1. Together with its Australian
affiliate, the Baulderstone
Hornibrook Group, Bilfinger
Berger AG built a 660 m long
cable-stayed bridge over the
Mekong, 120 km to the south
west of Ho Chi Minh City in
Vietnam.
The four-lane bridge is an
important element in the
expansion of the infrastructure
in southern Vietnam and
improves the link between the
Mekong delta and Ho Chi
Minh City.
A special challenge was
presented by the foundations
for the abutments and the
pylons. This required the
construction of 36 large-
diameter bored piles with a
diameter of 2.5 m, reaching
to a depth of up to 100 m in
the Mekong river bed.
Work on the piles was per-
formed from a floating plat-
form, 75 m long and 24 m
wide, in water up to 25 m
deep, a tidal range of up to
two meters and a river current
running at a speed of up to
2.5 m/s.
The piles had to be partly
cased for lowering. After
lowering the 42.5 m long
casing in the river bed, it was
vibrated into place using a
vibrator. The suspension-
supported removal of the
excavated material was per-
formed with the help of a
special spherical grab deve-
loped by Bilfinger Berger.
The positioning and verticality
of the piles had to satisfy
extremely stringent specifica-
tions. After replacement of the
suspension, the reinforcing
cages, up to 80 t in weight
and up to 104 m long, were
inserted. The cages were
made in sections on the north
bank and transported on
pontoons to the required
position.
The placing of the concrete at
depths of up to 100 m made
special demands on the
formulation and placing tech-
nology. Special pipes with
strong, watertight couplings
were used.
The concrete was mixed in
plants on land and driven
over the 150-meter auxiliary
bridges to the point where it
was to be placed. Sponge-
like plastic balls were used to
separate the supporting liquid
from the concrete in the
tremie pipe.
Six pipes built into the rein-
forcing cage initially permitted
an integrity check to be ma-
de. In the following, they
served for grouting of the pile
foot in order to increase load-
bearing capacity. The bearing
properties of selected piles
were checked. For this pur-
pose, hydraulic presses were
built into the pile shaft. It was
possible to do without the
abutment which is normally
used in conventional test
layouts because the pile
weight and the skin friction
took over its function.
n Contract Value:
USD (m) 59.5
n Construction Period:
06/1997 - 03/2000
n Client:
Australian Agency for
International Development
n Services:
Construction of a
1500 m long bridge
founded on large diameter
piles
Reg.83-BB-607-20.2.700-00-A
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