Research on localized roof falling mechanism of bolt supporting roadway in large mining height working face

In view of the problem of coal mine safety production caused by roof fall in large mining height working face, the field measurement and numerical simulation method were used to study the influencing factors of localized roof collapse. Field tests show that the direct roof of the roadway at the location of roof fall is 5.8 m mudstone with multi-layer composite. There is a weak shale rock formation near the anchorage end of the anchor cable, accounting for 54.3% of clay minerals. Significant separation occurs in the anchorage zone of the anchor, and the support body is shear-deformed by the displacement of the rock stratum. The numerical simulation shows that the weak joint surface of the roof is separated, the integrity of the supporting stress field is lost, and the rood fall occurs after plastic failure due to the the factors such as mining under unstable dynamic pressure, small size of the pillar and insufficient support strength and stiffness. It is proposed to timely support in the geological anomaly area, increase the support strength to prevent the anchorage zone from separating, strengthen the construction quality inspection and other technical means, improve the safety factor of the roadway, which provides engineering references in order to reduce the roof accidents.