ABSTRACT
The Principe-Caricamento-Grazie stretch of Genoa Underground System (twin tunnels, 1400 m long), currently under excavation with an EPB shield in heterogeneous ground (loose material, marlyclay and marly-limestone), under water table and very close to the seaside. Each single track tunnel has an excavation diameter of 6.10m and an internal diameter of 4.9 m. The tunnel overburden varies from 6m to 12 m, and the route heavily interferes with existing town buildings. According to the design work carried out by Rocksoil S.p.A., Milan, the tunnel lining consists of a first ring of pre-cast concrete segments and of a second cast lining. The two rings are separated by a waterproofing PVC membrane. Ground treatment by cement and chemical grout injections has been used to protect nearby building and Genoa Fly-over Road foundations. MPSP injection system and jet-grouting technologies have been used for these treatments on the sides and around the cavity. A large monitoring program has been applied to control tunneling in urban area.
