Etude du Rôle des Hétérogénéités Structurales et de l'Altération sur la Déstabilisation des Massifs Rocheux par une Approche Couplée de Modélisation Physique et Numérique

摘要

Gravitational slope failures are common phenomena involving all rock slopes, at various scales. It is widely accepted that different factors exert an influence on those gravitational process. Among these, structural heterogeneities (inherited from the geological history of the massif) and alteration/weathering process are of first order. However, the relative influence of those parameters is still poorly constrained. To tackle this question, a coupled physical and numerical modelling approach has been developed, considering both two and three dimensional models based on two natural examples : the La Clapière landslide (Alpes Maritimes, France) and the 1991 Randa rockslides (Valais, Suitzerland). The first goal of this PhD Thesis was to improve the existing physical modelling technique, on the one hand in order to introduce a wide/realistic number of discontinuities in physical models, and on the other hand to perform 3-D physical models based on realistic topographies (using DTM data). Then a numerical experimental process was carried out in order to study the influence of large scale alteration on gravitational slope failure. Results have shown that faults and joints, affecting rock structures, have a strong influence on gravitational failure kinematics and especially through their geometry, persistence and density. It has also been shown that 3-D topography (of first and second order), and large scale mechanical properties (including alteration process) have a major influence on mobilized volume during slope destabilisation.