Study on ground pressure behavior law of fully-mechanized top-coal caving mining in shallow buried two-way inclined working face

Through the analysis of the geological conditions of the extra thick coal seam working face in Huangyuchuan Coal Mine of Shenhua Yili Energy Co.,Ltd.,it is found that there are structural uplifts in the middle of the five working faces in No.216 mining area,resulting in different degrees of working face direction and inclination.The inclination angle is formed to form a two-way inclined fully mechanized caving face,especially in the mining process of 216 upper No.1 working face,it is faced with the conditions of large slope mining,which has an impact on the equipment stability of the fully-mechanized top-coal caving face,and also brings challenges to top-coal caving and stope pressure control.In order to solve the problem of strengthening support management in fully-mechanized top-coal caving mining of two-way inclined working face in Huangyuchuan Coal Mine,FLAC3D software was used to simulate and analyze the mine pressure behavior law of two-way inclined working face in Huangyuchuan Coal Mine,and based on the numerical simulation results,the control measures for the working face were put forward.The research results show that:during the mining process of near-horizontal fully-mechanized top-coal caving face,the distribution of vertical stress,vertical displacement and plastic zone around the stope are symmetrically distributed in the inclined direction,and fluctuate regularly in the strike direction,while the distribution of two-way inclined fully-mechanized top-coal caving face is unevenly distributed and varies irregularly.Therefore,it can be judged that the mining of two-way inclined fully-mechanized top-coal caving face is likely to cause concentration of deviatoric stress on the roof,and the mine pressure behavior of the mining roadway at the low level position will be more severe,and it is necessary to strengthen the support and management.By simulating the flow law and caving situation of top coal in the process of top coal mining by PFC2D software,the flow and release law of top coal is studied.It is found that the top-coal recovery rate basically presents a gradual decreasing trend with the increase of dip angle.Therefore,in the field production,the coal caving process of fully-mechanized top-coal caving with large dip angle should be optimized.At the same time,the top-coal recovery rate and top-coal discharge rule under different coal caving processes are studied.The simulation results show that the recovery rate of top-coal is high under the condition of two or three rounds of sequential caving,indicating that multiple rounds of caving can make the top-coal sink slowly and evenly and minimize the mixing of roof gangue.According to the simulation results and field operability,it is finally determined that the coal caving method of Huangyuchuan mine is one cutting one caving and two rounds of sequential caving.