Sedrun tunnel, lot 360, AlpTransit, Gotthard Base Tunnel
Construction of two parallel single-track railway tunnels using blasting, and construction of a multi-function station.
Context: The Gotthard Base Tunnel (GBT; German: Gotthard-Basistunnel, Italian: Galleria di base del San Gottardo, Romansh: Tunnel da basa dal Son Gottard) is a railway tunnel through the Alps in Switzerland. It opened on 1 June 2016, and full service began on 11 December 2016. With a route length of 57.09 km (35.5 mi), it is the world's longest railway and deepest traffic tunnel and the first flat, low-level route through the Alps.
Railway tunnel with two single-track tunnel tubes, each approx. 9.0 km long, excavation cross-sections 60–134 m2 (full excavation), cross-passages every 312 m.
Multi-function station (MFS) with longitudinal and transverse caverns, four tunnel changeover expansions (excavation cross-section up to 230 m2), tunnel changeover connections, side tunnels, ventilation tunnels and 14 ventilation shafts, 4 maintenance halls.
Access via tunnel, length approx. 1 km, and two shafts with a depth of approx. 800 m. Challenge: highly complex installations.
Services in detail
Blasting, securing with shotcrete, anchors, netting.
Special heading in squeezing rock zones (northern part of the Tavetsch intermediate massif), securing with deformable steel structures, anchors, shotcrete, solid stabilisation of the working face.
In-situ concrete tunnel lining.
Shaft II: raise drill with subsequent expansion using shaft boring machine (diameter 7 m).
Clavaniev zone (CZ), Tavetsch intermediate massif (TZM)
Urseren Garvera zone (UGZ), Gotthard massif
Special heading under tough geological conditions (squeezing rock, radial convergences of up to 70 cm).
Challenging logistics: Supplying the construction site via an approx. 1000-metre-long access tunnel and two approx. 800-metre-deep blind shafts.
Reusing and processing the excavated material for producing the concrete (in-situ concrete approx. 328,500 m3 and shotcrete approx. 222,500 m3).
Total excavation volume 3,700,000 m3, total weight of arch structures approx. 20,000 tonnes of steel.