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Hallandsas
Requirement
tunnelling project
 |
Employment | Railway |
|---|---|---|
| Geology | Gneiss, amphibolite, diabase dykes | |
| Tunnel Length | 11,000 m | |
| Diameter | 10,530 mm |
Solution
machine data
| Machine Type | Mixshield | |
|---|---|---|
| Support Techniques | Segmental Lining | |
| Cutterhead Power | 4,000 kW | |
| Torque | 20,370 kNm |
The train link between Malmö and Göteborg, on the Swedish west coast, is being upgraded to a high speed rail link. One obstacle standing in the way of this project is the Hallandsås mountains ridge, to the south of Bastad. Initial attempts to construct the tunnel by mining means failed because of geological conditions that proved difficult to overcome - principally high water pressures and deeply fissured rocks. The fresh invitation for tenders stipulated, amongst other things, that the tunnel had to be 5.6 kilometers in length, with an interior diameter of 9.4 meters. The tunnel had to be bored using mechanized tunnelling techniques. The contract was awarded to the Swedish-French Consortium, Skanska-Vinci.
Herrenknecht AG supplied Skanska-Vinci with a tunnel boring machine specifically adapted to the conditions that were to be expected. The Mixshield S-246 can be converted in the tunnel and can tunnel both in the closed slurry mode and in open hard rock mode. In slurry mode, the TBM is designed for sections with very high water levels (max. operating pressure 13bar). Permanently installed boring and grouting tools ensure that the influx of water can be restricted by cement grouting.In May 2008 – after completion of a considerable tunnel section – the jobsite scheduled a large-scale project: The cutting wheel was worn to such an extent that arefurbishment would have been uneconomically. To better fight the tough rock, a new cutting wheel with larger disc cutters (12 instead of 17 inches) was mounted. On August 25, 2010, a tough job has been successfully completed: after 5,480m the miners proudly celebrate the breakthrough of the first tunnel. Comprehensive maintenance works will be carried out before the TBM starts driving the second tube of the Hallandsås Tunnel.
