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Localisation de la déformation et fracturation associée. Etude expérimentale et numérique sur des analogues de la lithosphère continentale

Abstract : The study of localisation of deformation in brittle/ductile media aims to understand from a mechanical point of view the development of multi-scales fracture patterns, which are characteristic of intra-continental deformation. Experimental modelling of collision at lithospheric scale allows to reproduce and follow with time the fracturation process. The obtained fault patterns have statistical properties similar to the ones of natural fault patterns. Detailed analysis of deformation and fracture organisation provides meaningful information on the system evolution and on the localisation of deformation at large scale. The deformation in an analogue of continental lithosphere is characterized by three factors: the brittle/ductile coupling G, the Argand number Ar and the boundary conditions. G, bound to brittle/ductile coupling, controls the localisation of deformation. Ar characterizes the role of the gravity forces on the expression of the modes of deformation (compression, strike-slip or extension). The boundary conditions influence the spatial distribution of the deformation modes. Through analysis of the deformation fields, the localisation process is divided in two stages: the pre-localisation stage and the post-localisation stage. The pre-localisation stage corresponds to an increase with time of the average deformation according to a power law, which exponent is independent of the rheology of the media. This stage is characterized by a progressive organisation of the deformation, with an increase of the correlation length. It takes place on a time period that is apparently independent of the rheology and the deformation mode. It ends in the development of the fault pattern. The post-localisation stage is characterized by the organisation of deformation according to scaling laws, which fractal dimension depends on the rheology of the media. Despite the stabilisation of the average deformation and of the correlation length (equal to the system size), the system is still dynamic, as proven by the fluctuations of the active faults mass or of the post-localisation correlation dimension. Since the mechanics of the brittle/ductile coupling cannot be explained by the experiments, numerical simulations have been developed. The role of the ductile media viscosity on the localized or distributed mode of fracturation is particularly studied. Results notably shows that a viscosity variation of one order magnitude is sufficient to observe a transition between the localised fracturing mode and the distributed one.
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https://tel.archives-ouvertes.fr/tel-00009829
Contributor : Alain-Hervé Le Gall <>
Submitted on : Monday, July 25, 2005 - 4:27:33 PM
Last modification on : Thursday, January 14, 2021 - 11:41:14 AM
Long-term archiving on: : Friday, November 25, 2016 - 9:24:48 AM

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  • HAL Id : tel-00009829, version 1

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Sylvie Schueller. Localisation de la déformation et fracturation associée. Etude expérimentale et numérique sur des analogues de la lithosphère continentale. Géomorphologie. Université Rennes 1, 2004. Français. ⟨tel-00009829⟩

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