Study on rational width of protective coal pillar for district dip in rock burst mine

The key to prevent rock burst in district dip is to reserve a protective coal pillar with a reasonable width.In order to discuss the determination method of protective coal pillar width in mining area of rock burst mine,determining reasonable width of protective coal pillar for district dip in Lilou Mine is taken as an engineering background.Movement law of overlying strata,evolution feature of abutment pressure and mechanism of rock burst in the advancing process of working face to the district dip are investigated by using ground pressure theory.The microseismic monitoring data and stress dynamic monitoring data in the process of working face advancing are analyzed.The influence range of working face in Lilou Mine is determined comprehensively.A comprehensive method to determine the width of protective coal pillar for district dip based on the principle of preventing all kinds of rock burst is put forward,and the engineering verification is carried out.The results show that:①With the working face advancing to the district dip and the lessening of protective coal pillar width,the advance abutment pressure of working face and the lateral abutment pressure of district dip,or the advanced abutment pressure of two wing working faces,will be superimposed and concentrated,and the superposition degree of vibration additional stress and lateral abutment pressure of district dip gradually increases.②Three types of rock burst may occur in the district dip,including static and dynamic load superposition type,stress superposition type and creep type.③The working face in Lilou Mine has a leading influence distance of 235 m,a lag influence distance of 235 m,a hysteresis influence distance of 235 m and a side influence distance of 105.5 m.④From the point of view of preventing three types of rock burst including static and dynamic load superposition type,stress superposition type and creep type,the width of protective coal 〖JP2〗pillar at one side for district dip in Lilou Mine should not be less than 235 m.The field monitoring results and ending situation in the late mining period preliminarily verified the rationality of 240 m protective coal pillar at one side of district dip in Lilou Mine.