ABSTRACT
The 32.9 km long Koralmtunnel represents the key element of the new 130 km long railway line between Graz and Klagenfurt (Austria). The main lot KAT2, on Styrian side, includes a total of 4.5 km of main tunnel sections, 1 emergency-stop and 38 cross passages excavated by conventional methods, as well as 2x17 km of main tunnel excavated with two Double-Shield TBM (diameter approx. 10.0 m). The mechanized tunneling, in crystalline hard rock and with overburden up to 1’210 m, was successful and has overcome the pitfalls and difficulties of several fault zones of decametric extension. With the present contribution the authors intend to share the important goals achieved and the lessons learned.
