Mapping release and propagation areas of permafrost-related rock slope failures in the French Alps: A new methodological approach at regional scale

• Published in: Geomorphology
• Main Authors: Cathala, Maëva, Magnin, Florence, Ravanel, Ludovic, Dorren, Luuk, Zuanon, Nicolas, Berger, Frédéric, Bourrier, Franck, Deline, Philip
• Other Authors: Environnements, Dynamiques et Territoires de Montagne (EDYTEM), Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry )-Centre National de la Recherche Scientifique (CNRS)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG), Alpes Ingé SARL, Haute école des sciences agronomiques, forestières et alimentaires (HAFL), A2 Photonic Sensors (A2PS), Laboratoire des EcoSystèmes et des Sociétés en Montagne (UR LESSEM), Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)-Université Grenoble Alpes (UGA), Institut des Géosciences de l’Environnement (IGE), Institut de Recherche pour le Développement (IRD)-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Observatoire des Sciences de l'Univers de Grenoble (Fédération OSUG)-Université Grenoble Alpes (UGA)-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP), Université Grenoble Alpes (UGA), The RockTheAlps database is funded by the European Regional Development Fund, Alpine Space Program, Project “ROCKtheALPS”.
• Format: Article in Journal/Newspaper
• Language: English
• Published: CCSD 2024
• Subjects: Rock slope failure; Permafrost hazard; GIS; Regional mapping; Runout modelling; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques; permafrost
• Online Access: https://hal.science/hal-04388589; https://hal.science/hal-04388589v1/document; https://hal.science/hal-04388589v1/file/cathala_et_al_Geomorphology_HAL.pdf; https://doi.org/10.1016/j.geomorph.2023.109032

International audience The analysis of the influence of the roots on the shear resistance of the soil requires identifying the effect of the different root–soil interaction processes depending on soil and roots properties. For that purpose, a numerical model of direct shear tests of non-rooted and rooted granular soils based on the Discrete Element Method was developed. The soil is modeled as an assembly of locally interacting spheres and the roots are modeled as deformable cylinders in the soil matrix. The model allows accounting for the root tensile loading until breakage, the root bending loading, the root–soil adhesive links until adhesion breakage, the root slippage associated with a frictional resistance at the root–soil interface.The study focuses on identifying the different root–soil interaction mechanisms depending on the soil type. Both frictional and cohesive granular soil types were used in the simulations. The effects of the roots mechanical properties – tensile, bending modulus and root–soil interfacial friction angle – and of the root number were also analyzed for the different soil types.The results first show that the effect of the roots strongly depends on the shear strain for any soil type. For frictional soils, an increasing shear strain induces progressively a pure tensile loading of the roots until slippage of the root–soil interface. For cohesive granular soils, the pure tensile loading of the roots is followed by a progressive breakage of the adhesive root–soil links and by a complete slippage of the roots. The results show that the influence of the root number is significant if the prevailing processes are root tensile loading combined with slippage whereas it is less important if root loading is combined with progressive breakage of the adhesive links for the root configurations explored. Finally, the results show that the shear strain range associated with the different processes strongly depends on the relative rigidities of the roots and soil matrix.The model developed was shown ...