ABSTRACT
The raising water table in the Milan area affects some of the Metro lines constructed in the past without waterproofing. The problem should be faced by acting on the Metro lines in operation before water inflow could compromise the regular Metro service. The paper describes the two phases intervention studied for subway line M2 between the Piola and Lambrate stations. The first phase, was aimed at stopping water inflow and to repairing the invert strongly compromised. The second phase concerns water tightness and long-term stability of tunnel, through the creation of a shell of consolidated ground. Grouting operations will be executed both from inside the tunnel and from the surface, the last one requiring particular attention for the protection of the tunnel lining. Consequently a dedicated real-time monitoring system has been studied to avoid any damages to the lining in order to guarantee the metro service in safety.
