Study on the surrounding rock stability of columnar gob-side entry retaining under the influence of repeated mining

This study takes the columnar gob-side entry retaining （C-GSER） technology at Wangzhuang Coal Mine as research context. By integrating the fracturing characteristics of the overlying rock during two mining cycles, a mechanical model of the roadway roof is constructed to analyze the stress transfer mechanism and stress state of the roof. Using FLAC^3D numerical simulation software, a computational model for columnar gob-side entry retaining is established to investigate the dynamic evolution and static distribution characteristics of mine pressure. The stability of the surrounding rock under repeated mining impacts is discussed from the perspective of shear stress distribution. Results indicate: overburden exhibited rotational and integral failure-subsidence patterns during the two mining cycles, with the roadway roof transitioning from “compression-bending” combined deformation to “compression-bending-torsion” combined deformation. The mining influence zone extends 20 m ahead of the coal face, where stress change rates progressively increase. Within the 30 m zone behind the coal face, the primary stage of stress redistribution occurs. Differential rock deformation generates inter-layer shear stresses, with stress concentration zones exhibiting phased migration and expansion characteristics. The rock mass control technology scheme employing “advance reinforcement support + integrated roadway side support + spatial isolation support” has effectively controlled rock mass deformation.