Stability Assessment of Operation Tunnels Considering Long-Term Interaction Between the Lining and Surrounding Rock

Operational tunnels are generally accompanied by time-dependent deformation and structural failures due to delayed behaviors, e.g., loading effects from surrounding rock and degradation of the concrete lining. This paper presents an analytical approach to investigate the long-term stability of tunnels considering those delayed behaviors. To quantitatively characterize the degradation process of concrete lining, specific degradation models are adopted according to the identified obstacles in service environments. The viscoelastic Burgers model is selected to recognize the long-term creep properties of the surrounding rock. The time-varying solutions for tunnel deformation and lining stress can be obtained using the displacement compatibility condition between the concrete lining and the surrounding rock. The results find that the long-term stability of tunnels is governed by the interaction between the concrete lining and the surrounding rock. Different degradation models and rates significantly influence mechanical response, with thinner linings showing greater susceptibility. Viscoelastic rock properties further affect system behavior. The amplified effect of degradation under long-term rock loading underscores the necessity of understanding these coupled mechanisms for accurate life predictions. On account of the findings, a long-term performance maintenance method for operation tunnels is proposed and illustrated by a rehabilitation project for tunnel damage. Remediation of structural damage in operation tunnels should consider the surrounding rock condition and support structure performance, significantly improving long-term safety and reducing remediation costs. Overall, the present work provides some insight into the long-term stability assessment of operation tunnels.