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Contribution à l'évaluation de l'aléa éboulement rocheux (rupture)

Abstract : The detection of prospective rock falls and the evaluation of their probability of failure for a given period are a key stage in rock fall hazard assessment.
25 rock falls (25-30 000 m3) occurred in French Subalpine Ranges have been described in details. Typical failure configurations have been identified and can be used for the detection of prospective rock falls. From a statistical analysis of 51 rock falls, we have shown that freeze-thaw cycles represent the main triggering factor.
Back analyses realised with limit equilibrium method and distinct element method have shown that the presence and the extension of rock bridges considerably influence the stability and must be taken into account in hazard evaluation. The cohesion of rock bridges determined by laboratory tests on intact rock specimens must be divided by 3 to account for the analysed failures.
Presently, the evaluation of the failure probability as a function of time is only based on expert judgement. We have proposed and tested different models to assess time to failure, for different processes. Parameter values for sub-critical crack propagation models have been estimated by historic back analyses, using an erosion model to estimate the expectancy of life of rock masses. Laboratory tests are needed for a better estimation. Dissolution rates under rainfall are too small to explain the decrease of rock bridges. Preliminary experiments have shown the influence of freeze/thaw cycles on crack propagation.
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Contributor : Magali Frayssines <>
Submitted on : Tuesday, February 14, 2006 - 2:49:16 PM
Last modification on : Friday, November 6, 2020 - 3:45:17 AM
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  • HAL Id : tel-00011605, version 1




Magali Frayssines. Contribution à l'évaluation de l'aléa éboulement rocheux (rupture). Géologie appliquée. Université Joseph-Fourier - Grenoble I, 2005. Français. ⟨tel-00011605⟩



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