The aim of this paper is numerical analysis of the consolidation processes in soils due to high temperature. A fully coupled finite element model for non-isothermal elasto-plastic multiphase materials at high temperature is therefore developed in the framework of Porous media mechanics for fully coupled multi-phase porous media. The non-isothermal elasto-plastic consolidation processes of a Boom clay column due to a temperature rise of the top surface from 30 to 150 degrees C is studied in detail, in order to analyze the coupled thermo-hydro-mechanical behaviour of the material when the temperature is above the boiling value and water phase change develops inducing variably saturated conditions. The numerical results reveal a temperature increase over time in the column; desaturation starts from the top surface, triggered by a water vapor mass exchange with the ambient at a RH=95%. When the temperature reaches the boiling value, phase change for the liquid water occurs and desaturation proceed much faster, developing high capillary pressures and inducing plastic strains, swelling and a final settlement when reaching the steady state conditions.