Study on the deformation behavior and control technology of roadways under the influence of front abutment pressure

As coal resources become increasingly scarce, it is crucial to minimize the distance between the mining stop line and the main roadways to optimize coal recovery rates. However, the front abutment pressure will significantly affect the stability of the main roadways. This study conducted physical model tests and numerical simulations, demonstrating that the reduction of the coal pillar influences the increase in abutment stress in two stages. During the initial stage, the abutment stress within the coal pillar increased gradually, whereas the rate of increase in the subsequent stage was significantly accelerated. If the pillar width decreased below the threshold value (55 m in this study) between the two stages, the peak of the abutment stress would shift towards the main roadway, thereby accelerating the deformation and failure of the roadway. As the front abutment pressure increased, the deformation of the main roadway was primarily characterized by rib-to-rib convergence. The failure mode of the surrounding rock involved floor heave, asymmetric failure of ribs, and roof subsidence, resulting in the drastic instability of the surrounding rock. A new stress-control protecting roadway technology has been proposed, which simultaneously facilitates pressure relief through the special roadway and pressure control through pre-grouting reinforcement. Field application results indicated that this technology can effectively mitigate the stressful environment around the main roadway, thereby ensuring its stability and safe operation.