Analysis of sliding failure of the Viviers-Basques' (France) jointed rock cliff

The deterioration of coastal cliffs, such as the Viviers-Basques’, is more and more considered in France because of potential risks. In order to analyze the influence of the mechanical and hydraulic properties on the jointed rock mass behaviour, this cliff has been modelled using a distinct elements method. For this purpose, we have considered the geology, the geometry (lithology, jointing) and hydrogeology of the rock mass established thanks to in-situ measurements. According to in-situ observations and to kinematic analysis, the failure type is plane slide. Geomechanical characterization of the rock mass has been done through the GSI. Finally a two dimensions model has been realized with UDEC. The simulation illustrates that the more deteriorated the mechanical properties are, the less the water level needs to be high to collapse the cliff. Failure expands from the bottom to the top of the cliff. It also seems to show that the failure of the top beds is indicating a more extensive phenomenon.