Gebirgsdruckabhängige Tübbing‐Öffnungsvarianten für Querschläge beim Koralmtunnel KAT3 – Entwicklung von Sicherungstypen zum Einfahren von Querschlagvortrieben in Tübbingröhre

Abstract The southern tube of the Koralm Tunnel, contract KAT3, is being conventionally excavated with two‐pass lining, while the northern tube is being driven by TBM with single‐pass segment lining. The tunnel tubes are located in quite different geotechnical conditions, with soft ground of high and low permeability, major fault zones and hard rock. Cross passages are provided about every 500 m of the 12 km long tunnel section. Different support types are required for the opening of the segment lining and connection to the excavation of the cross passage. In hard rock, the support consists of anchors, tail void grout and permanent bolts between the segments. In soft ground, a temporary pre‐stressed steel structure is provided, with longitudinal dowels at ring joints and special segments with increased reinforcement for the special case where cross passage excavation enters the segment‐lined tunnel.