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Mechanical tests of ice core samples from Dome GRIP, Greenland

对格陵兰 Dome GRIP 冰芯样本进行机械测试

基本信息

批准号：
04640412
负责人：
SHOJI Hitoshi
金额：
$ 1.09万
依托单位：
Kitami Institute of Technology (1993)University of Toyama (1992)
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1992
资助国家：
日本
起止时间：
1992 至 1993
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/en/grant/KAKENHI-PROJECT-04640412/
关键词：
Greenland Dome GRIP Ice core Mechanical test

项目摘要

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.

要了解极地大冰块的流动行为，需要研究深层天然冰川冰的力学特性。 1990-92年欧洲科学基金会资助的格陵兰冰芯项目在格陵兰岛Dome GRIP（北纬72ﾟ35'，西经37ﾟ38'）成功获得了一个新的3029米深的冰芯。晶体尺寸测量揭示了与杂质含量和冰温变化相对应的随深度变化的特征。在 770 m 深度以下，晶体的尺寸保持相当恒定。威斯康星冰（深度 1624 米以下）的晶体尺寸要小得多，这可能是由于杂质浓度较高所致。在冰盖底部附近，晶体尺寸的增加可能是由于较高冰温下晶体生长造成的。晶体取向织物测量结果表明，单最大织物随深度增强，尤其是威斯康星州冰中强烈的单最大图案。然而，在冰盖底部附近，织物变成了多极大值图案，表明冰晶在高温下发生了重结晶。单轴压缩试验是在应力轴与冰芯轴倾斜45°的情况下进行的，以使最大分辨剪应力平行于冰芯水平面。结果表明，正如晶体取向织物所预期的那样，冰很容易沿着水平面变形。根据每个冰晶基面滑移的施密德因子对冰样品的强度进行定量解释。这些发现表明，穹顶可以通过底面水平的冰晶流动轻松地将位置调整到新位置。