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SAMC
o
T • Annual report 2012
floating structures are relevant to any location where
sea ice represents the major design feature and there
are a number of oil and gas development projects in new
frontiers where such sea ice conditions apply.
Karl-Ulrich Evers, Senior Project Manager in Arctic
Technology Department at Germany’s Hamburg Ship
Model Basin (HSVA), confirms. “Exploration and indus
trialisation activities in the Arctic are increasing and
only a few full-scale data regarding ice interaction with
offshore structures have been collected. Therefore, it
is necessary to combine several approaches in order to
develop a design methodology for offshore structures
operating in ice-covered regions,” he said.
In Spring 2012, SAMCoT Masters and PhDs candi
dates participated in an HSVA lab-based study to
further knowledge and understanding of the effects
of sub-surface rubble ice on offshore structures.
Designated RITAS (Rubble Ice Transport on Arctic
Structures), the research project utilized HSVA’s expan
sive hydrodynamic research resource, the Large Ice
Model Basin.
Nicolas Serre, Arctic Marine Technology leader for
Multiconsult, which headed the project, said, “This is
the first time that the ice breaking process has been
monitored in the vertical plane below the waterline and
related to measured ice breaking loads. It gave valuable
insight into understanding the different components of
the ice action on Arctic structures.”
RITAS gave the participants a unique opportunity to
design a research campaign targeting specific needs
of the industry and to enhance the technology levels,
while also pointing out needs for further developments
and services needed by the industry. SAMCoT provided
key competence to the project, creating a cooperation
and meeting point among international actors, includ
ing major industry companies, research institutions, oil
companies and suppliers. Moreover, Dr. Serré stated
that cooperation within the SAMCoT project revealed
there is a lack of comprehension on the mechanical
processes linked to the level ice interaction with Arctic
offshore structures.
“The tests confirmed that ice density has important
effects on the magnitude of the ice breaking load. The
tests gave us some surprises in terms of how steady
state ice breaking loads are correlated to broken ice
accumulation on the structure faces. This result may be
in contrary to current ice breaking load theories,” said
Dr. Serré.
The project was initiated, planned and led byMulticonsult
in Tromsø. NTNU and HSVA provided additional exper
tise and support for the planning, performance and
analysis of the tests. “Statoil acknowledged the project
as an important research topic and contributed with
additional funds, which is highly appreciated because
the tests results are available to everyone,” said Dr.
Serre.
The HSVA facility is ideally suited to experiments
concerning transport system and ship technology
research in open water and ice environments. The
HSVA’s 78m x 10m x 2.5m ice basin generates air
temperatures as low as -20°C, with properties of
the model ice scaled to simulate natural icebreaking
processes. A computer-controlled, x-y motion (planar
motion) carriage simulates ice drift scenarios with slow
or rapid ice drift direction changes against offshore
structures or floating vessels.
Amodel specially designed by Multiconsult for the RITAS
project was built by the researchers at the Hamburg
location. The model features an inclined slope at (and
below) the waterline and is outfitted with sensors to
measure forces and movements induced by ice.
This sloping waterline model built
by SAMCoT and HSVA researchers
at the HSVA Arctic basin venue is
outfitted with sensory scales to
measure ice force and movement
generated by ice failure.