Numerical Simulation Study on Through-Anchor Cable Reinforcement Control of Inter-Roadway Coal Pillars in Double-Roadway Layouts

This study investigates the traditional coal pillar support methods employed in double-roadway excavation of high-mining-height longwall faces, specifically those with widths ranging from 20 m to 30 m. It highlights that these methods not only result in substantial coal pillar loss and low recovery rates but also create conditions for stress concentration due to inadequate dimensions, thereby increasing the risk of accidents. Based on the engineering context of the Jinjitan Coal Mine’s 113 and 111 working faces, this paper optimizes coal pillar dimensions through theoretical calculations and Flac3D numerical simulations, with the results indicating that the optimal coal pillar width is 12 m. Analysis of a 12 m inter-roadway coal pillar focuses on the bearing characteristics of auxiliary transport roadways and coal transportation roadways. Five different reinforcement schemes are examined, including (no support, conventional anchor reinforcement, presser anchor cable through reinforcement, constant-resistance large-deformation anchor cable through reinforcement, and a combination of presser with negative Poisson’s ratio (NPR) constant-resistance large-deformation anchor cable support). The findings reveal that in the investigation of the reinforcement mechanism for the 12 m wide coal pillar, employing NPR constant-resistance large-deformation anchor cables alongside presser anchor cables effectively mitigates the compression deformation caused by dynamic loading disturbances from the overlying rock layers. This approach not only dissipates energy but also transforms the coal pillar from a biaxial stress state to a triaxial stress state. The reinforcement scheme successfully reduces the peak stress of the coal pillar from 68.5 MPa to 35.3 MPa, significantly enhancing both the peak strength and residual strength of the coal pillar, thereby ensuring the stability of the inter-roadway coal pillar and the safe recovery of the working face.