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Rockfall at the B99 Katschbergstrasse (Austria)

Project overview:

On December 31st, 2003 a huge rockfall with a mass of approximately 4000 to 5000 m³ blocked the road B99 Katschbergstrasse. Due to a possible expansion of the mass movement also the motorway located above the slope was endangered. As more areas with much smaller (potential) rockfalls were detected during the geological and geotechnical site investigation the focus area was extended beyond the outlines of the actual landslide.

The in-situ brown to grey mica schists with a schistose to laminated structure show a significant loosening and weathering. As also joints were partly opened up to 10 cm, there was a high risk for further rockfalls.

The construction work started in June 2003 applying anchor ribs, shotcrete and rock bolts, protection fences and the removal of loose rock masses.

For long-term monitoring of the slope load cells and geodetic measurement points were installed on the site.

Services provided:

  • Geological field mapping and ground investigation by core drillings
  • Geological and geotechnical description of the site
  • Suggestions for the installation of different  earth retaining systems (anchor ribs with pre-stressed anchors, shotcrete with rock bolts, SN- and MAI-anchors, etc.) and protection fences as well as the removal of endangered rock masses
  • Static analysis and design for construction
  • Tender work
  • Geotechnical documentation, site supervision during construction and long-term monitoring

Client: Amt der Kärntner Landesregierung, Abteilung 17B - Brückenbauamt

Period: 2000 to 2004