ABSTRACT
The development of the Montreal metro Line 5 also known as Blue Line Extension toward the northeast are located between the existing Saint-Michel station and Anjou. It consists of 6-km long double track tunnel, five new stations and seven auxiliary structures. Most of tunnel length (5.5 km) will be excavated by a 9.6 m diameter shielded rock TBM and supported by a precast segmental tunnel lining system. Based on the project master schedule, the five stations will be built first and then the TBM will skid through the already built stations. For the inter-station tunnels, the shielded rock TBM excavation method with segmental liner installation was selected based on the existing geotechnical challenges, evaluation of the project construction cost, schedule and risk, noise, and vibration. TBM will be fitted for probing and pre-excavation grouting to control water inflow into the tunnel during the excavation in fractured limestone and shale formation under the downtown of Montreal where lower rock quality and high water infiltration rates are anticipated. The latest development in segmental liner technology and the latest segmental liner design code ACI 533.5-20 were used for the design of the tunnel segmental liner of this project. The stations and auxiliary structures will be built using the controlled drill and blast method or roadheader. Two thin layers of shotcrete separated by a layer of spray-on membrane will be used as the initial and final liner of the underground stations and auxiliary structures resulting in significant construction cost and time savings. This paper presents major design aspects of the TBM tunnel and mined station caverns of this major project in Montreal, Canada.
