Thermomechanical evolution of the movement of 'Séchilienne' since the last quaternary glacial phase

• Main Author: Lebrouc, Vincent
• Other Authors: Institut des Sciences de la Terre (ISTerre), Centre National de la Recherche Scientifique (CNRS)-PRES Université de Grenoble-Université Joseph Fourier - Grenoble 1 (UJF)-Institut Français des Sciences et Technologies des Transports, de l'Aménagement et des Réseaux (IFSTTAR)-Institut national des sciences de l'Univers (INSU - CNRS)-Institut de recherche pour le développement IRD : UR219-Université Savoie Mont Blanc (USMB Université de Savoie Université de Chambéry ), Université de Grenoble, Laurent Baillet
• Format: Doctoral or Postdoctoral Thesis
• Language: French
• Published: HAL CCSD 2013
• Subjects: Séchilienne landslide; Quaternary glacial phase; Cosmic Ray Exposure method; Structural analysis; Distinct and Finite element methods; Thermo-hydro-mechanic modeling; Glissement de Séchilienne; Phase glaciaire quaternaire; Méthode de datation cosmogénique; Analyse structurale; Méthodes des éléments finis et distincts; Modélisation thermo-hydro-mécanique; [SDU.STU]Sciences of the Universe [physics]/Earth Sciences; Ice; permafrost
• Online Access: https://tel.archives-ouvertes.fr/tel-01548332; https://tel.archives-ouvertes.fr/tel-01548332/document; https://tel.archives-ouvertes.fr/tel-01548332/file/LEBROUC_2013-archivage.pdf

The Sechilienne landslide is located thirty kilometers at the Southeast of Grenoble on the Southern edge of the massif of Belledonne. It affects the rock slope on the right bank of the Romanche alpine valley shaped by many cycles of glaciation and deglaciation and which was completely covered by the glacier during the last glacial phase. The oversteepening of the slopes and the deepening of the foot of the slope associated with the phenomenon of debutressing affecting the slope and corresponding to the lateral stress release resulting from ice melting would be so predominant factors in the initiation and development of the Sechilienne landslide. However the recent temporal constraints obtained on the scarp showed a delayed motion relative to the initiation and deglaciation suggest initiation during the Holocene climatic Optimum after a sudden climate change. The initiation and evolution of large movements of rock slopes in mountainous area may be the result of the contribution of different geological factors (fracturing , lithology or tectonic regime) , geomorphology (relief, slope) but also external forcing factors such as earthquakes , permafrost , hydrological changes , the glacier disappearance or climatic effects. These factors are all potentially active in the Sechilienne landslide, so the identification of factors controlling the initiation and development of the movement and which can explain the delay observed between deglaciation and the initiation of movement is tricky.Therefore, we conducted a multidisciplinary study from (1) geophysical data and laboratory tests to determine the depth limits of the mass movement and to assess the volume and the breakdown state, (2) an analysis of the detailed structures of the slope at the surface and in depth to identify the origin of the observed fractures and also their role in the control of the movement (3) a geomorphological analysis of objects on the surface of the slope to discretize , to identify and to select the glacial and gravitational structures on ...