International Construction - April 2014 - page 45

45
april 2014
international
construction
TUNNELLING
Unique challenges
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The US$ 3.1 billion tunnel is a replacement for the Alaskan
Way Viaduct, and was initially scheduled to be completed by
September this year, and operational by December 2015. The
difficulties being faced by Bertha serve to highlight how critical
the smoothprogressofTBMs are to thecompletionof tunnelling
projects.
New tools
Elsewhere in the sector, manufacturers continue towork closely
with contractors to boost productivity and safety, developing
customised equipment from new excavation units to flexible
formwork designs.
GTAMaschinensysteme, for example, specialises in building
machines that run on monorails for use in tunnels. It has
introduced two new machines designed to support specific
aspects of tunnel lining and excavation.
Thefirst is amultifunctional uphill excavator, developed for the
Crossrail metro project in London, UK – currently the largest
infrastructure project inEurope (see box story).
GTA said the machine was designed and produced in six
months, andwas introduced inOctober last year.While themain
tunnels for the Crossrail project are driven byTBMs, secondary
incline shaftsneed tobedugout to connect theCrossrail stations
to the new subway lines. The idea is that escalators will be
installedhere once complete.
These incline shafts are being driven from TBM-level to
subway-level (bottom upwards), and GTA said the 30
o
tunnel
incline was not possible to tackle with floor-bound machines.
The uphill excavationmachine and its working platform are also
suspended on two overhead monorail tracks, and moved along
byGTApush-pull units.
Themachine features four breaking trolleys to keep it safe and
secure at steep inclines, and digs forward using a specialised
shovel. It alsoboasts adrill feed andbeused todrill blast holes in
case hard rock ismet, aswell as a hydraulic hammer for breaking
up rock, and a nozzle and lines for shotcreting.
Another new machine from the manufacturer is the TAM
7500A liningmachine for subway tunnels–apieceof equipment
developed with the idea of mechanising the installation of cast
iron or steel tunnel lining segments.
TheTAM7500A is a28 tonnemachine,
also suspendedon twooverheadmonorail
tracksmounted on the inside of a tunnel.
An additional rail track is suspended at
the side and is used as travel rail for the
transport unit. The machine has two
booms which are separately mounted in
two guideways, where they can bemoved
Crossrail’s 8th TBM launches
Progress on largest construction site in Europe continues
T
heUK£ 14.8 billion (US$ 24.6 billion) Crossrail metro project in London, UK– the
largest construction site in Europe – is progressing quickly, with the eighth tunnel
boringmachine (TBM) launched in February.
Developer Transport For London is building the project, whichwill pass through 38 stations
and run fromMaidenhead andHeathrow in thewest of the country’s capital to Shenfield and
AbbeyWood in the east.
Manufactured by Herrenknecht, TBM Ellie began its 2.7 km journey fromPuddingMill
Lane to Stepney Green in London’s East End on 25 February, at depths of up to 30m below
ground. The tunnel will form part of Crossrail’s north east spur fromWhitechapel to Shenfield
in Essex.
At 150m long and 7.1m in diameter, Ellie is staffed by 20 people andweighs 1,000
tonnes. Its sistermachine, Jessica, completed the journey fromPuddingMill Lane to Stepney
Green on 3 February, and in the comingweekswill be taken to Limmo Peninsula near
Canning Town in east London, where shewill beginCrossrail’s last tunnel drive towards
VictoriaDock Portal.
Crossrail recently passed the halfway point in its construction, and is said to be on time and
within budget. Over 30 km out of 42 km of bored tunnels are now complete. The eight TMBs
will construct ten different tunnels, with tunnelling 70% complete.
A customised Variokit tunnel formwork
solution from Peri is said to have sped
up construction on the 228m long
Marchlehner gallery on a road situated
at a height of 1,800m above sea level
in Austria. The gallery is designed to
provide protection against avalanches
and falling rocks.
Sandvik DT820 tunneling jumbos supported contractor Afcons
Infrastructure in redeveloping India’s 65 kmNational Highway
1, a US$ 350million project that included four twin tube
tunnels through the Himalayanmountains totalling 1.5 km.
1...,35,36,37,38,39,40,41,42,43,44 46,47,48,49,50,51,52,53,54,55,...60
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