In a few years, safe and definitive solutions should be ready to manage large quantities of high-level radioactive waste. Deep geological repository involving a multi-barrier system constitutes one of the most promising options to isolate such waste from the human environment. In order to provide reasonable assurance of the waste isolation efficiency, it is essential to understand the behaviour of the confining geomaterials under a variety of environmental conditions, such as variations in temperature and humidity. To this end, results from a near-to-real scale experiment (the FEBEX in-situ test1) were studied by means of a thermo-hydro-mechanical (THM) finite element approach including a consistent thermo-plastic constitutive model for unsaturated soils.