Item: Measuring the Mechanical Properties of Snow Relevant For Dry-Snow Slab Avalanche Release Using Particle Tracking Velocimetry
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Title: Measuring the Mechanical Properties of Snow Relevant For Dry-Snow Slab Avalanche Release Using Particle Tracking Velocimetry
Proceedings: International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA
Authors:
- Alec van Herwijnen [ SLF, Davos Dorf, Switzerland ]
- Ned Bair [ Earth Research Institute, University of California, Santa Barbara, CA, USA ]
- Karl Birkeland [ USDA Forest Service National Avalanche Center, Bozeman, MT, USA ]
- Ben Reuter [ SLF, Davos Dorf, Switzerland ]
- Ron Simenhois [ Coeur Alaska, Juneau, AK, USA ]
- Bruce Jamieson [ Snowline Associates Ltd., Calgary, AB, Canada ]
- Jürg Schweizer [ SLF, Davos Dorf, Switzerland ]
Date: 2016-10-02
Abstract: Particle tracking velocimetry (PTV) is a measurement technique widely used to determine displacement and velocity fields from video recordings. It is largely nonintrusive and capable of simultaneously measuring the state of deformation over an entire cross section of a sample. PTV has been used in field and laboratory experiments since the mid-1990s to study snow deformation and fracture. Initial studies focused primarily on documenting weak layer collapse and crack propagation velocities. However, recent technological and computational advances allow researchers to determine essential mechanical properties relevant to the processes involved in snow slab avalanche release. Indeed, PTV has been used to estimate the effective elastic modulus of the slab, weak layer specific fracture energy, crack propagation distance and speed, and the friction between the slab and the bed surface after fracture. In this contribution, we will give an overview of over 500 field experiments performed in Canada, USA, and Switzerland over the last 15 years, with an emphasis on relating derived snow mechanical properties to commonly observed snow cover characteristics. For instance, our results suggest that crack propagation speed, which increases with slab density, strongly correlates with crack propagation distance. Furthermore, crack face friction, which determines the critical slope angle at which an avalanche releases, is affected by the hardness differences across the weak layer. While PTV has improved our understanding of the fundamental processes involved in snow fracture, we will also highlight topics that have received little attention to date.
Object ID: ISSW16_O17.03.pdf
Language of Article: English
Presenter(s):
Keywords: snow mechanical properties, avalanche release, Particle Tracking Velocimetry, snow stability
Page Number(s): 397-404
Subjects: snow mechanics Particle Tracking Velocimetry avalanche release
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