H
errenknecht Tunnelling Systems,
the Germany-based manufacturer
of tunnel boring systems, used its
AVND2400AB tunnelling micromachine
to dig a new 2,200-m stormwater drainage
tunnel under the taxiway of the Dubai
International Airport.
The tunnelling crew of subcontractor Inter-
national Foundation Group, under the man-
agement of the main contractor M.A. Kharafi
& Sons, completed the project in March 2019
for the client Dubai Aviation Engineering
Projects Corporation.
Using the pipe jacking method, the
AVND2400AB machine with diametre of
3,025 mm, drive power of 315 kW, and torque
of 1,200 kNm excavated 610-, 765- and
825-metre-long sections under the taxiway. At
depths of 13 to 15 metres, the micromachine
crossed under the Terminal 2 taxiways while
fl ight operations on the ground and in the air
continued smoothly and safely. On the longest
drive, an average of 15 metres of tunnel per day
was excavated through soft soils comprising
sandstone and siltstone. The drive remained
on course with precision by using means of
Herrenknecht’s VMT navigation and control
systems.
The tunnelling was carried out without in-
terrupting fl ight operations at the airport. The
new tunnel increases the airport’s drainage
capacity and will ensure that rainwater does
not accumulate on the surface. This is crucial
to maintaining smooth fl ight operations at
the Dubai International Airport which han-
dles nearly 90 million international passen-
gers every year, making it one of the busiest
airports in the world.HERRENKNECHT EXCAVATES STORMWATER
DRAINAGE TUNNEL UNDER DXB TAXIWAY
TUNNEL BORING MACHINES
with the suspension. The excavation diameter
can be enlarged using an upsize kit and a
modifi ed cutterhead.
Herrenknecht has completed a number
of similar tunnelling projects at airports
worldwide. For the extension of the baggage
handling system at Zurich’s Kloten Airport,
a Herrenknecht Mixshield (Ø 6,280 mm) ex-
cavated a 2,400-metre-long tunnel under the
airport grounds until 2001. In 2002, an EPB
Shield (Ø 6,460 mm) tunnelled under the
Minneapolis-St. Paul Airport in the United
States for the newly developed 18.6-kilometre-
long light rail system. In Brazil, an AVN1500
constructed a 367-meter-long stormwater
drainage tunnel under the runway at Goiânia
Airport in 2015.
In 2017, two EPB Shields (Ø 6,250 mm) com-
pleted two new tunnel tubes for passenger and
baggage transport with a total length of 3,842
metres under the runways at Moscow Airport
Sheremetyevo in Russia. In 2018, during the
excavation of a 4,500-meter-long metro tunnel
in Barcelona, a taxiway at El Prat Airport was
crossed over a distance of 70 metres.Herrenknecht AVN machines belong to
the category of closed, full face excavation
machines with a hydraulic slurry circuit,
and they are employed for tunnelling in the
diameter range of 0.4 to around 4 metres. The
slurry-supported excavation concept makes it
possible to use these machines in all kinds of
ground conditions such as silt, clay, incohesive
soils, gravel and rock. Depending on the diam-
eter, this is possible both in pipe jacking and
for segmental lining. The soil to be excavated
is removed using a cutterhead adapted to the
respective geology. This makes it possible
to use the machines in almost all geological
conditions. In soft soils and mixed geolo-
gies, standard or mixed ground cutterheads
are used, while a rock cutterhead with disc
cutters is used for tunnelling in stable rock
formations. A cone-shaped crusher inside
the excavation chamber crumbles stones and
other obstructions to a conveyable grain size
while tunnelling and advancing. Subsequent-
ly, the material falls through openings similar
to a strainer in front of the suction port and is
then removed through the slurry line togetherPEAK PERFORMANCE
46PLANT / MACHINERY / VEHICLES AUGUST 2019 http://www.pmvmiddleeast.com