Auscultation et surveillance des perturbations hydromécaniques d'ouvrages souterrains par méthodes ultrasonores :

Abstract : During the excavation of a gallery, whatever the excavation method is, the surrounding rock mass is mechanically disturbed. These distributions can lead to the instability of a part or all of the excavation. In addition, in case of a stock framework, these mechanical changes of the rock state can create preferential ways for the release of the stocked material end side the excavation (nuclear or chemical wastes gas, brine...) up to biosphere. The mechanical characterization of this disturbed zone is then essential to determine the rock capacity to constitute a geological impermeable rock barrier. A set of preliminary experiments has been done on samples of the clay from Bure (Meuse/Haute-Marne) in France where the samples are subject to uniaxial compressive stress and to triaxial compressive stress at 10 MPa confining pressure. During these experiments, some velocity measurements were made into several directions, acoustic emissions monitoring was also performed. The results show that the confining pressure has a strong influence on the P-wave velocity and the threshold of dilatancy. And according to the ray incidence with the lithology, there is a correlation between classical mechanical parameters of damage and P-wave. Therefore, the signal changes in clay are a good indicator of confining and damaging. Therefore, the stake is to determine the nature, the extension, and the change of this disturbed zone. The survey by ultrasonic waves analysis is particularly appropriate for these objectives because it allows us to get knowledge about the zone undisturbed by the boreholes. The main objective of this part is to describe a new in-site experiment (EDZ cut-off) that was realised in the Opalinus Clay in the Mont Terri Rock Laboratory in Switzerland. This experiment includes the use of the seismic imaging method for understanding the evolution of the excavation damaged zone before and after a slot excavation. The velocity before and after the reloading of the slot excavation and the survey during the slot excavation showed a decrease of the P-wave velocity, under the slot floor down to 0.2 m deeper. The reloading clearly improves the P-wave propagation along the sidewall and weakly decreases the same characteristic under the slot. During the all the phases of this thesis the wave attenuation and the number density of cracks were estimated
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Jamil Damaj. Auscultation et surveillance des perturbations hydromécaniques d'ouvrages souterrains par méthodes ultrasonores :. Autre. Institut National Polytechnique de Lorraine, 2006. Français. ⟨NNT : 2006INPL012N⟩. ⟨tel-01752483⟩

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