e-mosty September 2018 Vessels and Equipment Used for Bridge Construction | Page 55

DRY AND WET DOCKS
Dry dock
Dry dock construction works comprised the following:
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Construction of retaining bund and revetments
for both the temporary and permanent sections.
Driving sheet piles.
Dewatering & Excavating of the existing land
down to specified bottom level of the dry dock.
Compaction of bottom of dry dock area.
Provide surface drainage system.
Road construction.
Dredging of approach channel.
Removal of temporary bund.
Final sweep.
Final removal of temporary bunds & dry dock
Dredging for the approach channel trenches was
performed from the offshore end towards land by
dredging equipment, mainly by back-hoe dipper dredger
and split dump barges, see Figure 2.
Construction of the wet dock comprised pile driving
works, RC plugs, in-situ deck slabs, installation of steel
catwalks and installation of a tower crane.
The piles were loaded on the barges using a crawler
crane. The service barge was then towed to the offshore
construction site using tugboats.
The tower crane was installed using a floating crane. Two
tower cranes had previously been installed on the
caissons in the dry dock.
TOWER FOUNDATIONS
The sequence of marine construction works for the North
and South Tower Foundations was as follows:
1. Dredging, transportation and disposal of dredged
material.
2. Inclusion piles.
3. Gravel bedding.
4. Caisson Construction.
5. Steel Shaft Installations.
6. Caisson towing and installation.
7. Plinth and tie beam construction.
8. Scour protection.
Dredging, transportation and disposal of dredged material
In order to create safe navigational channel, temporary
navigational buoys were installed at the determined
coordinates using the “Yaşar Doğu-I” Anchor Handling
tugboat.
A marine emergency response plan was followed in order
to prevent ship collision.
Figure 2: Dredging in front of approach channel
and underneath of dry dock retaining bund
After the dredging operations, a final sweep was done
using a harrowing technique, which involved towing an I-
Beam behind the ocean going tugboat “Yaşar Doğu-I”.
Wet dock
A temporary wet dock was constructed at the South of an
existing lagoon in Hersek Peninsula to berth the tower
foundation caissons for the completion of second stage
concreting works, installation of the steel shafts and
precast top slabs under the in-situ concrete top slab.
3/2018
Figure 3: Installation of navigation buoys