February 16, 2006: An overview of the Mammoet strategy
This is the story that Sparky and I are watching unfold.
Mammoet a Dutch company has their team
from Ontario here to install the hydraulic jacks and cable assemblies that will
be used to lower the main spans of the Pearman and Grace bridges to
barges-in-waiting (February 22).
Tuesday morning this is what the Grace and Pearman worksites looked like from
D-25. The Grace skeleton (roadless compliments
of Pio's team) is on the left with the jackup barge under one of the pins that
tie the cantilever truss to the main span truss - and the Pearman is
to the right.
The Grace worksite. The jackup barge for working under the Grace skeleton
and the crane for working above the Grace skeleton.
There are a pair of pins on each side of the bridge that couple the
cantilever truss to the main span truss as shown here for the Pearman Bridge.
The Pearman (foreground) and Grace (behind) main span segments. Note
the platform installed on the left of the Pearman truss on the cantilever
side of the coupling pins.
A closer view of one of the Pearman coupling pins.
The platform (above top left) is the home of the hydraulic jack assembly that
Mammoet will operate.
The Grace pins (seen through the crane)
At this time, someone was working on the bottom side of the Grace from
the jackup barge.
Here is the pin Grace assembly
and a seagull watching carefully to make sure her resting place is not
distrubed
A worker on top of the Grace at the pin location
Getting into the elevator.
and a view of the Ravenel Bridge with the Grace and Pearman symphonies
practicing for next week
Meanwhile yesterday, Sparky captured the unloading of the hydraulic
jack and cable assemblies. The jack is in the center and the upside down
U is the umbrella over which the cables will ride. The jack operates
the in a similar manner to the
jacks used by Freyssinet to tension the Ravenel stay
cables. In the case of Freyssinet, a single cable was tensioned. Here,
it appears that the entire ensemble of cables will be hydraulically controlled
with a ratchet-like movement - maybe a foot at a time (my guess). Notice
that there are two teams, the
Red team (Mammoet) and the
Orange team (Testa).
Here the jack / umbrella assembly is being lowered onto the
barge with the cables passing over the umbrella
Here are the ends of the cable bundle that (my guess) will be tied into
a platform installed on the main span ends. Notice that this man
is part of the red team (Mammoet) in contrast to the orange
team of Testa
Both the Red and Orange teams working together
Lowering the jack / umbrella / cable assembly. On the surface of the
barge is a pair of jacks tied together on a beam that will rest across
the top of the each end of the Pearman cantilever section.
and lowering it onto a barge
Stay tuned
