Research on stability analysis and control technology of roadways in the underlying isolated island working face

The mining of isolated working faces beneath close coal seams is influenced by the overlying goaf, the lateral abutment pressure from adjacent goafs, and the dynamic pressures arising from the preparatory mining operation. The deformation and failure characteristics of the surrounding rock in the roadway show significant variability, especially in sections beneath goaf areas and residual coal pillars, making it difficult to apply a conventional support strategy. This work adopts theoretical analysis, numerical simulations, and field observations to investigate roadway deformation and stability in the underlying isolated island working face according to the geological conditions of the Yanghuopan coal mine in Shaanxi province, China. The results indicate that the stress transfer from the residual pillar beneath the 2^-2 coal seam influences the 3^-1 coal seam up to a distance of 62.1 m, with a stress transfer coefficient of 1.6 directly beneath the coal pillar. The vertical stress in the 3^-1 coal seam is distributed across five distinct regions. The 30,119 working face traverses all five regions, with the vertical stress on the coal pillar and surrounding rock deformation reaching their maximum in the regions affected by the concentrated stress of the 1# and 2# residual coal pillars. Stress concentration is significantly reduced beneath the goaf of the 20,201 and 20,202 panels. Based on these findings, a corresponding stability control scheme was developed. The conventional support zone beneath the goafs and the original rock stress region of the 20,201 and 20,202 working faces, and the reinforced support zone within the influence of the residual coal pillars. Field observations, including surface displacement, anchor forces, and internal coal pillar deformation, validated the effectiveness of the combined support system and ensured safe production during isolated island working face mining.