Technical research on surrounding rock control of roadways crossing collapse columns in strong mine pressure working faces

When roadways in strong mine pressure working faces traverse collapse columns, the complex stress redistribution frequently induces surrounding rock instability and support structure failure. This study investigates the 2702 intake airway crossing the X26 collapse column (75.8 m wide) at Zhangcun Coal Mine through an integrated approach combining theoretical analysis, numerical modeling, and field validation. Using elastoplastic mechanics theory and advanced numerical simulations (Midas GTS NX for 3D modeling and FLAC3D for stress analysis), we characterized the mechanical behavior of the collapse column structure zone, identifying distinct stress regions: a low-stress core zone (< 1 MPa), severe stress reduction zone (5 m radius), stress concentration zone (10 m radius, peak stress 15 MPa), and original rock zone. Theoretical calculations determined a plastic failure range of 50.01 m, informing the design of key engineering parameters: (1) optimized shallow-hole loose blasting with 0.5 m spacing, 1.6 m depth, and 0.6 kg charge per hole, creating effective pressure-relief zones; and (2) a 124.04 m strengthened support range. Numerical simulations demonstrated that the proposed "shallow-hole blasting + bolt-cable-mesh + π-steel shed" composite support system reduces plastic zone extent by 18% (from 195 to 160 mm), decreases roof subsidence by 6.6%, and limits sidewall deformation to < 200 mm. Field monitoring confirmed the system's effectiveness, maintaining roof displacement within 150 mm and ensuring structural integrity during the 75.8 m crossing. These results provide quantitative guidelines for roadway support design in collapse column areas under high mining-induced stresses.