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Etude des éboulements rocheux par méthodes géophysiques

Abstract : Rock falls pose critical problems to risk management, due to the suddenness of the phenomena and the lack of precursors. Detection of unstable rock mass, evaluation of stability and comprehension of dynamic phenomenon are major elements in order to evaluate the rock falls potential hazard. In first step, the Ground Penetrating Radar allowed the 3D fractures network to be determined. An inversion strategy for fractures characterization (aperture and filling) is proposed by using the frequencial and angular sensitivity of the reflectivity of the electromagnetic waves with a thin bed approach. This methodology was applied successfully on two different study sites.

In second part, a new seismic magnitude scale was defined, which allowed us to compare and classify ground-motion vibrations. No relation was found between rock-fall parameters (fall height, runout distance, volume, potential energy) and rock-fall seismic magnitudes. On the other hand, the signal duration shows a rough correlation with the potential energy and the runout distance, highlighting the control of the propagation phase on the signal length. The signal analysis suggests the existence of at least two distinct seismic sources: one corresponding to the initial rupture associated with an elastic rebound during the detachment and the other one generated by the rock impact on the slope, whose frequency shape was confirmed by a 2D finite-element simulation.
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https://tel.archives-ouvertes.fr/tel-00195215
Contributor : Jacques Deparis <>
Submitted on : Tuesday, December 11, 2007 - 4:37:26 PM
Last modification on : Thursday, November 19, 2020 - 3:54:28 PM
Long-term archiving on: : Friday, November 25, 2016 - 7:38:21 PM

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  • HAL Id : tel-00195215, version 2

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Jacques Deparis. Etude des éboulements rocheux par méthodes géophysiques. Géophysique [physics.geo-ph]. Université Joseph-Fourier - Grenoble I, 2007. Français. ⟨tel-00195215v2⟩

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