Underground Mining Traffic tunnel construction
twin-tube railway tunnel
Deutsche Bahn trains have since 2012 been traversing the 9.4-km Katzenberg tunnel on the new four-track railway line between Karlsruhe and Basel at speeds of 250 km/h. The two 8,984-m underground tunnels were excavated using two EPB tunnel boring machines with an excavation diameter of 11.16 m. The construction was carried out using monocoque segmental expansion with a 60-cm shell thickness. The internal diameter is 9.60 m. The maximum thickness of the ground above the Katzenberg tunnel is about 110 m above the ridge. In the area of the north portal near Bad Bellingen, the tunnel was excavated under buildings at roughly 25 metres below ground level. Difficult geological conditions and high water inflows presented a major challenge to the implementation of this complex tunnel construction project. The two tunnel tubes running at a distance from one another of 16-26 m were connected at intervals of 500 m by connection tunnels with rescue locks. At the highest point, an 80-m-deep ventilation shaft with an internal diameter of 6 m was constructed for each tube.