Stability of surrounding rocks during reconstruction of abandoned mine roadways

Abandoned roadways have long-term creep behaviors in the high geostress environment. Under the dual effects of creep and reconstruction-induced dynamic disturbance, surrounding rocks exhibit poor stability. Under the engineering background of a roadway in a coal mine in Liaoning Province, China, the surrounding rock stability in the initial roadway excavation process and the long-term creep process of the abandoned roadway was evaluated based on numerical simulation. Results show that the displacement and deformation of surrounding rocks after the initial excavation of the abandoned roadway are dominated by vault subsidence. The mechanical properties of roadway surrounding rocks are gradually deteriorated in the abandonment time of four years. The deformation of surrounding rocks linearly enlarges with prolonging creep time, and the surrounding rocks are in the steady-state creep process on the whole. The better the lithology of surrounding rocks is, the smaller the damage zone with failure tendency in surrounding rocks after reconstruction of the abandoned roadway. With the increments of burial depth and creep time of the abandoned roadway, the area with failure tendency in surrounding rocks enlarges after reconstruction. Enlarging the expansion size appropriately in the range of the initial damage zone formed due to the long-term creep effect can effectively improve the quality and stability of surrounding rocks. The surrounding rock stability of abandoned roadways with circular, straight-wall-top-arch, and rectangular cross-sections decreases successively after reconstruction. The research results provide theoretical reference for the reconstruction of abandoned roadways and the stability analysis and evaluation of surrounding rocks in mines.