Ice-sheet flow conditions deduced from mechanical tests of ice core
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Ice-sheet flow conditions deduced from mechanical tests of ice core. / Miyamoto, Atsushi; Narita, Hideki; Hondoh, Takeo; Shoji, Hitoshi; Kawada, Kunio; Watanabe, Okitsugu; Dahl-Jensen, Dorthe; Gundestrup, Niels Steen; Clausen, Henrik Brink; Duval, Paul.
In: Annals of Glaciology, Vol. 29, No. 1, 1999, p. 179-183.Research output: Contribution to journal › Journal article › Research › peer-review
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TY - JOUR
T1 - Ice-sheet flow conditions deduced from mechanical tests of ice core
AU - Miyamoto, Atsushi
AU - Narita, Hideki
AU - Hondoh, Takeo
AU - Shoji, Hitoshi
AU - Kawada, Kunio
AU - Watanabe, Okitsugu
AU - Dahl-Jensen, Dorthe
AU - Gundestrup, Niels Steen
AU - Clausen, Henrik Brink
AU - Duval, Paul
PY - 1999
Y1 - 1999
N2 - Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate (type A) and constant load (type B). Fifty-four uniaxial-compression test specimens from 1327-2922 m were selected. Each test specimen (25 mm × 25 mm × 90 mm) was prepared with its uniaxial stress axis inclined 45° from the core axis in order to examine the flow behavior of strong single-maximum ice-core samples with basal planes parallel to the horizontal plane of the ice sheet. The ice-flow enhancement factors show a gradual increase with depth down to approximately 2000 m. These results can be interpreted in terms of an increase in the fourth-order Schmid factor. Below 2000 m depth, the flow-enhancement factor increases to about 20-30 with a relatively high variability. When the Schmid factor was > 0.46, the enhancement factor obtained was higher than expected from the c-axis concentrations measured. The higher values of flow-enhancement factor were obtained from specimens with a cloudy band structure. It was revealed that cloudy bands affect ice-deformation processes, but the details remain unclear. Udgivelsesdato: June
AB - Uniaxial compression tests were performed on samples of the Greenland Ice Core Project (GRIP) deep ice core, both in the field and later in a cold-room laboratory, in order to understand the ice-flow behavior of large ice sheets. Experiments were conducted under conditions of constant strain rate (type A) and constant load (type B). Fifty-four uniaxial-compression test specimens from 1327-2922 m were selected. Each test specimen (25 mm × 25 mm × 90 mm) was prepared with its uniaxial stress axis inclined 45° from the core axis in order to examine the flow behavior of strong single-maximum ice-core samples with basal planes parallel to the horizontal plane of the ice sheet. The ice-flow enhancement factors show a gradual increase with depth down to approximately 2000 m. These results can be interpreted in terms of an increase in the fourth-order Schmid factor. Below 2000 m depth, the flow-enhancement factor increases to about 20-30 with a relatively high variability. When the Schmid factor was > 0.46, the enhancement factor obtained was higher than expected from the c-axis concentrations measured. The higher values of flow-enhancement factor were obtained from specimens with a cloudy band structure. It was revealed that cloudy bands affect ice-deformation processes, but the details remain unclear. Udgivelsesdato: June
U2 - 10.3189/172756499781820950
DO - 10.3189/172756499781820950
M3 - Journal article
VL - 29
SP - 179
EP - 183
JO - Annals of Glaciology
JF - Annals of Glaciology
SN - 0260-3055
IS - 1
ER -
ID: 187070