The Creep of Snow under Combined Stress

Abstract

Unclassified Report Laboratory experiments on the creep of sifted snow under uniaxial, hydrostatic, and confined-side compressive stresses are described, and the re sults are discussed on the basis of an additive theory for combined stresses. Stress (4-40 psi) and temperature (-3.6C to-13.6C) dependence was investigated for 35 samples (initial density =0.4 g/ cm3) subjected to uniaxial and hydrostatic stress for 200-sec time increments. Another series of 104 samples (initial densities 0.36-0.63) was subjected to uniaxial, hydrostatic, and confined-side compres sive stresses until an arbitrary change in density was reached. In all cases the applied stress ultimately became a shear stress acting between grains, the open structure reacting differently to (over) combined stresses and separate uniaxial stresses. An activation energy of 13,400 cal/mol was obtained from the first group of tests.

Flow simulation of a firn-covered cold glacier

“…In order to assess the influence of a and b on the simulation, another set of functions, noted a2 and b 2 , was obtained by analysing the experimental results of Landauer (1957) through Duva and Crow's (1994) modeL Landauer performed a number of creep tests on snow, under isotropic compression, uniaxial compression and compression with lateral confinement, and found that for relative densities D between 0.39 and 0.69, and loads between 0.027 and 0.27 MPa, the appropriate value of exponent n was 3. The corresponding values of a and b are shown in Figure 2a and b, as well as the continuous set of functions which fit these values, given by:…”

“…Model parameters a (a) and b (b) vs relative density D. Solid lines showDuva and Crow's (1994) originalfunctions (ao, bo), andfunctions(aI, bIJ, (a2, b 2 ) used in this study. Symbols show the values corresponding to Site 2 data and toLandauer's (1957) creep tests (u, uniaxial compression; C, confined compression; 1, isotropic compression).…”

Snow Forces

“…In this case obviously only the first of the above-mentioned methods will furnish reliable results. Landauer (1957) first recognized that the cross-section numbers resulting from the second method and the use of Equation (6) generally over-estimates the real coefficients ζ . His results using method 1 and 2 are represented in Figure 8.…”

Shear Test on Snow Explained by Fast Metamorphism

“…However to characterize it is often very difficult. Density and temperature may be of considerable influence, but cannot give a good indication of the state of the bond system, and for this reason results which did not consider the bond system differ widely (Landauer, 1957; Yosida and others, 1955–58; Ramseier and Pavlak, 1964; Feldt and Ballard, 1965; Ballard and Feldt, 1965; Kinosita, 1967; Shinojima, 1967; Mellor and Smith, 1967; Keeler, 1969; Yong and Fukue, 1977).…”