Deep geological repository involving a multi-barrier system constitutes one of the most promising options to isolate high-level radioactive waste from the human environment. In order to certify the efficiency of waste isolation, it is essential to understand the behaviour of the confining geomaterials under a variety of environmental conditions. The efficiency of Engineered Barrier Systems (EBS) is highly based on the complex behaviour of bentonite. To improve the understanding of the processes involved in the EBS, results from a near-to-real scale experiment, the FEBEX experiment, are studied by means of a thermohydro- mechanical (THM) finite element approach including a consistent thermo-plastic constitutive model for unsaturated soils. The model also features a coupled THM approach of the water retention curve. The extended literature available on the behaviour of the FEBEX bentonite is used to calibrate the parameters. The results of the numerical simulations are compared with sensor measurements and show the ability of the model to reproduce the main features of the mechanical behaviour of the system. The hydraulic and thermal response is also realistically described by the model. The link between the confined swelling behaviour as tested in laboratory and the results of the real-scale experiment is clearly established by this simulation.