Shallow tunnel construction using a new tunneling technique: M-CAM

摘要

Due to limitations with a conventional cut and cover method in urban areas and instability issuesrnand long construction duration with the New Austrian Tunneling Method, a new shallow tunneling technique,rnthe M-CAM, has been developed and applied to the Busan Subway Line No.1 Extension Project in South Korea.rnThe method includes installation of umbrella arch and additional steel arch supports to form a roof at the tunnelrncrown. Then, the roof is structurally integrated with a pre-installed CPW(Continuous PileWall) to transfer loadrnat the roof to the base ground. To verify structural stability and safety of the M-CAM, numerical analyses andrnreal-time monitoring have been conducted. The monitoring results showed 9mm ground settlement, 5.9mmrndisplacement at the tunnel crown and 0.7MPa stress of the shotcrete, corresponding to 45%, 26% and 37% ofrnthe analysis results, respectively. Furthermore, the method showed significant advantages in duration and costrnduring construction.