Mechanism and control of asymmetric deformation of surrounding rock in gob‐side roadway driving along narrow coal pillar in extra-thick coal seam

• Developed a mechanical model of overburden key blocks above gob-side entries with narrow coal pillars, identifying failure patterns and dimensional characteristics of lateral key blocks. • Analyzed roof bending moment and deflection distributions in gob-side entries, revealing the fundamental cause of asymmetric large deformation and failure. • Conducted numerical simulations of stress and displacement fields during roadway excavation, clarifying asymmetric roof failure distribution and spatial characteristics of severe deformation types. This study focuses on the asymmetric large deformation of surrounding rock during gob‐side roadway driving along narrow coal pillars in extra-thick coal seams. Taking the 5230 return airway of the 8230 working face in Tashan Mine as the engineering background, a structural mechanical model of the overburden was established to calculate the fracture characteristics and specific location of key blocks above the roadway. A roof beam model was further developed to analyze the distribution of bending moment and deflection, while FLAC3D simulations were employed to investigate the distribution characteristics of the deviatoric stress field and displacement field. The results show that: (1) The key block fractured approximately 15.92 m into the coal wall, controlled by seam thickness, immediate and main roof thickness, mining parameters, and periodic weighting; (2) The roof beam bending moment and deflection exhibited pronounced asymmetry, with values on the pillar side exceeding those on the solid-coal side, which directly causing roof asymmetric deformation; (3) Shallow surrounding rock experienced severe damage, with tensile deformation dominating on the coal pillar side, while the solid coal side showed higher distortion energy and more complex strain types. Based on these findings, an asymmetric anchor bolt-cable combined with truss anchor cable support system was proposed and field application verified its effectiveness in controlling asymmetric deformation.