Abstract

The 7-mile long Flathead Tunnel in northwestern Montana was required in relocation of Great Northern Railway's main line track prior to impounding water by Libby Dam. Approximately 73% of the tunnel required structural steel tunnel sets for temporary support prior to the placement of concrete lining. A sliding floor, large special tunnel equipment, contractor initiated design changes to eliminate special trim and trench excavation, and laser survey alignment methods all contribute to a high speed excavation operation. Elimination of regularly spaced wall and arch contraction joints with waterstop through a value engineering proposal made a continuous lining operation possible. The conveyor placing system delivered concrete up to tunnel springline through form doors while the pump filled the tunnel arch.

Full Text
Published version (Free)

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call