Fracture development of overlying strata and optimization of high position boring: with working face 34low 2 in Qinan mine as example

In order to improve the gas extraction effect of high position boring effectively, this paper analyzed the overlying strata fracture development regularities and the change of separation rate during mining of 34_low2 working face in Qinan mine, judged the distribution range of caved zone and fractured zone in the coal seam overlying strata, determined that the best range of norm distance parameter of high position boring was 12~22 meters to 3₂ coal seam roofs, which provided a scientific basis for optimization of high position boring in other working faces.