In deep geological repository involving a multi-barrier system, the engineered materials, generally made of bentonite, constitute an important mechanical, thermal and hydraulic barrier to prevent the interaction between wastes and biosphere. To better understand the THM (thermo-hydro-mechanical) processes in the clayey confining system, experimental tests must be simulated by the means of advance numerical tools. A unified thermo-mechanical constitutive model for unsaturated soils, ACMEG-TS, has been developed and implemented in the finite element code LAGAMINE. Material is considered as tri-phase non-isothermal thermo-plastic medium. The results of numerical simulations of non-isothermal infiltration tests through FEBEX bentonite are compared with the available sensors measurements and interpreted in the light of elasto-thermo-plasticity of unsaturated soils. Through those simulations, the advancements in the understanding of the involved processes brought by the ACMEG-TS model are discussed.