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Three-dimensional Yield Criterion of C-[phi] Material
A general three-dimensional yield criterion of an ideal soil, called c-phi material, is determined that can coincide with the Shield yield criterion and the Drucker-Prager yield criterion by giving appropriate values to the parameters contained. When expressed on an octahedral plane in the principal-stress space, the yield criterion is represented by a hexagon of curved sides formed of conic sections. The geometric relationships satisfied by a family of curved hexagons are investigated. (Author).
Considerations of the Strength of Snow
A mathematical model is presented for the number and size of bonds intersected by a potential failure surface which is age hardening at a constant porosity.
An Approach to the Consolidation of Snow
A consolidation theory is developed for an age-hardened snow under uniaxial stress in the porosity range of 35 to 55% by considering one mechanism, viz., viscous flow of interparticle bonds. For a uniaxial stress sigma, the differential equation for porosity n in terms of time t is shown to be 1/(1-n) dn/dt = nu sigma n/eta (1-an) where a and nu are structural parameters and eta is the coefficient of viscosity of ice. Comparison of this equation and the integrated form with existing data predicts consistent and reasonable values for a. The predicted values of eta/nu range from 0.01 to 100 times the published values for eta, which may indicate that nu, and hence the consolidation rate, is greatly affected by the diagenetic history of the snow and the conditions of experimentation. (Author).
Self-diffusion in Ice Single Crystals
Measurements of the diffusion constants in single crystals of ice in directions parallel and perpendicular to the c-axis are described. The anisotropy of activation energy was obtained. The higher activation energy perpendicular to the c-axis indicates the free interstitial molecular jump mechanism for diffusion in ice. (Author).
Technical Report
None
Strength Studies of Snow
Strength measurements were made on some 650 samples of homogeneous snow prepared under controlled conditions, primarily to investigate the effect of temperature variation. Comparative measurements were made on ice and frozen sand, and the variation of ram hardness with temperature was examined. The results are discussed in terms of surface chemistry effects at crystal boundaries. The inadequacy of density measurements for describing grain structure is discussed.
