International Snow Science Workshop Proceedings - Montana State University Library

Item: Modelling the propagation saw test with discrete elements

• • Title: Modelling the propagation saw test with discrete elements

    Proceedings: International Snow Science Workshop Proceedings 2018, Innsbruck, Austria

    Authors:

    • Grégoire Bobillier  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Johan Gaume  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]  [ EPFL Swiss Federal Institute of Technology, School of Architecture, Civil and Environmental Engineering, Lausanne, Switzerland ]
    • Alec van Herwijnen  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Jürg Dual  [ Institute for Mechanical Systems, ETH Zurich, Zurich, Switzerland ]
    • Jürg Schweizer  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]

    Date: 2018-10-07

    Abstract: Dry-snow slab avalanche release is a multi-scale fracture process. It starts with the formation of a localized failure in a highly porous weak snow layer underlying a cohesive snow slab, followed by rapid crack propagation within the weak layer and finally a tensile fracture through the slab leading to its detachment. About 15 years ago, the propagation saw test (PST) was developed, a fracture mechanical field test that provides information on crack propagation propensity in weak snowpack layers. It has become a valuable research tool to investigate processes involved in crack propagation. While this has led to a better understanding of the onset of crack propagation, much less is known about the ensuing propagation dynamics. To analyze the dynamics of propagating cracks, we therefore modeled a three-dimensional PST with the discrete element method (DEM). Using cohesive ballistic deposition, we created a highly porous, anisotropic and brittle weak layer covered by a dense cohesive and isotropic snow slab. By tuning the contact law parameters between particles, we obtained realistic macroscopic behavior of snow deformation for the slab and the weak layer. We then simulated PSTs by cutting the weak layer with a numerical snow saw. The simulations reproduced the dynamics of crack propagation as observed in the field. Our results highlight the influence of the mechanical properties of the slab and weak layer on the stress distribution during crack propagation, the propagation distance before fracture arrest and the propagation speed.

    Object ID: ISSW2018_P10.23.pdf

    Language of Article: English

    Presenter(s):

    Keywords: Dry-snow slab avalanche, discrete element method, crack propagation

    Page Number(s): 976-980

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