Deformation mechanism and support technology of deep asymmetrical soft rock roadway

The support technology for roadway rock has always posed significant challenges in mining and tunnel engineering. This is particularly true for deep asymmetrical soft rock roadway, for which no effective and mature reference technology currently exists. This paper provides a comprehensive analysis of the deformation mechanism and support technology for deep soft rock roadway at the Qingyun mine. Based on field investigation and theoretical analysis, we summarize the deformation mechanism and its influencing factors. Numerical simulation results of excavation indicate that the improved support scheme effectively controls roadway deformation, with 68.0 mm for the roof, 26.3 mm for the floor, and 45.12 and 44.98 mm for the two sidewalls. Moreover, the plastic zone depth is significantly reduced by 0.5 m to 2.0 m of roadway. Field monitoring data, including peephole, acoustic velocity, and bolt stress measurement, strongly support the positive impact of the improved support on surrounding rock deformation and stability. As the working face advances, the influence of mining disturbance on the roadway increases. Compared to primary support, the deformation of improved support scheme reduces by 17 to 65 mm. The outline of the loose circle under the improved support scheme is mapped, showing an overall depth reduction of 0.58 and 0.20 m compared to conditions without support and with primary support, respectively. We hope this research serves as a valuable reference for other soft rock engineering projects.