Shear Test on Snow Explained by Fast Metamorphism

Montmollin, Vincent de

doi:10.3189/s0022143000011898

Cited by 21 publications

(20 citation statements)

References 18 publications

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“…Rotary vane devices consist of two large crossed plates that are inserted into the snowpack (Figure ). The torque required to cause movement of the device is measured using a manual torque wrench [ Perla , ] or by strain gauges coupled to an electric motor responsible for imparting the torque [ DeMontmollin , ]. Rotary vane devices can be used on large snow samples extracted from the snowpack [ Perla et al , ].…”

Section: Instrumentation and Techniquesmentioning

confidence: 99%

Measurement of the physical properties of the snowpack

Kinar

Pomeroy

2015

Reviews of Geophysics

196

202

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This paper reviews measurement techniques and corresponding devices used to determine the physical properties of the seasonal snowpack from distances close to the ground surface. The review is placed in the context of the need for scientific observations of snowpack variables that provide inputs for predictive hydrological models that help to advance scientific understanding of geophysical processes related to snow in the near-surface cryosphere. Many of these devices used to measure snow are invasive and require the snowpack to be disrupted, thereby precluding the possibility for multiple measurements to be made at the same sampling location. Moreover, many devices rely on the use of empirical calibration equations that may not be valid at all geographic locations. The spatial density of observations with most snow measurement devices is often inadequate. There is a need for improved automation of snowpack measurement instrumentation with an emphasis on field-based feedback of measurement validity in lieu of postprocessing of samples or data at a lab or office location. The scientific future of snow measurement instrumentation thereby requires a synthesis between science and engineering principles that takes into consideration geophysics and the physics of device operation.

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Section: Instrumentation and Techniquesmentioning

confidence: 99%

Measurement of the physical properties of the snowpack

Kinar

Pomeroy

2015

Reviews of Geophysics

196

202

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“…Since then, numerous experimental studies investigated the effects of normal load on shear strength of snow and snow weak layers, mainly through shear frame or shear vane tests. Results showing an influence of normal stress on various snow types were reported by Roch (1966), DeMontmollin (1978DeMontmollin ( , 1982, McClung (1977), Perla and Beck (1983) and Navarre et al (1992). Jamieson and Johnston (1998) reported similar influence on non-persistent weak layers, but found no significant effect on persistent weak layers, thus proposing φ = 0 • .…”

Section: Objectives and Scope Of The Studymentioning

confidence: 67%

Evaluating snow weak-layer failure parameters through inverse finite element modelling of shaking-platform experiments

Podolskiy¹,

Chambon²,

Naaïm³

et al. 2015

Nat. Hazards Earth Syst. Sci.

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Abstract. Snowpack weak layers may fail due to excess stresses of various natures, caused by snowfall, skiers, explosions or strong ground motion due to earthquakes, and lead to snow avalanches. This research presents a numerical model describing the failure of "sandwich" snow samples subjected to shaking. The finite element model treats weak layers as interfaces with variable mechanical parameters. This approach is validated by reproducing cyclic loading snow fracture experiments. The model evaluation revealed that the Mohr-Coulomb failure criterion, governed by cohesion and friction angle, was adequate to describe the experiments. The model showed the complex, non-homogeneous stress evolution within the snow samples and especially the importance of tension on fracture initiation at the edges of the weak layer, caused by dynamic stresses due to shaking. Accordingly, a simplified analytical solution, ignoring the inhomogeneity of tangential and normal stresses along the failure plane, may incorrectly estimate the shear strength of the weak layers. The values for "best fit" cohesion and friction angle were ≈ 1.6 kPa and 22.5-60 • . These may constitute valuable first approximations in mechanical models used for avalanche forecasting.

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“…Some problems do exist with the shear frame method, such as collapse of low-density snow layers after frame insertion, sample plucking instead of shear, and the inability to sample weak layers with thicknesses less than the shear frame. Despite these problems the technique is considered a suitable one for shear-strength determination and has been used widely by other workers (perla 1977;McClung 1977;Montmollin 1982;Perla et al 1982;.…”

Section: Data Collection and Analysis Methodsmentioning

confidence: 99%

Snowpack structure and avalanching, Craigieburn Range, New Zealand

McGregor¹

1990

New Zealand Journal of Geology and Geophysics

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A study of the seasonal development of the snowpack at 1700 m elevation in the Craigiebum Range, New Zealand, has revealed three phases of snowpack development. . This phased development is considered in relation to snow avalanching. Analysis of a short period of continuous snowpack temperature gradient data has shown that temperature gradients exceed those generally required for recrystallisation processes, as evidenced by the common occurrence of temperature gradient forms in the snowpack. Partially metamorphosed new snow, especially clusters of rimed needles, and snow in the early stages of temperature gradient metamorphism, are weak in shear and frequently appear in avalanche sliding layers. Weak snowpack stratigraphies resemble those found for Northern Hemisphere inland-continental and coastal-maritime snow climates. Three categories of potential sliding layers for avalanche release are suggested. These are: (1) weaknesses in new snow stratigraphy, (2) weaknesses at old snow surfaces, and (3) weaknesses in temperature gradient layers.

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Shear Test on Snow Explained by Fast Metamorphism

Cited by 21 publications

References 18 publications

Measurement of the physical properties of the snowpack

Measurement of the physical properties of the snowpack

Evaluating snow weak-layer failure parameters through inverse finite element modelling of shaking-platform experiments

Snowpack structure and avalanching, Craigieburn Range, New Zealand

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