Semi-analytical characterization and stability control of asymmetric roadway instability under repeated mining in closely-spaced seams with remnant coal pillars

The stability of roadway surrounding rock is an essential prerequisite for safe underground coal mining. To reveal the deformation and failure mechanism of roadways underlying residual coal pillars in shallow-buried close-spaced coal seams under the influence of repeated mining, this paper takes the Bulianta Coal Mine as the engineering background, and analyzes the mechanical response mechanism and failure characteristics of roadway surrounding rock under the coupling effect of concentrated stress from residual coal pillars and repeated mining disturbances. The study quantitatively reveals the inherent correlation between the maximum failure depth of the plastic zone and four key parameters, namely stress ratio, vertical load, roadway radius, and surrounding rock strength, and clarifies the functional mapping relationship between each influencing factor and the failure depth. It elucidates the asymmetric spatio-temporal evolution mechanism of the mining-induced stress field and plastic zone throughout the full service life cycle of the roadway, and identifies the core inducing factor of the asymmetric failure of surrounding rock. On this basis, a targeted reinforcement support scheme is proposed, and its effectiveness is verified through field application, which provides important theoretical support and engineering reference for the safe mining of shallow-buried close-spaced coal seams.