Basic HTML Version
20 SAMC
o
T • Annual report 2012
Several means of station-keeping can be utilized,
including mooring- and dynamic positioning. A dynamic
positioning solution can be especially attractive for drill
ing, since drilling is a short-term operation and costly
moorings and anchor handling can be avoided. Mooring,
which is most often used for production platforms, must
frequently be combined with ice management.
SAMCoT research focuses on better understanding the
interaction processes between structures and ice. This
research entails multibody dynamics and hydrodynamic
effects on the interaction process.
Waterline Processes
Fracture of ice at different scales is frequently ob
served during the interaction between ice and offshore
structures. On large scale, we may observe the split
ting of ice floes, while locally at smaller scale, the bend
ing failure of ice is constantly taking place (see Fig. 8).
Furthermore, after the bending failure of ice, the bro
ken ice rotates downward. The ice rotating process is
coupled with the fluid, which represents the so-called
ventilation and backfill effects (see Fig. 9). Each of the
aforementioned processes take place at the waterline.
Doctoral student Wenjun Lu is making large achieve
ments in modelling the waterline processes and to
more precisely predict the ice load and rubble genera
tion at the waterline. “I am modelling the bending fail
ure of ice in the bow area and also the splitting of floes
that interact with the floater,” says Lu.
Bending Failure
Lu is striving to model the bending failure of ice as a
progressive failure process. He has initially created
several different numerical methods to model the frac
ture and fragmentation process (see Fig. 10).
Based on the experiments he conducted at the Ham
burg Ship Model Basin (HSVA) in April 2012 (further
details and visual aids under Associated Projects on
pages 44-47), he proposed a theoretical model to cap
ture the important interaction mechanisms as shown
in Fig. 11. In this experimental and theoretical model
Floating Structures in Ice
Remote and deep water hydrocarbon fields require floating structures to
facilitate both drilling and production.
Fig. 8. Splitting of ice floes by the icebreaker Oden (OATRC2012)
Fig. 9. Waterline processes (splitting, bending and venti-
lation effects).