Control of water leakages during TBM excavation – An example from the Follo Line tunnel project

Experiences from the execution of the two 20 long Follo Line tunnels may pave the way for the importance of a good understanding of how the geological and hydrogeological conditions may affect the achievement of a watertight tunnel. Different mitigations implemented, both during and after excavation by double shield TBMs, have defined a lesson learned for the performance of future TBM tunnels in order to control water leakages.