Influence of Microstructure on Mechanical Properties of Snow

Abstract

Snow, being composed of ice grains of varying shapes, sizes, orientations, etc., has been treated as a particulate material. The mechanical properties of snow have been described in terms of microstructural parameters. A set of variables, which characterise the microstructure of snow at the granular level, has been chosen and quantified following the techniques of quantitative stereology for section plane. The data of quasi-static tests, e.g. constant strain-rate creep tests, have been analysed to determine the Young's modulus and compactive viscosity and the same have been correlated with the microstructural parameters. Inspite of scatter, definite trends are discernible. Considering the fact that deformation of snow is associated with translation and rotation of constituent grains in such a way as to attain the most stable configuration, the concept of fabric reconstruction, which is characterised by the concentration of normals (to the tangent plane at the point of grain contact) in the direction of the applied load, has been examined. The results demonstrated the occurrence of fabric reconstruction during the process of deformation. Finally, a dimensionless quantity, called the microstructural index (I), has been proposed to adequately represent the influence of microstructure.