Permeability and pressure distribution characteristics of the roadway surrounding rock in the damaged zone of an excavation

Research on the permeability and pressure distribution characteristics of the roadway surrounding rock in the excavation damaged zone (EDZ) is beneficial for the development of gas control technology. In this study, analytical solutions of stress and strain of the roadway surrounding rock were obtained, in which the creep deformation and strain softening were considered. Using the MTS815 rock mechanics testing system and a gas permeability testing system, permeability tests were conducted in the complete stress-strain process, and the evolution characteristics of permeability and strain were studied over the whole loading process. Based on the analytical solutions of stress and strain and the governing equation of gas seepage flow, this paper proposes a hydro-mechanical (HM) model, which considers three different zones around the roadway. Then the gas flow process in the roadway surrounding rock in three different zones was simulated according to the engineering geological conditions, thus obtaining the permeability and pressure distribution characteristics of the roadway surrounding rock in three different zones. These results show that the surrounding rock around the roadway can be divided into four regions-the full flow zone (FFZ), flow-shielding zone (FSZ), transitive flow zone (TFZ), and in-situ rock flow zone (IRFZ). These results could provide theoretical guidance for the improvement of gas extraction and gas control technology.