Page 10 - TunnelTalk Annual Review 2015

Global connections
Brenner attack
European Union funding, adding to funding by Austria and Italy.
The remaining main tunnel works on the Italian side, in the section known as Mules (Mauls) 2 and 3, involves approximately 14km of exploratory tunnel and a total of 36km of headings for the main tunnels. These works are set to take about nine years.
The main tunnels will run about 70m apart and are to be connected every 333m by cross passages. Multifunctional emergency stations, with direct access to the surface, will be located at 20km intervals.
Earlier works on the Italian side involved both TBM and drill+blast excavation for the exploratory tunnel, as well as opening up short sections of the main tunnels. BBT-SE is to commence procurement in 2016 for the main tunnels lot on the Austrian side, to the border which is estimated at €1.8 billion. n
References
• Brenner Base Tunnel river undercrossing award – TunnelTalk, Nov 2014
Patrick Reynolds for TunnelTalk
The latest TBM on the Brenner Base Tunnel project was launched for excavation of the 15km-long stage of the central exploratory tunnel on the record-breaking rail scheme through the Alps between Austria and Italy.
JV Strabag/Salini-Impregilo launched the 7.93m diameter Herrenknecht TBM on the Tulfes-Pfons Lot (T-PL) at the end of September. The JV was awarded the contract by project developer BBT-SE in mid-2014 and began with early drill+blast excavations. The contract involves a total of 38km of both TBM and drill+blast excavation in the complex layout at the northern end of the scheme, near Innsbruck (Fig 1). Geology along the alignment is mostly quartz phyllite, although the TBM will also pass through shale. Nicola Meistro, a manager in the Salini-Impregilo’s domestic operations division, told TunnelTalk that the challenges posed by the geology include optimising against the high abrasivity of the quartz phyllite and crossing the fault zone between the quartz phyllite and shale.
The TBM section of the T-PL is focused on the 15km portion of the exploratory tunnel from the Ahrental adit. One more stretch of the exploratory tunnel, from the Wolf adit onward, will be completed as part of a larger package that will include works for the 8.1m i.d. running tunnels.
NATM drill+blast excavation totals approximately 23km, accounting for the majority of tunnelling on the contract including the emergency station tunnel at Innsbruck.
The underground works have more than 23 different tunnel cross-sections, the largest
up to 250m2 (20m wide x 15m high). All T-FL works are scheduled to be completed by March 2019.
Salini-Impregilo and Strabag are also working together on a separate JV with other companies at the southern, Italian end of the project, at the Isarco River Underpass near Fortezza station. Work started on this section in late 2014 and calls for jet grouting to strengthen the local soil and ground freezing under the river.
To fund the mega international project, Italy formally approved a further tranche of €920 million, clearing the way for further procurement to proceed on the Italian side between the Mules adit and the border with Austria.
BBT-SE also received approval of a major tranche of the total €1.18 billion of
Fig. 1. Plan of the project; Insets: TBM and NATM works for the Tulfes-Pfons Lot
Ceneri Base Tunnel celebrations
TunnelTalk reporting
After five years of drill+blast
excavation from the central cavern
at the end of the TBM bored adit, first breakthrough of the southbound tunnel of the 15.4km Ceneri base tunnel into the portal at Vezia was achieved.
The final blast in March 2015 marked completion through the southern end of the west bore and into the 400m long drill+bast heading north from the Vezia portal. The joint venture of Condotte and Cossi was awarded the tunnel contract in 2009 for a
price of CHF987 million (€944 million).
Final breakthrough of the parallel southbound tunnel was expected in April 2015, with breakthroughs of the opposite northbound headings towards Vigana
portal expected at the beginning of 2016. Once complete the Ceneri tunnel will be integrated with the new Gotthard base tunnel into the existing Gotthard Railway route between Switzerland and Italy, significantly reducing journey times through the Swiss Alps by bypassing existing high altitude routes where speed is restricted by steep
gradients, tighter curves and overcapacity. Excavations on the 57km long Gotthard Base Tunnel were completed in 2011, with the railway line expected to become operational in 2017. The Ceneri Tunnel is on target to be
operational two years later, in 2019.
Work on the Ceneri tunnel began in June 2006 when geological data concluded that TBM operations would be restricted to excavation of the access adit, with base tunnel excavation split into two drill+blast drives heading outwards from the adit cavern located half way between
the two portals in Switzerland.
In April 2007 the Consorzio Monte Ceneri (CMC) JV of CSC, Lugano, Frutiger SA, Thun, Rothpletz, Lienhard + Cie, and Aarau, procured a 9.7m Robbins main beam TBM to bore the 2.4km adit tunnel. The machine was dressed with 19in cutters, which are designed to offer a higher cutter load, longer cutter life, and fewer cutter changes.
The adit tunnel was completed on schedule in November 2008 after ten months operation. A total 30 cutter rings were changed during the last kilometre, with the cutters excavating a combined 160,000m3 of hard rock. Daily advance rates averaged 18.5m which is claimed by Robbins as approximately 61% higher than the averages achieved by similar machines procured to excavate sections of the Gotthard Base Tunnelusing17incutters.n
References
• Ceneri Base Tunnel start – TunnelTalk, November 2008
• Final finish for Gotthard Baseline excavation – TunnelTalk, March 2011
• History in the making at St Gotthard – TunnelTalk, October 2010
Breakthrough celebrations at Vezia
Fig 1. Ceneri Tunnel excavations
10
TunnelTalk AnnuAl Review 2015 www.TunnelTalk.com
GLOBAL CONNECTIONS
PREVIEW