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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，必须深入研究天然冰川冰的力学特性。1990 ~ 1992年，欧洲科学基金会格陵兰冰芯计划在格陵兰DomeGRIP（72 ° 35 ′ N，37 ° 38 ′ W）获得了一个新的3029 m深的冰芯，其晶体尺寸随深度的变化反映了冰中杂质含量和温度的变化。晶体在770米以下的深度保持相当恒定的尺寸。威斯康星州冰（低于1624米的深度）显示出小得多的晶体尺寸可能是由于较高的杂质浓度。在冰盖底部附近，晶体尺寸增大可能是由于在较高的冰温下晶体生长的结果.晶体取向组构的测量结果表明，随着深度的增加，单峰组构增强，尤其是在威斯康星州冰中，单峰组构增强.在冰盖底部附近，组构呈多峰型，表明冰晶在高温下发生了再结晶。单轴压缩试验中，应力轴与冰芯轴倾斜45 °，使最大分解剪应力平行于冰芯水平面。结果表明，冰很容易沿水平面沿着变形，这与晶体取向组构的预测一致。根据各冰晶基面滑移的施密德因子，对冰样的强度进行了定量解释。这些结果表明，冰穹可以很容易地通过冰晶的流动调整到一个新的位置与基面水平。