ABSTRACT

The construction of the new high-speed freight railway line between Milan and Genoa, the “Terzo Valico dei Giovi”, required the excavation of 4 adits which will provide access to the excavation faces during the construction phase as well as to the railway line for maintenance and safety purposes during the operation phase. The Polcevera adit has been realized by an EPB TBM named “Giulia”. However, the TBM got stuck after driving about 1.300 m inside the tunnel, although capable to deliver a maximum thrust force of 88.000 kN (in normal conditions the applied thrust force is equal to 20.000 kN). Soon after the TBM getting stuck, a number of measures were carried out in order to increase the TBM’s thrust force and at the same time to decrease friction between the rock mass and the TBM’s shield and tail.