Mechanism and control technology of roof cutting induced pressure relief in gob-side entry retaining with roadside backfill under thick coal seam conditions

To address the challenges of large deformation and stability control in filled gob-side entry retaining in thick coal seams, takeing the N3-13 working face as the engineering background. Integrated theoretical analysis, numerical simulation, and field experiments reveal the deformation characteristics and control challenges of surrounding rock in backfilled gob-side entries in thick coal seams. The structural evolution and pressure relief mechanism of “roof-cutting + filling” gob-side entry retaining in thick coal seams are clarified. A rational roof-cutting height formula is established, and the application effects of different cutting heights are evaluated. Results demonstrate that the key technical challenge lies in the rotational subsidence of the overhanging cantilever beam structure on the gob-side under dynamic overburden loading, directly inducing support system failure and large surrounding rock deformation. The synergistic control mechanism of “roof-cutting + filling” achieves efficient stress redistribution and relief on the goaf side by proactively severing the overhanging cantilever structure through directional pre-split roof cutting. Concurrently, the roadside filling body provides sustained support for the roof-cut short-wall beam structure, effectively suppressing surrounding rock deformation. Their synergy thus transforms the stress state of the surrounding rock from critical to stable. As the key parameter controlling entry stability, an increase in rational roof-cutting height drives the transformation of stress peak distribution in the solid coal rib from “single-peak” to “double-peak” , significantly reducing the stress level in the surrounding rock and shifting the stress concentration zone deeper into the coal-rock mass by 222.38% relative to baseline conditions. Field tests verified that increased pre-split roof-cutting height substantially reduces roadside filling load and surrounding rock deformation while synchronously shortening the impact cycle of overburden strata movement. The proposed synergistic mechanism of “roof-cutting + filling” and the rational roof-cutting height determination method provide a validated technical solution for controlling surrounding rock stability in gob-side entry retaining within thick coal seams.