Bad Cannstatt Tunnel – Pit for Smoke Removal Structure
The Bad Cannstatt Tunnel is being advanced within the scope of the major project Stuttgart 21, approval section 1.5, Lot 3. The approx. 3.8 km long railroad tunnel will connect Stuttgart Main Station with the new Neckar Bridge.
In order to provide mechanical ventilation of the tunnel and Stuttgart Main Station in the event of a fire, several smoke removal structures must be built. This project also includes the smoke removal structure near the intersection of Heilbronner and Moenchhalden Streets. It incorporates a ventilation shaft that will be connected to the tunnel tubes via ventilation galleries. The structure consists of a mainly subterranean operation and ventilation building, two 5 m high vent stacks above ground and a staircase.
Installation of semi-permanent strand anchors
The excavation was built using a Berlin-type support system and tied back using strand anchors. Construction work is scheduled to take more than two years. Therefore, semi-permanent anchors were used instead of temporary anchors because they are suitable for a service period of up to 7 years.
An internal company approval from the Client – the Deutsche Bahn (DB) AG – was necessary before the semi-permanent strand anchors could be used. As the DYWIDAG strand anchors comply with a general technical approval, they were approved by the test association Dr.-Ing. A. Städing; DSI's customer GBS Grundbau received the DB AG's permission for installing them.
419 semi-permanent strand anchors including anchor heads were installed in the walls of the Berlin-type support system. The strand anchors had a total length of 8,750 m and a total weight of 40 t.