Changed geology during the construction of the Karawanks Tunnel

After a delayed start on the Slovenian side, the construction of the second tube of the Karawanks Tunnel is now in full swing and the breakthrough already took place on March 18, 2024. With a length of 7.9 kilometers, of which 3,546 meters fall on Slovenian territory, the Karawanks Tunnel as part of the "Pan-European Corridor X" is one of the most important transport connections between Central and Southeast Europe.

During the excavation work on the southern, Slovenian tube, a change in the geology became apparent after the first 2,800 m of excavation. While the first construction section was defragmented rock, which was primarily secured with SN-Anchors, DSI Hollow Bar Anchors and LSC^™ Elements, type 4N, the geology improved to hard rock in the further construction phase.

Therefore, the support systems had to be adapted according to the new conditions. The construction company selected OMEGA-BOLT^® Expandable Friction Bolts for further installation. To control squeezing rock conditions, these are the optimal and fastest solution. Since OMEGA-BOLT^® Expandable Friction Bolts are ideal for continuing the project, the necessary tests for their further certification were carried out immediately. The tests required for this were executed by the ZAG, the Slovenian National Building and Civil Engineering Institute, in Ljubljana and led to the successful completion of the certification.

After the planned commissioning of the new east tube in the summer of 2025, the west tube will be renovated over a period of two years. In the summer of 2028, both tunnel tubes are then to be completely released for traffic.

DSI Underground is pleased to have provided a quick and optimal solution for the changed geology in this project with flexible support systems.