ABSTRACT
The Follo Line Project is one of the most important ongoing projects in Europe, connecting the Norwegian capital and the city of Ski with a high-speed railway. The main package consists in 2 tubes of 18.5 km each. The excavation has been carried out with 4 double shield TBMs. To backfill the gap between rock and concrete segments, the two-component system has been chosen and successfully used. Mapei worked with the contractor for the definition of the most cost-effective mix design, and the modification to the different conditions met during the tunnel excavation, have been some of the aspects of the successful application of the two component techniques. The paper describes the peculiarities of using two-component backfill grout in double shield TBMs, and the modifications to the mix design and to the injection procedure in conditions of relevant water inflow, one of the most challenging conditions for this technique.
