Asymmetric large deformation in deep mining-damaged roadways: mechanism and collaborative control technology by means of destressing-bolting

The stability control of mining-damaged roadways remains a fundamental challenge in mining engineering. This study investigates a typical mining-damaged roadway, with its deformation and failure characteristics summarized through field measurements. Numerical simulations were employed to analyze the failure characteristics and stress distribution law within the surrounding rock. This approach revealed the distribution law of deviatoric stress and the rotation law of the principal stress axis, thereby clarifying the failure mechanism in the mining-damaged roadway. The results of the study indicate that lateral mining disturbances have the effect of deflecting the principal stress axis of the surrounding rock, altering regions of high deviatoric stress and creating an asymmetric stress environment. Consequently, traditional symmetrical support systems are inadequate for adapting to this non-uniform stress distribution, ultimately leading to roadway instability. To address this, shaped charge blasting is proposed for roof cutting to optimize the stress environment. The effectiveness of this destressing technique is greatly affected by the height and angle at which the roof is cut. Building on these findings, a collaborative control technology is proposed, integrating shaped charge blasting for roof cutting with an asymmetric support system using both long and short cable bolts. Field monitoring results demonstrate that this technique ensures long-term roadway stability.