Item: Field Study on Fracture Propagation in Weak Snowpack Layers
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Title: Field Study on Fracture Propagation in Weak Snowpack Layers
Proceedings: Proceedings Whistler 2008 International Snow Science Workshop September 21-27, 2008
Authors:
- Alec van Herwijnen [ WSL, Swiss Federal Institute for Snow and Avalanche Research SLF Davos, Switzerland ]
- Joachim Heierli [ Centre for Materials Science and Engineering, The University of Edinburgh, Scotland ] [ Institut für Zuverlässigkeit von Bauteilen und Systemen, Universität Karlsruhe, Germany ]
- Jürg Schweizer [ WSL, Swiss Federal Institute for Snow and Av alanche Research SLF Davos, Switzerland ]
Date: 2008-09-22
Abstract: Instabilities in snow slopes generally involve the progressive fracture along a weak snowpack layer. Recent field observations on fractures in weak layers have shown that this process results vertical displacement due to crushing of the weak layer. Long beam specimens containing a natural weak layer were used to study the propagation of fracture. Multiple black markers were inserted in the snow above and below the weak layer. The deformation of the slab during fracture propagation was recorded with a portable digital high speed camera. A technique to reconstruct the trajectories of the markers was developed. This resulted in a detailed visualization of the deformation of the slab during fracture propagation. Results show the propagation of a wave through the slab associated with the collapse of the weak layer. Propagation velocities were relatively constant in the middle of the beam and increased towards the edges. The propagation speed in the middle of the beam was 20 ms-1, in agreement with theoretical predictions of a new theory for fracture propagation in weak snowpack layers.
Language of Article: English
Presenters: Dr. Alec van Herwijnen
Keywords: snow avalanche, avalanche release, fracture mechanics, fracture propagation
Page Number(s): 1
Subjects: fracture mechanics avalanche dynamics
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