Item: On How to Measure Snow Mechanical Properties Relevant to Slab Avalanche Release
-
-
Title: On How to Measure Snow Mechanical Properties Relevant to Slab Avalanche Release
Proceedings: International Snow Science Workshop Grenoble – Chamonix Mont-Blanc - October 07-11, 2013
Authors:
- Benjamin Reuter [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Martin Proksch [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Henning Loewe [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Alec van Herwijnen [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Jürg Schweizer [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
Date: 2013-10-07
Abstract: The release of a slab avalanche is preceded by a sequence of fractures. The main material properties relevant for the fracture processes are the specific fracture energy of the weak layer as well as the effective elastic modulus and the density of the overlying slab layers. Recent advances in measurement techniques and data processing now allow us to objectively determine these snowpack properties. At the micro-scale, the three dimensional structure of snow samples is obtained from snow micro-tomography (μCT). By modelling the mechanical behaviour based on the snow microstructure, the elastic properties are derived. At the macro-scale, fracture mechanical field tests with particle tracking velocimetry (PTV) allow observing the in-situ fracture behaviour. Specific fracture energy and slab effective elastic modulus are derived from PTV measurement by fitting an analytical beam equation to the observed deformation field. High resolution snow stratigraphy data are obtained from field measurements using the snow micro-penetrometer (SMP). The SMP bridges the gap between both scales since it provides micro-structural information for all layers within the snow cover. Using these three techniques, we compiled a dataset of the mentioned material properties. In many cases we were able to apply at least two of the methods to the same sample. The results show that the different measurement and analysis techniques provide comparable values for fracture energy, effective elastic modulus as well as density, even though the measurements were performed at different scales. With reliable methods to determine the key parameters describing the fracture process now being available, snow instability modelling based on either snow cover simulations or spatial field measurements can be envisaged.
Object ID: ISSW13_paper_O2-02.pdf
Language of Article: English
Presenter(s): Unknown
Keywords: snow microstructure, snow mechanical properties, snow fracture, snow stability evaluation, avalanche release
Page Number(s): 007-011
Subjects: slab avalanche avalanche release fracture mechanics
-