Simplified Method for Predicting Time-Dependent Behavior of Deep-Buried Tunnel Considering Tunnel Excavation Rate and Stress Release Effects

The excavation of a tunnel in soft rock will cause stress disturbance to the surrounding rock. Meanwhile, the creep of soft rock occurs under deviatoric stress, which may cause damage to the tunnel structure and affect its long-term service life. It is a challenge to evaluate the time-dependent behavior of deep-buried tunnels in rheological rock mass accurately and take measures to reduce tunnel convergence as much as possible for geotechnical engineers. A simplified method for calculating the stresses and displacements of the surrounding rock and tunnel lining with time is proposed in this paper. Moreover, theoretical derivations for four viscoelastic models are carried out based on the degeneration relationship between them. The effects of both tunnel excavation rate and rock stress release are considered. The analytical expressions of the lined tunnel are derived via the Boltzmann superposition principle and the theory of the integral equations. The effectiveness of the proposed analytical method is verified by the existing analytical solutions and the numerical simulation. Additionally, the calculated results are compared with those without considering stress release. Finally, parametric analysis is performed to investigate the influence on the responses of the deep-buried tunnel.