The Südbahntagung conference was initiated in 2008 as a forum at which findings and case studies on major tunnelling projects in Austria such as the Semmering Base Tunnel, Koralm Tunnel and the Granitztal valley chain of tunnels as well as other projects on the southern line (Südbahn) could be presented and discussed. The 2015 event was held on November 27 and 28 in Graz – involving more than 250 participants mainly from German-speaking countries. The conference was organized by the Institute for Rock Mechanics and Tunnelling at the TU Graz in conjunction with the Montan University Leoben, the ÖBB-Infrastruktur AG, Vienna, and the Austrian Society for Geomechanics (ÖGG), Salzburg.
The southern line rail route forms the Austrian part of the Baltic-Adriatic axis, which links the Baltic Sea with the Mediterranean and the Upper Italian economic region. The Semmering Base Tunnel, the Koralm Tunnel and the Granitztal and St. Kanzian tunnel chains represent the main projects under construction in conjunction with the southern line with a total of 70 km of tunnels. In addition, the southern line also involves numerous schemes on the surface such as upgrading stations and building new ones, a free route section, cut-and-cover tunnels and bridges.
On the opening day, leading experts from science and industry dealt with current projects in 13 papers providing concepts for solutions. They reported on experiences made as well as on research and development linked to these projects.
The Koralm Tunnel Project
The 32.9 km long Koralm Tunnel with two single-track tubes represents the core of the Koralm Railway with cross-passages at 500 m gaps and overburden of up to 1,100 m. One paper dealt with the application of the third tunnel boring machine (TBM) since October 2015 in the north bore (contract section KAT3) and the planned conversion of this multi-mode TBM after excavating 4.5 km in the Lavanttal Fault for the subsequent 7.5 km up to the breakthrough with contract section KAT2. The machine is to be modified from a shield machine to a hard rock version. Then, findings obtained during the cyclic drive in the crystalline section of contract section KAT3 were examined. A report on dealing with tunnel muck in a responsible fashion taking the example of contract section KAT2 followed.
Granitztal and St. Kanzian Projects
The 6.1 km long Granitztal Valley tunnel chain, mainly comprising the Deutsch Grutschen (2.6 km) and Langer Berg (2.9 km) tunnels, each with two single-track bores, has been under construction since early 2015 and forms the Koralm Railway’s second longest tunnel section. From the total of six structures comprising the chain, the 496 m long, so-called Kühnsdorf “Green Tunnel” – a noise abatement tunnel with greenery – has already been built by cut-and-cover. Work began on the Peratschitzen Green Tunnel (230 m long, cut-and-cover) and the Srejach Tunnel (620 m long, top cover method) in summer 2015 and the Untersammelsdorf (665 m), Stein (2.1 km) and Lind (495 m) tunnels are due to be embarked on in spring 2016. Special geological challenges are posed by dead water sediments and the shallow overburden.
Semmering Base Tunnel
The necessary permits from the Federal Administrative Court for building the 27.3 km long Semmering Base Tunnel (SBT) with two single-track tubes between Gloggnitz and Mürzzuschlag have been available since May 2015 after many years of protracted difficulties. Work began on the Gloggnitz section on July 1, 2015. In addition, the challenges posed by the SBT 1.1 contract section (Gloggnitz Tunnel) and special aspects relating to tendering for contract section SBT 3.1 (Grautschenhof Tunnel) were examined.
Following a report on the state of the art for embedding segments, the distribution properties of pearl gravel and improvement measures, the conference’s first day wound up with a presentation of 3D images for data processing in tunnelling.
Day Two provided opportunities to visit a Granitztal tunnel chain construction site. The next Südbahntagung is scheduled for autumn 2017 at the Montan University in Leoben.