Study on disaster caused by unbalanced spatial structure impact of overlying residual coal seam

In order to analyze the impact of the unbalanced space in the upper part of a mine of Shenxin Company on the impact hazard of the lower working face during the mining process，physical similar simulation experiments combined with on-site microseismic wave velocity inversion were used to draw the following rules：①the migration of the overburden in the working face all presents an inverted U-shaped distribution. When the lower working face approached to the unbalanced mining space at the upper part，the cracks develop obviously forward; ②when the lower working face is mined just below the upper coal cut，the overlying strata on the lower working face suddenly collapses，and the front of the working face is connected to the affected area of the unbalanced mining space，indicating that the most dangerous area is near the roadway cut in the upper unbalanced mining space; ③combining the similar simulations of the overlying spatial structure breaking activity characteristics and the microseismic energy distribution characteristics of the coal body stress evolution law obtained，it can be concluded that there is a strong impact risk and high impact hazard within the range of 0-80 m from the overlying unbalanced spatial structure area; ④analyzing the field microseismic wave velocity inversion，the lower working face starts at a distance of 200 m from the upper working face，and the stress concentration area gradually shifts from the W1123 lower channel to the upper channel until the stress concentration reaches the maximum at the opening of the upper unbalanced mining space. After cutting through the roadway，the stress is significantly reduced.