Overbreak remedy at the Herzogberg

摘要

The A2 motorway is one of the major transport and trade links between Eastern and Southern Europe (figure 1). The existing 2km long Herzogberg tunnel is situated along the route in the mountainous region of the Koralpe, approximately 30km to the south-west of Graz, Austria. This NATM tunnel, with portals situated at an elevation of approximately 945m asl, and a maximum overburden of 145m, is part of a 22km long stretch of the motorway, constructed in the 1970s. The dramatic increase in traffic to approximately 20,000 vehicles per day and heightened Alpine road safety standards ultimately led to the decision to upgrade this section. Design of the project started in the mid 1990s, resulting in the 22km long section being divided into three lots. The "Herzogberg" lot is the first to be constructed with an overall length of 4.9km, comprising two bridges (386m and 185m long), 2.4km of open motorway, and a second Herzogberg tunnel tube. The project is funded by ASFINAG (Autobahnen-und Schnellstrassen Finanzierungs Aktienge-sellschaft), a government financing corporation, which transferred the overall project management and the site supervision to the local Styrian authorities (Amt der Steiermaerkischen Landesregierung). Prein-Lechner ZT GmbH provided the design and the tender documents, with the contract finally being awarded to the Herzog-bergtunnel JV, comprising Strabag, Hinteregger & Soehne, Porr Tunnelbau and Oestu-Stettin for US$48.4M. 3G (Gruppe Geotechnik Graz ZT GmbH) provides engineering geological services and consultancy for the client with surveying and geotechnical measurements performed by consultant Geodata GmbH.