International Snow Science Workshop Proceedings - Montana State University Library

Item: FROM FAILURE TO FRACTURE: FIELD MEASUREMENTS OF STRENGTH AND FRACTURE TOUGHNESS OF BURIED SURFACE HOAR UNDER MIXED-MODE LOADING

• • Title: FROM FAILURE TO FRACTURE: FIELD MEASUREMENTS OF STRENGTH AND FRACTURE TOUGHNESS OF BURIED SURFACE HOAR UNDER MIXED-MODE LOADING

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

    Authors:

    • Melin Walet  [ WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH - 7260 Davos Dorf ]
    • Jakob Schöttner  [ WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH - 7260 Davos Dorf ]
    • Valentin Adam  [ WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH - 7260 Davos Dorf ]  [ Institute for Structural Mechanics and Design, TU Darmstadt, Franziska-Braun-Str. 3, D - 64287 Darmstadt ]
    • Florian Rheinschmidt  [ Chair of Lightweight Design, University of Rostock, Albert-Einstein-Str. 2, D - 18059 Rostock ]
    • Philipp Weißgraeber  [ Chair of Lightweight Design, University of Rostock, Albert-Einstein-Str. 2, D - 18059 Rostock ]
    • Philipp Rosendahl  [ Institute for Structural Mechanics and Design, TU Darmstadt, Franziska-Braun-Str. 3, D - 64287 Darmstadt ]
    • Jürg Schweizer  [ WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH - 7260 Davos Dorf ]
    • Alec van Herwijnen  [ WSL Institute for Snow and Avalanche Research SLF, Flüelastrasse 11, CH - 7260 Davos Dorf ]

    Date: 2026-09-28

    Abstract: Dry-snow slab avalanche release involves failure initiation in a weak layer followed by crack propagation. Weak layer strength describes resistance to failure initiation, whereas fracture toughness describes resistance to crack propagation. Because avalanche release occurs on inclined terrain, both processes generally involve mixed-mode compression and shear loading. Weak layers are known to be weaker in shear than in compression, while recent mixed-mode fracture measurements suggest that fracture toughness may show the opposite trend. Here, we combine two field methods to characterize multiaxial strength and mixed-mode fracture toughness for the same buried surface hoar weak layer. A mobile shear–compression unit (MSCU) was used for strength measurements, and a portable mixed-mode fracture test (MMFT) was used to characterize fracture toughness. For the weak layer investigated here, strength was higher in compression than in shear, whereas fracture toughness was higher in shear loading (mode II) than in compression-dominated loading (closing mode I). These contrasting responses highlight the importance of considering failure initiation and crack propagation separately when characterizing weak layer mechanical behaviour.

    Object ID: ISSW2026_O1.6.pdf

    DOI: https://doi.org/10.15788/1790098482

    Language of Article: English

    Presenter(s): Melin Walet

    Keywords: Weak layers, mixed-mode fracture toughness, multiaxial strength, field experiments, snow mechanics

    Page Number(s): 1488 - 1494

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