1993 Fiscal Year Final Research Report Summary
Mechanical tests of ice core samples from Dome GRIP, Greenland
| Project/Area Number |
04640412
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
気象・海洋・陸水学
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| Research Institution | Kitami Institute of Technology (1993)
University of Toyama (1992) |
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Principal Investigator |
SHOJI Hitoshi Kitami Institute of Technology, Professor, 工学部, 教授 (50201562)
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| Co-Investigator(Kenkyū-buntansha) |
KAWADA Kunio Toyama University, Faculty of Science, Associate Professor, 理学部, 助教授 (20019003)
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| Project Period (FY) |
1992 – 1993
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| Keywords | Greenland / Dome GRIP / Ice core / Mechanical test |
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| Research Abstract |
To understand the flow behavior of large polar ice masses, it is necessary to study the mechanical characteristics of natural glacier ice in the depth. A new 3029 m deep ice core was successfully obtained from Dome GRIP (72ﾟ 35'N, 37ﾟ38'W), Greenland by Greenland icecore Project sponsored by European Science Foundation during the 1990-92 field seasons.
Crystal size measurements reveal characteristic changes with depth corresponding to changes of impurity contents and ice temperature. The crystals maintain fairly constant size below a depth of 770 m. Wisconsin ice (below adepth of 1624 m) shows much smaller crystal size probably due to the higher impurity concentrations. Near the bottom of the ice sheet, crystal size increases possibly resulted from crystal growth under the higher ice temperature.
Results of crystal orientation fabrics measurements show strengthening of single maximum fabrics with depth, especially a strong single maximum pattern in Wisconsin ice. Near the bottom of the ice sheet, however, the fabrics becomes of multi-maximum pattern, suggesting recrystalization of ice crystals under a high temperature.
Uniaxial compression tests was conducted with the stress axis inclined 45ﾟ from the core axis so as to have the maximum resolved shear stress parallel to the horizontal plane of the ice core. The results show that ice is quite easy to deform along the horizontal plane as expected from the crystal orientation fabrics. Quantitative interpretations on the strength of ice samples were made in terms of Schmid Factor for basal plane glide of each ice crystal. These findings suggest that the dome could easily adjust the position to a new location by the flow of ice crystals with basal plane horizontal.
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