Characterizing the microstructural and micromechanical properties of snow

Abstract

ABSTRACT:A micropenetrometer has been developed that produces snow grain bond ruptures at the microstructural level and provides a unique signal for different snow types . A micromechanical theory of penetration has been developed and used to recover microstructural and micromechanical parameters for different snow types from the penetration force-distance signal. These parameters are the microstructural element dimension, the mean grain size, the critical microstructural deflection at rupture and the microstructural coefficient of elastic restitution. Additional derived mechanical properties include the compression strength and elastic modulus of microstructural elements and continuum scale volumes of snow. Analysis of the forcedistance signal from a Monte Carlo simulation of micropenetration indicates that microstructural and micromechanical parameters may be recovered with an accuracy of better than 5% when spatial and force resolutions are high and the penetrometer tip area is of similar size to the structure dimension.

Measurement of mechanical properties of snow for simulation of skiing

“…For instance, Brown (1980) investigated the snow reaction forces of the neck bindings between snow grains of sintered snow. Johnson and Schneebeli (1999) modeled the penetration force as F ¼ Nf with N the number and f the contribution of each intact microstructural element. Both works support the hypothesis that the snow reaction force against compression is proportional to its volume change.…”

“…Johnson and Schneebeli (1999) related the overall reaction force to micromechanical parameters of the snow. In particular, they modeled the penetration force as F ¼ Nf , with N the number of bonds between the snow particles and f the contribution of each element.…”

A new index combining weak layer and slab properties for snow instability prediction

“…It provides a penetration resistance (force)-depth signal that includes micro-structural information (Johnson and Schneebeli, 1999;Marshall and Johnson, 2009). Mechanical properties can be derived from the three basic micro-structural parameters: element length (L), deflection at rupture (δ) and rupture force (f ).…”

Cone penetration testing (CPT) in Antarctic firn: an introduction to interpretation

“…From the graph it may appear that large-plate data are not recorded until a depth of 0.14 m; however, inspection of the raw data suggests that fluctuating resistance of $5 to 10 kPa was measured at this time; whether this is a true representation of resistance at this shallow depth is not known. Kinosita (1964) and Johnson and Schneebeli (1999) have shown that variations in cone shape affect measured resistance values, both in snow and soils. In order to verify this phenomenon, some tests were conducted with a flat plate of identical diameter to the standard 608 cone; no other cone shapes were used.…”

“…Fukue, 1977) supports this. Penetrometer size affects measured stress in soils (Whiteley and Dexter, 1981), and Johnson and Schneebeli (1999) modelled size effects in granular materials, so it is probable that both cone size and shape will affect measured stress in snow.…”