Relationship between overburden strata movement and strata behavior during dual system seam mining based on microseismic monitoring technology

With the dual system of coal mining in Datong mining area,the microseismic events space-time evolution characteristics under the influence of complex mined-out area at the upper Jurassic coal seam group during fully-mech- anized caving mining at the 8104 coal face in the Carboniferous extremely thick coal seam was investigated based on the high accuracy micro seismic monitoring technology. The relationship of strata movement and rock pressure under the influence of double series coal seams was obtained. The results show that the strata movement of the 8104 working face was enhanced when the 8104 face was close to the corresponding area under the upper Jurassic coal goaf. The coal mining working face in the Jurassic is the main reason for the increase of strata movement at the 8104 coal face. The distribution of seismic events was concentrated at the area with the Jurassic coal pillars overlap,the mining disturbance and the coal pillar overlap in the working face transferred stress,thus the vibration frequency with the total energy greater than 105 J was still high. Closing to goaf played a key role in the strata movement at the 8104 working face. Mi- croseismic events in advance at the 8104 coal face were concentrated under the joint action of the adjacent goaf and the Jurassic strata,and the mine pressure appeared sharp. The coupling effects of working face mining disturbance,ad- jacent goaf strata movement and the Jurassic overlapping coal pillar were the root cause of the mine pressure intensity at of the Carboniferous full-mechanized caving mining face.