Thermo-mechanical finite element analyses of energy walls

Energy walls are thermo–active diaphragm walls that embed heat exchanger pipes with the pur-pose to exploit the thermal energy of the subsoil. Their geotechnical and structural performance is related to both thermal and mechanical loads and still needs to be thoroughly investigated. To this purpose, three–dimensional thermo–mechanical finite element analyses allow to highlight the effects of the heat transfer pro-cess on the soil temperature field, on the wall and on the soil–structure interaction, in terms of internal actions and earth pressures. The main findings show that the effects of the thermal loads can be considered admissible for the geostructure, in terms of its global stability and structural safety, though they are generally not negligi-ble. Unexpected overstress conditions can occur, such as tensile stresses and out–of–plane effects, whose magnitude depends on the thermal boundary conditions and on the constraint degree of the structure.