Swelling deformation law of roadway roof on extra-thick isolated island working face

Under the conditions of extra-thick coal seam mining, the swelling deformation of the roof in isolated island working face roadways poses significant challenges to advanced support and rockburst prevention. This study takes the 13312 isolated island working face of Sunjiagou Coal Mine as the research object, successfully obtained coal (rock) cores and conducted physical and mechanical parameter tests. Based on the determination results of mechanical parameters, the key strata in the overlying rock were identified. The identification results show that the overlying rock of the 13312 isolated island working face contains 1 main key stratum and 5 sub-key strata. By merging the soft rock controlled by the key strata, a numerical calculation model was established using COMSOL software. The simulation results indicate that the roof swelling at the coal wall of the isolated island working face is the largest, with the severe expansion zone extending within 40–50 meters ahead of the working face. Beyond 50 meters ahead of the working face, the roof expansion rapidly decreases. The greater the mining height and the deeper the burial depth, the larger the roof swelling deformation in the roadway of the mining working face. when the mining height is 14 m and the mining depth is 450 m, the roadway roof swelling deformation reaches 205.1 mm, with a severe expansion zone spanning 50 m.