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Déformation et rupture des versants en terrain métamorphique anisotrope. Apport de l' étude des Ruines de Séchilienne.

Abstract : The break or rock slopes is causing major risks in all mountainous regions. The anisotropic metamorphic rocks show all the variety of strain mechanisms, which are analysed in the first part of that work, from European examples. The study of the “Ruines de Sechilienne” case, that mobilises several scientific disciplines and is presented in the second part, shows particular interest because of the phenomenon's complexity and because of the importance of the investigation and monitoring actions realised during one decade (1988-1998). The geological approach permitted a precise description of the slope's structure at various scales. The geo-mechanical approach consisted in elaborating a simplified structural model and testing numerically various hypotheses with the distinct elements methods. This permitted us to propose a strain mechanism qualitatively fitting with the geological observations and the displacements measured. This strain mechanism, controlled by the main pre-existing discontinuities families, induces stress concentrations and tensile stresses that may cause a progressive and non reversible damage of the slope (“progressive break”). Finally, the hydro-geological approach focused on studying the outflow, the temperature, the geo-chemical and isotopic properties of the surface and of the underground water sources, in order to determine their origin and their type of transfer. Coupling these three approaches made it possible to propose a global hydro-mechanical model able to explain the influence of the rain regime on the strain rate of the slope. Two research directions are proposed to investigate the possible break geometry. Nevertheless, forecasting the date of the beak remains out of reach. Finally, the observation of the south slope of la Toura, at Saint-Christophe-en-Oisans, suggests that this “progressive break” mechanism might fit to other slopes than the “Ruines de Sechilienne”
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Submitted on : Thursday, July 15, 2010 - 4:27:02 PM
Last modification on : Friday, November 6, 2020 - 4:13:16 AM
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  • HAL Id : tel-00502785, version 1

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Jean-Marc Vengeon. Déformation et rupture des versants en terrain métamorphique anisotrope. Apport de l' étude des Ruines de Séchilienne.. Sciences de la Terre. Université Joseph-Fourier - Grenoble I, 1998. Français. ⟨tel-00502785⟩

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