Abstract: This paper presents the Tunnel Boring Machine (TBM) selection results for the excavation of Daban long distance diversion tunnel. The double shielded TBM was selected for the specific site conditions: highly stressed soft rock mass, high external ground water pressures and expansive rock mass. The special construction techniques such as the remediation of sudden water, mud and sand rush into the tunnel, are also presented. The research results indicate that the TBM type selection is critical to the success of the long distance tunnels excavation. In addition to the cost, efficiency, and safety requirements, the site geological conditions should also be considered for the TBM type selection.

Key words: Double Shielded TBM, Diversion Tunnels, Open Excavation, Type Selections