Contribution à l'analyse de la déformation et de la rupture des grands versants rocheux en terrain cristallophyllien

Abstract

In mountainous regions, the study of the stability of rock slopes is of major importance for land management and safety of populations. The monitoring of several unstable alpine slopes has shown the existence of continuous movements with periods of acceleration, but the interpretation of these measurements is still difficult and makes any longer time prediction very uncertain. Three unstable slopes in the Alps, chosen in foliated metamorphic rocks are presented to illustrate the different deformation mechanisms that can be encountered. In particular, we present an analysis of the slope movement at Séchilienne, which is a case of gravity deformation associated with internal rupture of the rocks. The common characteristic of all of these mechanisms is the emergence of an important spatial complexity in the displacements and the stress distribution. This complexity, combined with local ruptures spread in time, allows one to account for the field observations and to integrate them in geomechanical models at the scale of the slope.