2004 Fiscal Year Final Research Report Summary
Experimental study on ice-on-ice friction and compressive properties of high-density snow
| Project/Area Number |
14390002
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| Research Category |
Grant-in-Aid for Scientific Research (B)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
広領域
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| Research Institution | Hokkaido University |
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Principal Investigator |
ARAKAWA Masahiko Hokkaido University, Inst.Low Temp.Scie., Inst., 低温科学研究所, 助手 (10222738)
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| Co-Investigator(Kenkyū-buntansha) |
NISHIMURA Kouichi National research institute for earth science and disaster prevention, Nagaoka Institute of snow and ice studies, Chief scientist, 長岡雪氷防災研究所, 主任研究員 (10180639)
TAKEI Iwao Hokuriku University, Faculty of Pharmaceutical Sciences, Inst., 薬学部, 講師 (70247477)
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| Project Period (FY) |
2002 – 2004
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| Keywords | high-density snow / granular flow / friction coefficient / destructive deformation / plastic deformation / rheology / non-neutonian fluid / singing snow |
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| Research Abstract |
Friction coefficient of ice changes with the temperature and the relative velocity. So, we have studied the effect of friction coefficient on the snow drag force. The drag force exerted by indentation has been measured below the density of 400kg/m^3. However, the drag force generated in the high-density snow (>400kg/m^3) is now important for the snow debris of avalanche, compressed snow on the road, and icy satellites. Therefore, we made indentation tests to clarify the mechanical behavior of the high-density snow and measured the drag force generated by ice granular flow to study the relationship between the ice friction coefficient and the snow drag force. Snow drag force was measured by using cylinder set in a various depth at -10℃ for the flow speed from 0.5 to 500mm/s. Thus, we have found that the drag force decreased with increasing the flow velocity. But, the same velocity dependence was not found in the test conducted at -50℃: it was a constant. The velocity dependence of the d
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rag force at -10℃ could be explained by the velocity dependence of the ice friction coefficient. The ice friction coefficient decreases with increasing the velocity because of the frictional melting at the boundary to reduce the friction. Compression measurements were conducted by using a rod to penetrate high-density snow. Two types of deformation were recognized plastic-type and destructive-type deformations. In the plastic-type deformation, the relation between the stress and strain rates was nonlinear, hence, this deformation is not Newtonian and is expressed by a power law. This suggests that in addition to the particle rearrangement operative in low-density snow, plastic-type deformation and destruction of ice particles are also important. The critical penetration speeds between the two deformation types were 0.33-0.83, 0.83-1.67, and 1.67-3.33 mm/ for snow densities of 550, 640, and 730 kg/m^3, respectively. The power increased with density and approached 3, which correspond to that required for penetrating ice. Less
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[Book] 雪と氷の事典2005
Author(s)
(社)日本雪氷学会監修(分担執筆)
Total Pages
760
Publisher
朝倉書店
Description
「研究成果報告書概要(和文)」より
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