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Gotthard Tunnel

Gotthard Base Tunnel longest railway tunnel in the world

Project Details

With a length of 57 km, the Gotthard Base Tunnel is the longest railroad tunnel in the world.

Project Task

The Gotthard Base Tunnel is with 57 km length the longest railway tunnel of the world The drilling machines were blocked twice by collapsing rocks

Project Solutions

The Gotthard Base Tunnel was built across the Swiss Alps. Despite extensive probing, the Gabi II tunnel boring machine was buried under loose rock and rock.
The salvage plan called for an injection of cement to consolidate the loose rock. This procedure would have resulted in a total loss of the expensive TBM. A solution is being sought that will protect the tunnel boring machine from cement injection and allow it to be turned on again later.

HydroBloc Polygel 530 was a low-viscosity material that was able to penetrate the sometimes tiny cavities in the loose rock and protected the TBM from the cement slurry. Due to the long processing time, it was possible to pump the gel over long distances and achieve optimal distribution.
Another challenge was using standard cement pumps instead of stainless steel grouting pumps. This challenge could also be solved with the help of Hydrox AK 1011. The anti-corrosion additive for acrylate gels is added to the gel mixture and prevents any corrosive effect in the uncured state.

The soft yet stable properties of HydroBloc Polyel 530 enable the TBM to be turned without sticking to the drilling shield or interfering with transport. The solution was so excellent that the Consortium Alptransit also used this solution for the second accident.

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