International Snow Science Workshop Proceedings - Montana State University Library

Item: Critical Length for the Onset of Crack Propagation in Snow: Reconciling Shear and Collapse

• • Title: Critical Length for the Onset of Crack Propagation in Snow: Reconciling Shear and Collapse

    Proceedings: International Snow Science Workshop 2016 Proceedings, Breckenridge, CO, USA

    Authors:

    • Johan Gaume  [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]  [ EPFL – Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland ]
    • Alec van Herwijnen  [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]
    • Guillaume Chambon  [ Université Grenoble Alpes, IRSTEA, UR ETGR, Grenoble, France ]
    • Nander Wever  [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]  [ EPFL – Ecole Polytechnique Fédérale de Lausanne, Lausanne, Switzerland ]
    • Jürg Schweizer  [ WSL Institute for Snow and Avalanche Research SLF, Davos Dorf, Switzerland ]

    Date: 2016-10-02

    Abstract: The failure of a weak snow layer buried below cohesive slab layers is a necessary, but insufficient condition for the release of a dry-snow slab avalanche. The size of the crack in the weak layer must also exceed a critical length to propagate over a wide surface. In contrast to classical shear-based approaches, the anticrack model accounts for weak layer collapse and allows to better explain typical observations of remote triggering from flat areas. However, the latter model predicts that the critical length for crack propagation is independent of slope angle, a rather surprising and counterintuitive result. Our new mechanical model reconciles past approaches by considering for the first time the complex interplay between slab elasticity and the mechanical behavior of the weak layer including its structural collapse. The crack begins to propagate when the stress induced by slab loading and deformation at the crack tip exceeds the limit given by the failure envelope of the weak layer. We were able to reproduce crack propagation on flat terrain and the decrease of the critical length with slope angle observed in numerical experiments. Our new model agreed well with extensive field data of propagation saw tests and can easily be implemented into a numerical snow cover model.

    Object ID: ISSW16_O1.02.pdf

    Language of Article: English

    Presenter(s):

    Keywords: Snow avalanche, crack propagation, critical length, slope angle, PST, slab, weak layer

    Page Number(s): 12-16

    Subjects: Snow avalanche crack propagation critical length

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