Abstract:In order to determine the optimal technical parameters of roof cutting and entry retaining with thick hard roof, the cutting heights of 5m, 10m and 15m and the cutting angles of 0°, 10°, 15° and 20° were selected. Through theoretical analysis and 3DEC numerical simulation, the shape of the roadway formed by the thick hard roof and the stability of the surrounding rock are studied. The results show that the roadway roof forms a “short arm beam” structure after roof cutting. When the roof cutting height and the roof cutting angle are constant, the greater the supporting force of the cut roof on the “short arm beam” of the roadway roof, the smaller the supporting force F required by the roof. Therefore, when cutting the roof into the roadway, try to make the cut roof fully connect to the roof; With the increase of the roof cutting height, the horizontal displacement value of the solid coal body side of the roadway increases and the vertical displacement decreases, while the horizontal displacement of the low roof of the roadway is almost zero; When the thick hard roof is cut into the roadway, it is necessary to maintain the inclined cutting seam. With the increase of the roof cutting angle, the vertical displacement of the roadway roof and the horizontal displacement of the solid coal body side increase. Based on this, the optimal roof cutting parameters with a roof cutting height of 10m and a roof cutting angle of 10° to 15° were comprehensively determined.
