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46 SAMC
o
T • Annual report 2012
Sophisticated video camera systems for above and
underwater image capture documented the ice rubble
behaviour. The analyses done by image processing
software validate the trajectories of the ice rubble after
failure. In addition, the researchers used a buoyancy
box to monitor ice rubble behaviour and its mechanical
properties, e.g., cohesion and internal angle of friction.
Wenjun Lu, a PhD candidate at SAMCoT, joined the
project to study the ice-sloping structure interac
tion and is determined to find solutions that address
concerns for safety and reliability of vessels and struc
tures operating in the Arctic.
“I was lucky to participate in the study,” he said. “The
aim of my work is to develop an integrated ice-sloping
structure interaction model which permits modelling
the fracturing of ice. I want to capture the fracture and
fragmentation of ice with the cohesive zone theory.”
To demonstrate his point, Lu relays a realistic scenario:
“Imagine you’re drilling in the Arctic and an ice sheet
closes in on your structure. What do you do? How will
the structure and ice behave if they meet? What influ
ences the behaviour and, more precisely, what role do
fluids play? How important is the fluid when the struc
ture breaks the ice?”
Oda Skog Astrup also participated in the RITAS
project. Her SAMCoT Master’s thesis, Experimental
Investigations and Analytical Analysis of Ice Rubble -
Shear Box and Pile Testing, obliges her to establish
that previous HSVA freeze-bond strength test results
could be replicated and proved consistent with results
from the lab at NTNU. Skog Astrup also applied the
Mohr-Coulomb theory in model pile-up stability tests of
ice rubble used in the RITAS project, as well as evalu
ated the test method.
Henning Helgøy, a Master’s student at SAMCoT, found
his participation in RITAS both fun and interesting. “My
experiments aimed at investigating the strength of
individual freeze-bonds under similar conditions and
with equal ice properties as in experiments previously
performed at HSVA, and to investigate the reproducibil
ity of these experiments,” he said.
“I was particularly interested in the opportunity to
perform experiments demonstrating known and repro
ducible properties. However, collaborating with the
other participants and gaining valuable experience
planning and performing large scale experiments is
also an important point I would highlight as something
vital to our work at the HSVA,” he continued.
Helgøy used a variety of equipment to perform his
freeze-bond experiments: band-saw, hydraulic piston,
force measurement system and a microtome to make
thin sections, in addition to a trolley, a winch, and a
buoyancy box. “Because of my access to so many useful
tools during the RITAS project, I can demonstrate how
the freeze-bond strength varied with the contact area,
contact surfaces and time–temperature history of the
freeze-bonding ice-blocks, in addition to results of
comparing our experiments to the freeze-bond experi
ments earlier performed at HSVA”, Henning said.
Buoyancy box used to measure ice parameters and video
capture ice behaviour characteristics.
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