Abstract: This paper presents the numerical analysis and construction monitoring results of a sixlane double arch expressway tunnel. The surrounding rock mass deformation and the stress in the supporting structures are estimated by numerical analysis and verified throughout the construction monitoring. The results indicate that, during the tunnel excavation, the largest deformation and the highest stressed locations are at the top of median wall and the outer wall at both sides. As a results, special strengthening design is required at these locations. In soft soils, the median wall of the double arch tunnel might experience heaving and improvement measures are necessary.

Key words: Double-Arched Tunnel, Surrounding Rock Mass, Numerical Analysis, Construction Monitoring