Brenner exploratory drive completed - TunnelTalk
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Exploratory bore for Brenner Baseline through Nov 2010
SELI News Release
The first step towards realising the 62.7km long Brenner Baseline rail link through the Alps between Italy and Austria is accomplished. On 3 November, a 6.3m diameter Wirth double shield TBM completed a 10.5km long exploratory tunnel between Aica and Mules to provide vital data and support information for the design and construction of the main tunnels to be driven deep into the mountains.
Exploration bore breakthrough

Exploration bore breakthrough

Two-and-a-half years after setting off the Wirth double shield TBM completed excavation of the 10.5km long tunnel according to schedule, driving generally through very hard and abrasive Brixen Granite with a compressive strength of up to 220MPa.
As one of the European Union's main TEN 1 infrastructure projects, the Baseline railway project will be the longest of its kind in the world and will reduce train travel times between Austria and Italy by 70 minutes.
The exploratory tunnel is constructed to investigate the geology, characteristics and behaviour of rock conditions likely to be encountered to minimise risks and verify budget cost calculations.
Brenner Baseline design

Brenner Baseline design

Excavation of the pilot tunnel started officially in April 2008 in the presence of Giorgio Napolitano, President of the Italian Republic. The exploratory bore contract was awarded in 2007 by European joint-stock company BBT-SE to an Austrian-Italian consortium comprising Pizzarotti, Condotte d'Acqua Spa, SELI Spa, Collini Spa, Bilfinger Berger, Alpine Bemo Tunneling and J├Ąger Bau. Under the leadership of Pizzarotti, the JV was in charge of all construction, with the exception of the tunnelling operations, which were contracted to consortium partner SELI.
Of the total €101 million contract, €54 million was paid to SELI for excavation and lining of the 10.5km tunnel.
As the 6.3m diameter double shield TBM advanced it erected 20cm thick x 1.5m long rings of five precast concrete segments.
The lining was designed and constructed in order to confront particular geological conditions including:
Segmentally lined bore

Segmentally lined exploratory bore

• Asymmetric thrusts,
• Sudden and violent rock bursts,
• Wide faults running parallel to the tunnel axis, and
• Pressurised groundwater inflows.
A special steel reinforcement was utilised along the area characterised by strong asymmetric thrusts.
The TBM advanced at an average daily output of 16m/day. Once dismantled and withdrawn, the project consortium will complete final operations that include
• construction of five niches to shelter transformers,
• removal of the continuous muck-hauling conveyor
• removal of other service equipment along the tunnel and
• dismantling of the external working site.
According to the contract, work is to be completed in February 2011.
References
Prelude to building Brenner Baseline - TunnelTalk, Mar 2009

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