Excavation-induced deformation and damage evolution of deep tunnels based on a realistic stress path

The stress path during underground excavation is critical to the mechanical response of rock masses, and the excavation effects in front of a tunnel face cannot be ignored. In this study, a realistic stress path model was built to capture the actual behaviour of the surrounding rock during the entire excavation process. The key technical steps of the two-dimensional excavation simulations with this method were presented. This approach was applied to characterise the deformation and damage evolution of an experimental tunnel, where the soft rock under high stress experienced severe damage. The research results revealed the evolution of the excavation-induced deformation and damage, which was in good agreement with the results of field investigations and previous research. The cause of support failure was found to be that the growth process of the excavation damage zone (EDZ) was different from the convergence displacement, and the evolution of the EDZ did not receive sufficient attention during the design of the support. Corresponding suggestions for the improvement of support designs were put forward. The proposed method could provide key information for predicting the long-term performance and determining a reasonable design for the support of tunnels exposed to a high risk of destruction.