Signatur:
ZSP-202-271
In:
Research report
Beschreibung / Inhaltsverzeichnis:
CONTENTS: Introduction. - Previous work. - Conduct of the research. - Fundamental properties of snow. - Derived properties of snow. - Environmental effects. - Conclusions. - Literature cited. - Abstract.
Beschreibung / Inhaltsverzeichnis:
One of the great deficiencies in snow science is the lack of an analytical framework for much of the snow cycle. Snow research to date has largely consisted of measuring index properties of snow, such as bulk density and snow strength, and correlating them. This is useful, particularly for engineering purposes, but it does not grapple with the basic problem of what fundamental properties of snow determine the magnitude of the index properties and how these properties respond to environmental conditions. This study was an attempt to measure, quantitatively, the fundamental properties of grain size, shape, and fabric (relationship between grains) and relate these to the index or derived properties of bulk density, shear and tensile strength, permeability for air, and the dielectric static permittivity and loss tangent. Despite numerous difficulties in defining fabric and quantifying it, it was possible to show that: 1) snow strength is a function of bond area with a relationship in the low density range that is described by: [Sigma]f = [Sigma]i exp - (0.14nf) where [Sigma]f is failure strength, [Sigma]i is the final strength of ice, and nf is the porosity on the failure surface; and 2) the rate of densification of low density snow can be explained in part by high stress concentrations (on the order of 10^7 dynes /cm^2) at intergranular contacts and by such factors as riming on crystals. The effect of the environmental factors of time, temperature, and gravitational stress is difficult to study in situ because they are not independent variables. However, it appears that their study is simplified when we study the fundamental properties of snow as opposed to index properties.
Materialart:
Schriftenreihen ausleihbar
Seiten:
v, 70 Seiten
,
Illustrationen
Serie:
Research report / Cold Regions Research and Engineering Laboratory, CRREL, US Army Material Command 271
URL:
http://www.worldcat.org/oclc/5325802
Sprache:
Englisch
Zweigbibliothek:
AWI Bibliothek
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