Stability Analysis of End Face in Close Coal Seam Group Under Repeated Mining

The poor stability of the end face roof has been a major problem restricting the safe and efficient mining of large mining height working face, which is more prominent in the mining of the close coal seams. In view of the problem of roof caving of end face under repeated mining in close coal seam group, the stability of end face under repeated mining was studied by means of indoor test and theoretical analysis and numerical simulation. The research results showed that due to the influence of repeated mining, rock body fissures of end face are more developed, the rock body strength becomes lower as well, and the roof of end face is more prone to instability at the same roof pressure; during the mining of 17# coal seam, two kinds of “arch” structure and one kind of “masonry beam” structure will be formed at the top of different layers above the stope, and there will be three different degrees of roof pressure phenomenon; under the repeated mining of the coal seam group, the roof pressure is not large, thus, the main controlling factor of roof instability of end face is the rock body strength. Under this condition, the prevention and controlling measures of the coal face spalling and end face roof caving are advanced reinforcement for the coal face and the end face roof.