Laboratory Tests for Dynamic Ice-Structure Interaction.
Final rept. 13 Jun 78-20 Sep 79,
OULU UNIV (FINLAND)*
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The capabilities of the CRREL test basin to simulate dynamic ice-structure interaction with scale model tests cover the whole range of structures in question. For bottom-founded structure simulation, a test pile was designed so that its stiffness, natural frequencies and modes and damping could be varied. The ice movement against the pile was arranged to have constant acceleration in order to excite different modes with different ice velocities. The flexibility of drive system caused jerking ice movement with low velocities. Analysis of the recorded ice forces and acceleration include the refinement at measured ice forces by eliminating the response of the measuring system itself using dynamic equilibrium or transfer function approach. The frequency contents and the damping of vibrations are analysed using Fourier signal analyser. Scaling laws are discussed and it is observed that full similitude cannot be achieved for both ice interaction force and pile and ice vibrations. Results thus far show similitude with in-field ice force histograms both random and saw-tooth like repetitious ice force fluctuations appear. The change from one interaction mode to the other with increasing drive velocities occurs. With high velocities relatively smooth random ice crushing occurs and in some cases natural modes are stable. The greatest energy content of ice forces does not always appear with the natural frequencies of structure. Author
- Snow, Ice and Permafrost
- Test Facilities, Equipment and Methods