-rock formation and reduce the dynamic load of the support and the height of the main fracture zone.