Unified Elasto-Plastic Solution for High-Speed Railway Tunnel in Cold Regions Considering Dual Transverse Isotropic Model of Frozen Rock Mass

Frost damage is one of the main influencing factors for the deterioration of support structures in cold-region tunnels. A new dual transverse isotropic model of frozen rock mass is first proposed based on parameter strain and elastic modulus to serve as the theoretical basis for tunnel operation safety in cold regions. Subsequently, a unified elasto-plastic solution for high-speed railway tunnels in cold regions is derived based on the new dual transverse isotropic model, and the accuracy of the analytical solution is verified by comparisons with existing models and experimental results. Finally, the effect of the model parameters on stress and displacement is explored. The results reveal a significant negative correlation between the plastic radius of the frozen rock mass zone and the pressure acting on the inner surface of the support structure, the influence coefficient of intermediate principal stress, radial-gradient influence coefficient of the frozen rock mass, and anisotropic frost heave coefficient of the frozen rock mass, as well as between the frost-heaving force and the influence coefficient of intermediate principal stress parameter. However, the frost-heaving force is positively correlated with the pressure acting on the inner surface of the support structure, the radial gradient influence coefficient of the frozen rock mass, and the anisotropic frost heave coefficients of the frozen rock mass. Therefore, the pressure acting on the inner surface of the support structure, the radial gradient influence co-efficient of the frozen rock mass, and the anisotropic frost heave coefficients of frozen rock mass should be reasonably considered, but the strength theory of the surrounding rock should be strongly considered in the design of tunnel structures in cold regions.