The first caisson
is anchored at
“Superporto do Açú” in Rio de Janeiro
After a 4,200 nautical mile journey across
the Atlantic Ocean, the first caisson was an-
chored last 31 July at the Açú Port. This is
the first of a series of 47 floating caissons
that will comprise the future TX1 terminal
known as “Superporto do Açú”, in Río de
Janeiro (Brazil).
This activity represents a major technical
achievement. Until now, no floating caissons
had been shipped across such a long dis-
tance. This milestone is worth mentioning
due to its symbolical importance as the first
“stone” of the future mega-harbour.
The caissons were shipped in two different
phases in a semi-submergible vessel. Five
caissons measuring 45 metres in length, 24
meters wide, and 18 metres high were trans-
ferred in the first journey and, subsequently,
another four all measuring the same except
one that is 37 metres long, were transferred
in the second shipment. These caissons will
be used to build the seawall to protect the
floating docks Mar del Aneto and Mar del
Enol at their first station for manufacturing
caissons at Açú Harbour.
The caissons were downloaded at Rio de
Janeiro, at Guanabara Bay, from which they
were towed to their provisional destination at
Açú Harbour.
Are the weather conditions in Açú favou-
rable for the floating caisson solutions?
Is depth also important for these ma-
noeuvres?
“The sea conditions in Açú Harbour are very
complicated during the winter months (sum-
mer in Spain) for these types of operations.
This, however, was already taken into ac-
count in the preliminary project studies. Sta-
tistically, we were aware of our possibilities
for monthly anchorage. For example, our
“window of possibilities” this month for suc-
cessfully anchoring is for thirty, versus fifteen
during January of next year. “
Effectively, the solution of the floating cais-
sons as a building procedure cannot be
performed in all places and geotechnical
conditions determine the possibility of using
this procedure. In the case of Açú, we had to
dredge, with the work having been comple-
ted this week, 4.1 million m
3
of material from
the foundation ditch of the caissons over
which we dump the rockfill which will form
the foundations of the caissons.”
“This means that it could happen that the
volume of material to be “replaced” was so
large that it was not financially advantageous
and, therefore, the use of the caisson as a
construction solution was not financially or
technically advantageous. Nevertheless, in
Açú, because of the great depth required
for oil tankers that will be using the interior
berths, the use of the sloping wall dykes
would have meant that the project would
not be viable because of the huge amount
of quarry material that would have had to be
transferred in such a short period of time.
Moreover, as it could not be any other way,
environmental concerns mean that we must
use construction solutions that are less ag-
gressive with the environment and the im-
pact of the caissons is much less than the
equivalent sloping wall since the amount of
materials used for manufacturing the cais-
sons is significantly less”.
