SEGMENTAL | LINING


considering: Pretensioned steel arches; resource efficiency in segmental lining systems with butt-jointed reinforcement of the longitudinal joint; steel fibre reinforced concrete segments on Grand Paris Express project; using fibre optics for monitoring of segmental lining on Brenner Base Tunnel; and, design and construction of pressure tunnels.


Hydraulic Underground Structures: The theme on Hydraulic Underground Structures is to hear presentations on geotechnical aspects of the exploratory tunnel for Coire Glas pumped storage hydropower project, in Scotland; overview of EurCOLD information on underground conveyance structures (penstocks, pressure tunnels, and shafts); briefing on the Forbach pumped storage project under construction in Germany; discussion on pressure shaft optimisation


for Limberg III pumped storage project, in Austria; and, a briefing on design and construction of the Ebensee pumped storage project, also in Austria (which is also the subject of a separate site visit, immediately after).


TECHNICAL VISITS This year’s Geotechnical Congress also features a planned all-day excursion to Brenner Base Tunnel rail project (see box panel), on the first day, 8 October, as an alternative option to the workshops. On the last day of the event, 10 October, another major excursion is planned, this time to the underground works for the Ebensee pumped storage project .


For more details on OGG’s 2025 event, go to: www.geomechanics-congress.com


SOME SEGMENT PRODUCTION ON BRENNER BASE TUNNEL


S.p.A. Segment production started in late 2017 and continued to late 2024. In total, the factory produced almost 218,250 concrete segments. For the lot, each concrete ring is made up of seven segments plus one base segment on the two main rail tunnels and two base elements for the exploratory tunnel. The factory manufactured nearly 26,000 concrete rings and more than 38,000 base segments for the lot’s main tunnels and the exploratory tunnel. More specifically, there were 16,285 concrete rings and 16,298


base segments produced at Hinterrigger for the main tunnels, plus 9,456 rings and 21,762 base segments for the exploratory tunnel.


Above: two-deck caption


Brenner Base Tunnel is a huge, multi-year rail transport construction project being undertaken by Austria and Italy, mostly as bored tunnels under the Alps and passing below their border. It is being developed by the special owner-operator company BBT-SE. The scale of construction called for the works to be split into multiple large lots, and the overall project is at an advanced stage of execution. Preparations for setting up the equipment and materials to


support the enormous tunnelling works had to begin early. These have been large-scale endeavours in their own right, lasting years. Two such major operations involved establishing factories to produce concrete segments for the bored tunnels on two separate lots - Lot H61 Mules 2-3 and Lot 41 Sillschlucht- Pfons, respectively


H61 Mules 2-3 The concrete casting factory for Lot H61 Mules 2-3 was built in Hinterrigger, near Brixen, and operated by Isocell Precompressi


Each segment of the main tunnel weighs an average of nine tonnes, while a segment for the exploratory tunnel weighs half that. Approximately 30% of the excavated material from TBM boring on the lot was used in concrete segment production. The segments were transported to site by rail. A consortium of Webuild, Ghella, Cogeis and PAC has operated three TBMs on the lot.


Lot 41 Sillschlucht-Pfons Concrete ring production for Lot 41 Sillschlucht-Pfons finished in July this year after casting approx. 59,000 segments since early 2023. The purpose-built concreting factory is located near Brenner’s


Ahrental portal and BBT-SE noted that output averaged about 90 segments per day. With no rail transport locally, this arrangement on-site helped to avoid the large numbers of truck transportation runs that would have been required by road. The factory has a storage area from where a dedicated local rail transport takes the segments to the tunnels. Following the set-up of a circulation system for the segment manufacture, part of the factory is to be reused to make rebar cages.


September 2025


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