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Combinaison d'informations ponctuelles et volumiques pour le diagnostic d'ouvrages en terre soumis à des risques hydrauliques

Abstract : The river protection levees represent more than 8 600 km of works on the national territory and are very heterogeneous, because of a construction made from mate- rials encountered nearby as well as their history (breaks and repairs, extensions...). In order to prevent the risk of structural failure, which can lead to catastrophic consequences such as loss of lives and economic disasters, protection levees require special supervision. This surveillance _rst requires visual recognition, in addition to historical and bibliographical research. Recognized methodologies for levee assess- ment also include geophysical and geotechnical survey methods. These two families of methods are complementary but rarely considered jointly. At best, the results obtained by each method are simply overlaid. Geophysical me- thods are non-intrusive and provide physical information on large volumes of soils with high output but with signi_cant potential uncertainties. These uncertainties are due in particular to the integrating and indirect aspects of the methods as well as to the resolution of the intrinsically ill-posed inverse problems. Moreover, the measured physical quantity does not _t into the models of justi_cation of the struc- tures with respect to the modes of rupture. Geotechnical reconnaissance methods, on the other hand, are intrusive and provide more intermittent information but also more accurate and more adapted to the analysis of failure modes. An important issue for the evaluation of _uvial protection levees is to be able to combine acquired geophysical and geotechnical data, while taking into consideration their respective imperfections and spatial distributions. This particular context of natural risk is therefore associated with our ability to characterize an earthen hydraulic structure from at least two survey methods : a geophysical and a geotechnical one. In this thesis work, we propose the use of information fusion models, and we use the theory of belief masses to combine the data from these two families of recognition methods to present a characterization of the levee. We propose here a methodology of combinations of information, resulting from geophysical and geotechnical survey methods, taking into account the speci_cities of each method concerning the associated data imperfection as well as the spatial distribution of the information. This new methodology makes it possible to improve the characterization of geological sets within hydraulic structures and indicate the con_ict level between information sources while associating a con_dence index with the proposed results. These results could have an impact on the optimization of the following survey campaigns (number and positions of the tests to be carried out, according to the location of low con_dence or con_ictual areas). The methodology developed is detailed throughout this manuscript and imple- mented through examples of subsoil sections characterized by synthetic and experi- mental data as well as by a real earthen hydraulic structure.
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Contributor : Theo Dezert <>
Submitted on : Wednesday, January 29, 2020 - 10:51:44 AM
Last modification on : Monday, October 19, 2020 - 11:08:11 AM
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Théo Dezert. Combinaison d'informations ponctuelles et volumiques pour le diagnostic d'ouvrages en terre soumis à des risques hydrauliques. Sciences de l'ingénieur [physics]. Université de Nantes - Faculté des Sciences et Techniques, 2019. Français. ⟨tel-02459100⟩

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