Large Deformation Mechanism and Support Countermeasures of Deep-Buried Soft Rock Tunnels Under High Geostress State

To address the problem of large deformation in deep-buried high geostress soft rock tunnels, the Yuelongmen Tunnel was selected as the research subject and adopting the methods of on-site measurements, laboratory experiments and theories, the characteristics of large deformation and its mechanism in high geostress soft rock tunnels are studied in depth, and based on the mechanism of large deformation in tunnels and the concept of active and passive synergistic control, an optimized support scheme that dynamically adapts to the deformation of the surrounding rock is put forward. The results show that (1) the deformation volume and rate of tunnel surrounding rock is large, the duration is long, and the deformation damage is serious; (2) the main factors of tunnel surrounding rock deformation damage are high geostress and stratum lithology, followed by geological structure, groundwater and support scheme; (3) the tunnel deformation hierarchical control scheme effectively controls the deformation of surrounding rock, and reduces the deformation of steel arch and the risk of sprayed concrete cracking, which verifies the applicability of this scheme to the project. It verifies its engineering applicability. The research results provide important technical reference and theoretical support for the design and construction of similar projects.