High-Speed Railway Milan – Genoa, implementation of coupled analysis to estimate thermo-mechanical effects produced by the fire on the TBM segmental lining
The Stretch of the Italian High Speed Railway between Genoa and Milano is currently under construction with more than 78 km running tunnels and will be completed by 2021. More than 20 km of the tunnel excavation will be executed by EPB TBM, with overburden ranging from 5 to 600 m and geomechanical condition varying from hard rock to soft marble. Segmental lining, in precast concrete and polymeric fibers, is characterized by outer diameter of 10 m and thickness of 40 cm. The paper describes the implementation, by FLAC thermal code, of coupled analysis to estimate thermo-mechanical effects produced by fire on TBM segmental lining cross section, applying on the intrados the EUREKA (2008/163/CE) and the RWS (UNI 11076) fire curves, for 120 minutes. Analysis starts from stress-strain conditions at the end of tunnel excavation and permits to model thermal damage and degradation of concrete, with progressive increase of temperature, in accordance with Eurocode 2. The analysis of fire effects on exposed segmental lining are carried out by combining the thermal actions with the rock mass pressure around the excavation, taking into account the presence of segmental joints during thermal analysis.