Method to Evaluate the Safety of Tunnels through Steeply Inclined Strata in Cold Regions Based on the Sidewall Frost Heave Model

AbstractIn this paper, safety evaluation for tunnels through steeply inclined strata in cold regions is proposed, for evaluating the safety of lining structures with existing or underlying frost heave damage. Laboratory model tests are performed to investigate the distribution characteristics of the frost heave force that acts on the lining structure, which plays an important role in the assessment of safety. The sidewall frost heave model is determined as the most fitting frost heave model in steeply inclined strata based on the available experimental data. The stress increments under frost heave can be obtained by applying the sidewall frost heave model to numerical simulations. Specifically, the maximum stress in the lining structure mainly includes two parts: the initial maximum stress under self-weight and the stress increment from the frost heave. The safety factor can be calculated through the ratio of the lining material’s strength to the maximum stress in a worst-case scenario. Finally, the practicality of the safety evaluation method is confirmed through an examination of the Balang Mountain tunnel in Southwest China.