Shafts

At STRABAG, we understand the importance of tunnel shafts for efficient and safe underground construction. These vertical passages connect the earth's surface with the tunnel and play a central role in various phases of tunnel construction.

Where depth is limited and the rock is less stable, vertical shafts can be constructed from the surface using the sinking method. We have successfully used this method, for example, for the two 70 m deep ventilation shafts of the Katzenberg tunnel. For greater depths and in stable geology, raise boring is used, which is currently considered the most economical method for constructing shafts. In this fully mechanical rod drilling method, a controlled pilot bore is first drilled to an already created cavity at the future shaft base. The pilot drill head is then replaced with the reamer. This is then used to widen the pilot bore to the final diameter, pulling upwards from below.

Raise boring can currently be used to achieve maximum diameters of around 6 m and depths of over 1,000 m. We have used this method to produce shafts for numerous projects, such as the ventilation shafts for the new DB railway line at the Bleßberg and Silberberg tunnels as well as the pressure shaft for the Vianden pumped storage power plant and in Alto Maipo in Chile. Thanks to our strong position in mechanized tunnelling, we have been involved in numerous hydropower plants and infrastructure projects with inclined shaft TBM tunnelling, including the Häusling pressure shaft and the Gerlos II hydropower plant. Other inclined shafts were drilled for the funicular railroads in Saas Fee and Les Deux Alpes.

The design of the shafts varies depending on the ground conditions in order to achieve optimal results in different geological conditions.
At STRABAG, we use our expertise to ensure the seamless integration of tunnel shafts into our projects, contributing to the success and safety of every project.