The contribution presents a numerical simulation of bentonite in an engineered barrier for nuclear waste repositories. The simulation has to be based on long time experiments, measured in years, to obtain relevant results. The understanding of bentonite behaviour which is affected by heat and moisture transport can be supported by suitable numerical models able to reproduce the main feature of the tests, where coupled thermo-hygro-mechanical formulations are inevitably required. The numerical simulation is the auxiliary analysis accompanying the in-situ test. Verification of the suitable instruments' setup, the number of sensors, their type, and the location is essential for the construction of further tests. Moreover, the simulation helps to predict long-term experiment behavior for bentonite sampling. [ABSTRACT FROM AUTHOR]