ABSTRACT
The 7,548 m long and 15.965 m wide Santa Lucia tunnel, close to and north of Florence (Italy), is in execution by means of a TBM-EPB with high overburden and water head, and methane is presence. The tunnel crosses a highly tectonized shale complex and a limestone formation set in a series of tight anticlines and synclines. In the design phase, the GSI index was defined for the entire tunnel length; lab tests allowed determining USC and drillability. On this basis, during the design stage the ARAT (theoretical Average Rate of Advance, m/d) was computed according to additional methods, such as for instance RME (Rock Mass Excavability) and FPI (Field Penetration Index, kN/cutter/mm/rev). The calculated ARAT ranges, according to the methods and the tunnel chainage, is around 15 m/d. This figure is compared to the real excavation ARAT and matched to the TBM data related to the employed energy in excavation.
