International Snow Science Workshop Proceedings - Montana State University Library

Item: GLIDE-SNOW AVALANCHE MECHANICS: VELOCITY-DEPENDENT SNOW-GROUND INTERFACIAL FRICTION

• • Title: GLIDE-SNOW AVALANCHE MECHANICS: VELOCITY-DEPENDENT SNOW-GROUND INTERFACIAL FRICTION

    Proceedings: Proceedings, International Snow Science Workshop, Whistler, BC, Canada, 2026

    Authors:

    • Grégoire Bobillier  [ Environmental Hydraulics Laboratory, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland ]  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Rosa Schnebli  [ Department of Geosciences and Engineering, Delft University of Technology, Delft, Netherlands ]
    • Miguel Cabrera  [ Department of Geosciences and Engineering, Delft University of Technology, Delft, Netherlands ]
    • James Glover  [ Institute for Construction in Alpine Regions (IBAR), University of Applied Sciences Grisons, Chur, Switzerland ]
    • Alec van Herwijnen  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
    • Johan Gaume  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]  [ Climate Change, Extremes, and Natural Hazards in Alpine Regions Research Center CERC, Davos, Switzerland ]  [ Institute for Geotechnical Engineering, ETH Zurich, Switzerland ]
    • Christophe Ancey  [ Environmental Hydraulics Laboratory, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland ]
    • Jürg Schweizer  [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]

    Date: 2026-09-28

    Abstract: Glide-snow avalanches occur when the entire snow cover slowly slides downslope and suddenly releases and forms an avalanche. The physical processes controlling glide-snow avalanche initiation remain poorly understood, making their prediction and mitigation difficult. Although liquid water at the snow-ground interface is recognized as a key precursor of glide-snow avalanche release, its role in controlling snow-ground interfacial friction and glide dynamics remains largely unknown. To investigate how liquid water affects snow-ground interfacial friction, we conducted direct shear tests of snow over a temperature-controlled slate surface across a wide range of normal stresses and shearing velocities. Under dry conditions, the interface exhibited strain-softening behaviour described by a Mohr-Coulomb model with a time-dependent cohesive contribution, while shear velocity had no significant effect. Under wet conditions, the amount of measured liquid water did not systematically affect interfacial shear strength; instead, velocity became the dominant control. Slow sliding involved low friction, whereas faster sliding produced higher peak and residual shear resistance. We describe this behaviour using a velocity-dependent Mohr-Coulomb law. Peak strength increased through both cohesion and friction, whereas during sustained sliding the residual cohesion remained approximately constant and rate strengthening is mainly carried by the frictional term. The kinetic friction angle increased strongly with velocity and approached a plateau above approximately 2 mm s-1. This rate strengthening provides stabilizing feed-back during gliding: a steady sliding velocity can exist when basal resistance balances the driving stress, whereas no equilibrium is possible once the maximum basal resistance is exceeded, leading to accelerated sliding. These results provide a constitutive description of the wet snow-ground interface that can be implemented in slope-scale models of glide-snow avalanche initiation.

    Object ID: ISSW2026_O4.4.pdf

    DOI: https://doi.org/10.15788/1790098593

    Language of Article: English

    Presenter(s): Grégoire Bobillier

    Keywords: glide-snow avalanche, snow-ground interface, rate-dependent friction

    Page Number(s): 1001 - 1005

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