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SAMC
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• ANNUAL REPORT 2013
Two offshore support vessels of similar capability
were compared; one with no ice reinforcement and one
with ICE-1C ice class. Both vessels were of a rather
conventional design, and with a modest bulbous bow. A
conventional harsh environment ultra-deep water semi-
submersible drilling rig was impacted. Figure 11 shows
the impact location. Vessel displacement is around 7500
tonnes, platform around 65 000 tonnes.
Figure 11. Vessel impact location to platform.
Figure 12 shows the resulting damage at similar levels
of dissipated kinetic energy. This corresponds to impact
velocities of 1 to 3 m/s for the 7500-tonne vessel. The
semi-submersible platform is designed according to
normal procedure, and is capable of crushing both the
forecastle and the bulb structure of the non-reinforced
vessel. However, when impacted by a reinforced vessel,
the bulb will not be crushed and the damage to the
platform increases quickly. The difference increases
with higher impact velocities.
Based on these findings, it is evident that vessels with
ice reinforcement should have different rules and
routines for operation around a normal platform than
a non-reinforced vessel if the same overall risk level is
to be obtained.
Friction of sea Iice on sea ice
Friction is one of the key phenomena during the interac-
tion of ice with offshore structures and ships, ice rafting
and ridging processes, and the brittle compressive
failure of ice. Therefore, knowledge of ice friction laws
and a better understanding of this phenomenon are
needed for the design of safe, reliable offshore struc-
tures and successful operations in ice-infested waters.
Dr. Sergiy Sukhorukov defended his doctoral thesis on
13 November 2013, where he presented experimental
studies on ice friction in the field and in the laboratory.
Sukhorukov was employed at Kværner in 2013 after
his defence. In this way, knowledge from the Centre
is transferred to SAMCoT’s industry partners and the
inter-collaboration of research groups strengthened.
His work can be divided into three parts:
• field study of ice friction and the effects of differ-
ent parameters on the kinetic and static friction
coefficients;
• investigation of geometrical stick-slip interaction
between ice and stainless steel in small-scale
laboratory tests;
• field investigation of the vertical ice forces exerted
on isolated vertical piles frozen in level ice due to
changes in the water level.
Figure 12. Deformation at 4, 11, 15 and 39 MJ energy dis-
sipation. Non-reinforced vessel (top) and ICE-1C vessel
(bottom).
Sukhorukov working in adverse conditions in an effort to
obtain the necessary data for his research.