Multi-method analysis of the destabilization of a mechanical lift tower located on a rock glacier in the French Alps

• Published in: Géomorphologie : relief, processus, environnement
• Main Authors: Duvillard, Pierre-Allain, Ravanel, Ludovic, Schoeneich, Philippe, Marcer, Marco, Piard, Jean-François
• 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), Pacte, Laboratoire de sciences sociales (PACTE), Sciences Po Grenoble - Institut d'études politiques de Grenoble (IEPG)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes 2016-2019 (UGA 2016-2019 )
• Format: Article in Journal/Newspaper
• Language: French
• Published: HAL CCSD 2019
• Subjects: permafrost; subsidence; rock glacier; Electrical Resitivity Tomography; French Alps; Ropeway transport systems; Remontées mécaniques; glacier rocheux; tomographie électrique résistive; Alpes françaises; [SDU.STU.GM]Sciences of the Universe [physics]/Earth Sciences/Geomorphology; [SPI.GCIV.IT]Engineering Sciences [physics]/Civil Engineering/Infrastructures de transport; [SPI.GCIV.RISQ]Engineering Sciences [physics]/Civil Engineering/Risques; Pylon; Ice
• Online Access: https://hal.science/hal-02350713; https://hal.science/hal-02350713/document; https://hal.science/hal-02350713/file/Duvillard-et-al_2019_G%C3%A9omorphologie2.pdf; https://doi.org/10.4000/geomorphologie.12945

International audience In the Val Thorens ski resort (Savoie, France), more than 79 infrastructure elements related to ropeway transport systems are located on permafrost. During the last decade, three of them (two top stations and a pylon located around 3,000 m a.s.l.) experienced destabilization which required important adjustment and stabilization work. his study investigates the destabilization of the pylon #2 of the horens funitel that occurred during the Summer 2016. Its foundations were afected by horizontal displacement and subsidence, causing a metric shit of the pylon top with respect to the cable. he pylon was built on a rock glacier which morphology was severely altered by earth work aiming to develop a ski slope. A multidisciplinary analysis was conducted in order to understand the processes that led to the pylon destabilization with a focus on the role of the morphological alterations of anthropogenic origin on the rock glacier dynamic. We used (i) a stratigraphic data analysis from boreholes and (ii) a subsurface analysis based on geophysics (Electrical Resistivity Tomography proiles) to understand the rock glacier internal structure, while (iii) geomorphological surface modiications were investigated by comparing digital terrain models obtained by aerial photogrammetry before and ater the earthwork. his study highlights the preparatory role of the earthwork and a non-control of the surface water low in an ice-rich environment such as a rock glacier. La station de Val horens (Savoie, France) concentre plus de 79 composantes de remontées mécaniques en contexte de permafrost probable. Au cours de la dernière décennie, trois d' entre elles (deux gares amont et un pylône), situées vers 3 000 m d'altitude, ont subi des déstabilisations partielles nécessitant d'importants travaux de confortement et de stabilisation. Cet article documente la déstabilisation du pylône n° 2 du funitel de horens au cours de l' été 2016. Ses fondations ont été afectées par un déplacement horizontal et un afaissement à l' ...