Research On Surface Subsidence Thired Mining Section Of Ting Nan Coal Mine

Tingnan coal mine of Binchang Mining Area is located in the southeast Loess Plateau of East Gansu Province.It is part of the southern gully region of the loess plateau in northern shaanxi.There are hard sandstone of Luohe formation,whose thickness reached 200 m universally found in the mining coal seam overburden,occurrenced in the overburden strata of the thired panal of coal seam 4.The law of surface movement is co-coupled by the sandstone and loess layers of the Luohe Formation.It is of far-reaching practical significance to study the law of surface movement and deformation for the safe mining,in such special geological and mining conditions,under the building or structure of Tingnan coal mine and even the Bingchang mining area.Based on the research of No.4 coal seam mining in Sanpan District of Tingnan Coal Mine,this paper analyzes the characteristics of geological mining conditions in Sanpan District and observes the movement deformation on the surface of the mining face.The results show that when a single working face is mined,The surf-ace movement deformation is weak,the subsidence coefficient is only 0.028,and it does not cause damage to the surface building.It is not fully mining.When the mining is replaced by two working faces,the surface movement deforarmation amplitude increases,and the sinking rate reaches 0.15.Not fully mobilized.The working range of one working face and the mining face under two working face mining conditions is basically the same,but the sinking value and sinking speed of the surface point after mining of multiple working faces increase sharply,which is mainly due to the hardening of the Luohe Formation.Rock formation control.Th,e FLAC3D software was used to simulate the surface movement and deformation law of each working face.The results confirmed that the surface movement law of 303 and 305 working faces is basically consistent with the measured results.After the 307 working face is mined,the surface subsidence coefficient is 0.431,and the surface still has not reached full mining.After the mining of the 309 working face,the surface subsidence coefficient is 0.554,which is fully activated.Due to the control of the huge Houhe Formation sandstone,the mining range of the three-plate area to full mining is much larger than that under conventional mining conditions.When the ratio of the mining area to the mining depth is greater than or equal to 1.5.On the basis of surface measurement and numerical simulation,the movement deformation law and characteristics of the surface under the sandstone of the Luohe Formation in the Juhou Formation are further analyzed.In the Houluohe Formation sandstone,high-hard rock formations exist as the main key layer of the overlying strata,which is controlled by the control,so that the surface subsidence value is consistent with the deflection of the main key layer.Under this condition,whether the surface has reached full mining should be judged according to whether the maximum subsidence of the surface is consistent with the maximum deflection of the main key layer of the Luohe Formation sandstone.The research results lay a foundation for the research on the surface movement and deformation law of deep mining deep coal seam under the thick sandstone cover of Binchang mining area,which can be used as the reference basis for safe coal mining under the construction of the Changchang mining area.