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针对晋城矿区开展下保护层开采试验,采用模拟试验,现场实测等手段研究下保护层开采覆岩运移、裂隙动态演化特征及被保护层变形规律。模拟结果表明:伴随基本顶的周期破断,采动裂隙呈梯形演化,贯通的竖向裂隙没有连通至上被保护层。保护层开采后,被保护层下沉平缓连续,膨胀变形率保持在0.5%左右。深基点位移计动态监测下保护层94302工作面开采覆岩运动全过程,得到了监测岩层的移动曲线,掌握了上覆岩层横向三区、纵向三带离层裂隙时空演化规律。通过钻孔电视观测覆岩裂隙分布特征及被保护层煤体结构变化,得到冒落带高度2.2~4.5 m,裂隙带高度20.0~25.7 m,发现被保护层煤体受采动影响产生水平方向为主的小角度次生裂隙。
Aiming at the exploitation test of lower protective layer in Jincheng mining area, this paper studied the characteristics of overlying rock migration, the dynamic evolution of fracture and the deformation of the protected layer by means of simulation test and field measurement. The simulation results show that with the rupture of the basic roof, the mining fractures evolve trapezoidally, and the vertical fractures that pass through are not connected to the upper protected layer. After the protective layer is mined, the protective layer sinks gently and continuously, and the expansion deformation rate remains at about 0.5%. Deep Base Point Displacement Monitor Dynamic monitoring of the entire process of overlying strata mining in the 94302 working face of the protective layer monitored the movement curve of the strata, and grasped the temporal and spatial evolution of the stratified fissures in the three lateral and vertical zones of the overlying strata. Through the observation of the distribution characteristics of the strata fissures and the change of the structure of the coal seam in the protected area through the borehole TV, the height of the fissure zone is 2.2-4.5 m and the height of the fissure zone is 20.0-25.7 m. It is found that the coal- Based on the small angle of secondary cracks.