Study on roof management measures of fully mechanized mining face passing through overlying room mining area

In the process of mining adjacent close coal seams, the coal pillars left behind after the mining of the upper coal seam are bound to form a high stress area, which will threaten the smooth mining of the lower coal seam.In view of the problems of strong ground pressure behavior and support crushing due to the influence of the residual concentrated coal pillar stress in the overlying short-range room mining area in the mining process of coal seam 22 in Liuta Coal Mine, this paper comprehensively uses the field measurement method, theoretical analysis method and numerical simulation method to study the causes of abnormal ground pressure and the law of ground pressure in the working face, puts forward the directional long borehole segmented hydraulic fracturing technology, and analyzes the implementation effect.The results show that the incoming pressure of the working face is very strong during the mining from the overlying concentrated coal pillar into the room goaf, the support subsidence of the working face is obvious, and the opening rate of the safety valve of the support pillar is high.After analysis, the main reason is the stress concentration of the overlying coal pillar, and the instability of the coal pillar under the influence of mining, resulting in multiple stress superposition.According to the numerical simulation results, when the overlying coal pillar is pushed out of the working face, the roof stress reaches the peak value, and the stress is gradually released after 5 m.By implementing hydraulic fracturing to release pressure in advance and weakening roof, the above problems of strong pressure can be effectively solved, so as to ensure the safety of mining operation and provide guidance for the safe production of subsequent working faces.