Item: FROM COMPACTION TO FAILURE: CREEP ACCELERATION AND BUCKLE FORMATION IN A GLIDING SNOW BEAM
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Title: FROM COMPACTION TO FAILURE: CREEP ACCELERATION AND BUCKLE FORMATION IN A GLIDING SNOW BEAM
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 ]
- 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 ]
- Alec van Herwijnen [ WSL Institute for Snow and Avalanche Research SLF, Davos, Switzerland ]
- Christophe Ancey [ Environmental Hydraulics Laboratory, Ecole Polytechnique Federale de Lausanne, Lausanne, Switzerland ]
Date: 2026-09-28
Abstract: Glide-snow avalanches are difficult to predict and mitigate and can pose major challenges for the protection of roads, ski resorts, and buildings. They occur when the entire snow cover slowly slides downslope before suddenly releasing as an avalanche. The physical processes involved in the release of glide-snow avalanches remain poorly understood. To investigate snowpack deformation during gliding, we developed a laboratory tilt test under controlled cold-room conditions. A 1.67 m long snow beam rested on a temperature-controlled glass bed tilted at 30°; at the downslope end, an instrumented stop representing the mechanical support of a retention zone recorded the force, while the deformation of the beam side wall was monitored. Each test comprised a cold phase and a warm phase, during which the bed surface was heated above 0 °C to generate liquid water at the snow–glass interface. During the cold phase, most of the slope-parallel load was progressively transferred from the downslope stop to the basal interface. Within minutes of heating, this load returned to the stop and then remained nearly constant until failure. Under this constant load, deformation evolved from secondary to tertiary creep while the beam lost 55 % of its thickness, so that its density increased by a factor of about 2.5. Over the same interval the apparent compressive viscosity decreased by a factor of about 45, suggesting that viscous softening induced by the liquid water dominated the deformation response regardless the elastic stiffening expected from densification. Failure occurred abruptly within one buckle as the apparent strain rate approached 10⁻⁴ s⁻¹. These observations support a release scenario in which loss of basal resistance, progressive rheological softening and localized deformation lead to delayed failure without any increase in external loading. If similar rate-dependent behavior occurs at the slope scale, the temporal acceleration of surface deformation may provide a precursory signal for glide-snow avalanche forecasting.
Object ID: ISSW2026_P1.30.pdf
DOI: https://doi.org/10.15788/1790098767
Language of Article: English
Presenter(s): Grégoire Bobillier
Keywords: Glide-snow avalanche release, tilt test, basal detachment
Page Number(s): 995 - 1000
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