Construction Stability Analysis of the Portal Section of Georgia's E60 Highway Tunnel Based on Numerical Analysis

Combined with the construction of the No. 6 tunnel of the Khevi-Ubisa-Shorapani- Argveta section of Georgia's E60 highway, the Midas GTSNX software was used to simulate the stability of the tunnel portal section during full-face construction. This paper analyzes the characteristics of displacement and stress variation of the tunnel portal slope during the whole section construction, the deformation law of surrounding rock during the whole section excavation, the deformation law of the initial support and final lining structure of the tunnel. The results based on the numerical simulation analysis show that when the entrance section of Georgia Tunnel No. 6 adopts full-face construction, the displacement of the supporting structure and the rock mass at the 5 m in front of the tunnel entrance changes greatly. Therefore, it is recommended to complete the invert construction of the tunnel before construction to ensure the safety of the tunnel entrance section; As for the entrance section as a whole, during the full-section construction process, the side slope of the entrance, the surrounding rock of the tunnel, and the supporting structure are all in a relatively stable state. Therefore, the full-section excavation of the No. 6 tunnel entrance section is safe and feasible.