THE second
tunnelling drive on the 16km twin-bore tunnel beneath the Chiltern Hills for
Britain’s HS2 high-speed line between London and Birmingham was completed on
March 21.
The second
tunnel boring machine (TBM) to be deployed on the project, named Cecilia, broke
through at the tunnel’s northern portal near Wendover after completing the
drive that began in June 2021.
The first drive
on the HS2’s longest tunnel was completed by TBM Florence on February 27.
The two
2000-tonne TBMs have excavated the twin bores at a depth of up to 80m,
excavating 3 million m3 of chalk.
The TBMs have each also installed and grouted into place 56,000
fibre-reinforced concrete tunnel lining segments, proceeding at an average rate
of 16m per day.
Both machines
were launched from the tunnel’s southern portal, near the M25 motorway, and
were operated by main works contractor Align, a joint venture of Bouygues
Travaux Publics, Sir Robert McAlpine and VolkerFitzpatrick.
According to
Align’s underground construction director, Mr Didier Jacques, completing the
two 16km drives has been technically complex, given that the average drive for
a TBM is around 5km. “I am delighted that as a team, we have risen to the
challenge,” he says.
