Research on large deformation mechanism of recovery roadway under mining stress conditions.

Single Recovery Roadway (SRR) is a novel retraction technology in the non-pillars mining innovation system. In previous support withdrawing, single recovery roadway was usually replaced by a dual-recovery roadway or cut the coal wall before the support. This study is set against the background of the longwall panel at Duanshi Coal Mine, where a mechanical model based on the stress characteristics of a composite cantilever beam was constructed to analyze the failure of the main roof in a single recovery roadway. Through numerical analysis, the relationship between deformation failure of the recovery roadway and interlayer slippage structures was explored, as well as how mining-induced stress distribution and the evolution of key strata fractures impact the stability of the roadway. The results indicate that after the connection of the longwall panel and the recovery roadway, the overlying composite interlayered rock strata are affected by the interlayer slippage structures, leading to significant asymmetric deformation in the surrounding rocks. Additionally, borehole observation data support the theoretical calculations of the cantilever beam model. These research results enhance the understanding of the interlayer slip instability mechanism and provide important guidance for mine design under similar geological conditions.