A theoretical and field study of load transmission through grounded ice rubble
Oil exploration from artificial Islands in the Beaufort Sea has shown that grounded ice rubble fields often accumulate around such structures, preventing moving ice from acting directly against the structure. A simple, rigid body model, has commonly been used to estimate the load "seen" by...
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| Format: | Thesis |
| Language: | English |
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Memorial University of Newfoundland
1990
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| Online Access: | https://research.library.mun.ca/5377/ https://research.library.mun.ca/5377/1/Marshall_AlfredR.pdf https://research.library.mun.ca/5377/2/Marshall_AlfredR.pdf |
| Summary: | Oil exploration from artificial Islands in the Beaufort Sea has shown that grounded ice rubble fields often accumulate around such structures, preventing moving ice from acting directly against the structure. A simple, rigid body model, has commonly been used to estimate the load "seen" by the structure, with the result that no loading is expected until global rubble sliding occurs. It was realized that such an approach is not entirely realistic and so a collaborative field program was carried out, followed by theoretical modelling. The field work was done at a drilling location in the southern Beaufort Sea on ESSO's Caisson Retained Island (CRI). The three groups involved were ESSO Resources Canada Ltd., National Research Council of Canada (NRC) and Memorial University of Newfoundland (M.U.N.). The M.U.N. data and subsequent theoretical work is presented here, with the ESSO and NRC data summarized in the site description. -- Memorial University collected data from pressure sensor rosettes, a strain array, thermocouple arrays, rubble profiling, and ice property measurements. The most important data came from the pressure sensor rosettes and the thermocouple arrays. These indicated that average sea ice pressures against the rubble reached 350 kPa, and that a substantial and rapidly formed refrozen layer existed within the rubble, with a thickness exceeding 3 m near the rubble field periphery. -- Based on the field measurements, a theoretical model was developed to investigate the role of the rubble refrozen layer in load transmission through rubble. The rubble field was modelled as a system of springs and dampers to represent the elastic, frictional, and viscous stiffness of the various load paths. The deformations and load distributions were calculated using a commercial finite element package called ABAQUS. Each material property was assumed to have a range of values, the limits of which were determined from the literature, theoretical considerations and field measurements. -- The sensitivity of the output to ... |
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