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Once the building of the dock had finished with the post-stressing,
the dry dock was flooded using 40 cm outer diameter pipes acting as a siphon
so that sea water passed over the retaining wall down to the approximate level of -7 m.
The total length of the pipes was 95 m and they were in continuous operation for three days.
To allow work to continue with the caisson floating,
an access walkway was built to it, spanning 39.3 m,
3 m wide and weighing 60 tonnes.
It was formed from easily assembled and disassembled metal modules.
Its special design allowed the for the movements of the floating caisson - 2 m horizontally
and the rising and falling of the tide - and it allowed trucks of up to 32 tonnes to pass.
Once the water tightness tests had been made,
the dry dock retainer wall was demolished
and an exterior channel dredged, 80 m wide and 15 m deep
This involved excavating 20,000 m3 with land equipment,
65,000 m3 with mechanical dredging and another 15,000 m3 with blasting.
The delicate exit manoeuvre from the dry dock was started with two 60-tonne capacity tugs and then with one.
As the dock exited the dry dock, another four tugs pushed against its sides.
The dock was controlled at all times with four winches on the banks of the dry dock,
two with twin drums and a pull of 100 tonnes per drum, and two single 50-tonne units.
Another two 50-tonne units were located on the joint side.
Six large bollards served as a support for the various corrections carried out in the manoeuvre.
Once it was out of the dry dock, four tugs towed it to one of the docks in the port of Algeciras
where a tanker boat ballasted it with 16,000 m3 of fresh water to give a draught of 15 m, needed for sailing to Monaco.
needed for sailing to Monaco.
The tasks before the arrival of the dock, such as sinking the piles and positioning the chains,
were carried out by the Russian ship Stanislav Yudin, 183 m long,
equipped with a 2,500-tonne capacity crane with a reach of 35 m.
The piles were steel tubes 75 mm thick with a diameter varying from 1 to 2 m and 20 to 25 m long, made in Germany.
They were sunk with a hydraulic hammer to depths of 50 to 80 m below the sea bed.
The operation to install the 10 definitive mooring lines for the dock
had few precedents in the world of civil engineering.
The positioning chains, eight on the inside end and two auxiliaries on the land end,
95 and 152 mm in calibre, were fixed to each pile by eyebolts
and to the dock with metal plates anchored by post-stressing in its sides,
with a mechanism to adjust their tension in the unlikely case
of an unusual movement in the exterior end.
The total length of the chains was 3,500 m.
These operations were carried out in November and December 2001
the free ends of the chains were fixed to a buoy 20 m below the sea surface, awaiting the arrival of the dock.
The dock was towed in August 2002 following a route that left the bay of Algeciras,
passing west of the Balearic Islands and arriving at the Principality of Monaco after 12 days’ sailing
and a journey of over 1,500 km at an average speed of 3 knots (some 5.5 km/h).
This route was chosen after exhaustive reports, considering numerous factors
such as waves, currents, predominant winds and possible weather conditions.
The dock was towed from the joint end by a 75 m long tug
with a power of 13,500 hp and a pull of 180 tonnes using a 75 mm cable 1,100 m long.
The two were escorted by a back-up tug 44 m long
with a pull of 100 tonnes and a power of 8,000 hp to help the main tug in the event of contingencies
and to house the computers that monitored the numerous sensors in the dock,
controlling at all times forces, temperatures and depths.
The dock arrived in Monaco on 26 August 2002 amid great expectation and celebration.
Once in Monaco, the operations to connect the dock
started by positioning it in its alignment with five tugs and a self-propelled pontoon,
keeping a separation between the joint and the caisson on the land side of some 10 m
and connecting and temporarily tightening the eight chains fixing its outer end.
Divers then removed the cover protecting the joint during the tow.
When the weather and sea conditions so allowed, the joint was moved towards the stirrup.
For the final connection manoeuvre
(it should be remembered that this involved moving a mass of 163,000 tonnes with a precision of millimetres),
three large steel girders were fixed to the dock to:
- the two side ones, each of 110 tonnes, to set the level of the joint,
supported on two vertical banks of 500-tonne hydraulic jacks on the land side of the caisson.
the centre one, weighing 80 tonnes, to guide the dock during the connection with two horizontal banks
of three 500-tonne side jacks on the land side of the caisson.
There were also large anchoring eyebolts for the cables to bring the dock up to the stirrup.
The approach was made using two double drum winches with a pull of 100 tonnes per drum
and a support tug for positional corrections.
The manoeuvre started in the early morning
and was monitored by a 3D representation showing the position at all times.
After some nine hours’ manoeuvring, the joint reached its final position in steps of 20 to 25 cm
and with error margins within a 1 cm diameter circle.
The joint was then fixed to land with a circle of bolts installed from the access provided in the stirrup caisson
and the anchoring chains were given their final tightening.
In the event of an earthquake, the design of the joint allows it to disconnect to prevent damage to the dock,
the reason for the two auxiliary chains on each side of it, also connected to piles,
which will keep it in position if the joint disconnects.
Finally, the connection tools were removed .
and the work on the superstructure in the space occupied by them was finished
The building of this harbour wall, completely innovative
innovative and with few precedents world wide, was possible thanks
to the support of the government of the Principality of Monaco, for a leading edge solution
to solve important geotechnical problems,
the lack of accesses and available space, and respect for the environment.
Secondly, due to the application of different technologies such as high strength concretes
with protection from the sea, the development of special post-stressing equipment
to thread 250 m cables with vacuum injection, the development of naval mathematical models of the forces
caused by waves and wind that are different to the traditional ones,
and such special metal constructions such as the joint.
And thirdly, due to the combination of human, technological
and financial efforts by the companies who undertook it, including FCC Construcción.
The project used over 44,000 m3 of concrete, more than 13,500 tonnes of steel,
40,000 m2 of coffering and the preparation of more than 40,000 drawings with over 150,000 hours of engineering.
All undertaken in conditions that respect the environment and the urban surroundings
... and at a reasonable cost.