The damage of tunnel surrounding rock masses usually results from the redistribution of stress in disturbed rock mass in tunnel excavation process. The excavation-disturbed zone (EDZ) is defined as the rock zone where the rock properties and conditions, such as fracture, stress and hydraulic aperture, have been changed due to the processes induced by excavation. EDZ is considered to be physically less stable and can form a continuous and highly permeable pathway of groundwater flow. The characterization of EDZ will affect tunnel support structure design, tunnel construction and tunnel surrounding rock mass stability analysis. Seismic survey techniques can be used to examine the nature of EDZ around the tunnel. Based on the concept of EDZ and the primary factors that lead to the change of rock properties, a methodology is proposed to depict mechanical and hydraulic behavior of EDZ. By using the in-situ data, deformability and hydraulic properties are studied by numerical analysis. The results show that the excavation damage depends on the excavation method. In addition, the influence boundary of the excavation-disturbed stress zone is smaller than that of the seepage. Therefore, the seepage boundary condition should be emphasized in establishing the coupled fluid-solid numerical models. The results will make the establishment of coupled fluid-solid model more reasonable.
Chinese Journal of Rock Mechanics and Engineering