Thermal effects on rock slopes : case study of the Rochers de Valabres" slope (France)

International audienceThe causes of slope movements are multiple, varied and act at different spatial and temporal scales. Among such causes, temperature fluctuations are sometimes mentioned as a preparatory factor for rock-falls. Yet measurements of this parameter or of its consequences on deformation and stability are rare. After presenting an analytical computation of the effect of surface temperature fluctuations to derive an order of magnitude of both temperature decrease and deformation variation with depth, the paper will focus on the case study of the "Rochers de Valabres" slope (Southern French Alps). Several field investigations and measurements have been conducted at this site to improve characterization of the thermal effects. Surface measurements using topographic devices will be discussed first. Due to technical limitations and the uncertainties raised by this measurement approach, an alternative internal temperature and strain monitoring device was installed to measure temperatures and strains at depth. Initial results from this effort indicate measurable, but rather intricate, thermo-mechanical phenomena which raised the issue of anisotropic behaviour, more realistic thermal boundary conditions and 3D setup