Study on Deformation Characteristics of Surrounding Rock in Deep‐Buried Tunnels of Plateau Railroads

Regarding the deformation problem of surrounding rock in deep‐buried tunnels of high‐altitude railways, this article adopted a combination of numerical simulation and in situ monitoring analysis methods relying on a new plateau railroad tunnel. The deformation evolution law of tunnel surrounding rock under different burial depth conditions and its control technology were systematically studied. The study revealed the nonlinear growth characteristics of perimeter rock deformation with depth of burial. The mathematical fitting equations for arch crown settlement, arch base uplift, and convergence of arch shoulders and waists were established. Comprehensive control technology based on micro‐step excavation, high‐performance support system, and automatic perimeter rock deformation monitoring system (train control and monitoring system [TCMS]) was proposed. The results demonstrate that: the final deformation of the surrounding rock increased exponentially or power function with increasing burial depth. The rate of deformation increased significantly after the burial depth exceeded 1000 m. The critical transition of the surrounding rock from an elastic to a plastic state was revealed; sensitivity analysis of the support structure illustrated that: lining type > anchor spacing > anchor length > length of overrun pipe roof. The TCMS verified the reliability of the numerical model. The research results can provide theoretical basis and technical support for the safe construction of plateau deep‐buried tunnels.