煤矿水体下综放开采覆岩破坏规律研究OA

In order to meet the needs of safe mining and water disaster prevention and control of coal seams in Ningxia,this study reveals the development law of three zones of overlying strata in fully mechanized caving mining through multi-method fusion.Based on the engineering example of Wangwa Coal Mine,the elastic mechanical stress calculation model and FLAC3D numerical model are established.Combined with the field measured data,the dynamic failure mechanism of mining overburden rock is systematically analyzed.The results show that the failure of overlying strata in goaf presents the characteristics of sequential three-stage evolution.The height of caving zone is 52.5 m(caving/mining ratio is 6.0),the height of fracture zone is 127.6 m(fracture/mining ratio is 14.5),and the water-conducting fracture zone extends to 180.1 m(mining thickness is 20.5 times).Its development process is controlled by the effect of rock fragmentation and expansion and the dynamic evolution of stress arch.The numerical simulation shows that the vertical stress field forms an arch structure,the peak stress of the coal pillar in the working face is stable at 15～17 MPa,the maximum concentrated stress at the open-off cut reaches 18.2 MPa,and the stress of the 5#coal seam is reduced to 2.5 MPa due to the pressure relief effect.The study confirms that the mining-induced fractures do not penetrate the interlayer rock strata,and the maximum displacement of the surface bending subsidence zone reaches 5 300 mm.The water-resisting layer is formed between the 5#roof and the upper coal seam to effectively block the hydraulic connection.The results provide a theoretical basis for the optimization of multi-layer coal mining parameters and water disaster prevention and control.