Stability mechanism and control technology of large inclined working face roof in large-scale caving area

Based on the compound roof in the 211 112 working face of mine no. 2 in the Xinji area and various newly emerging geological conditions such as crack development in coal seams and major slopes, the roof of the severely sloped working face was studied focusing on the stress, strain and fracture features, along with the mechanism of rib spalling in the coal wall and the grouting strengthening technology. According to the analysis, the pre-loaded pressure on the working face tended to be redistributed with the development of the coal roof caving zone, which resulted in new stress concentration in the coal wall before the caving zone. Compared with the stress before rib spalling, stress decreased with the increased depth of rib spalling, which caused a slightly lower risk of rib spalling. Based on the analysis, an inorganic grouting reinforcement with a water-solid ratio of 3:1 was adopted to meet the needs of filling-body strength, which reduced operation time and increased economic benefits. The work ensures the safe and efficient mining of the composite roof face with a large inclination angle of Xinji No. 2 Mine and offers a reference for the mining coal seams under similar conditions.