Etude expérimentale du comportement thermomécanique des pieux énergétiques dans l'argile

The paper presents a study on the thermo-mechanical behavior of energy piles in clay using small-scale and full-scale tests. For the small-scale energy pile, developed in laboratory, thermo-mechanical tests were performed by applying a heating/cooling cycle to the pile under constant axial load. The results show pile head heave during heating and settlement during cooling. Irreversible settlement was observed after the thermal cycle. Tests performed with various axial loads show that the thermal irreversible settlement is greater under a higher axial load. For the full-scale energy pile, 0.4 m in diameter and 12 m long, a heating phase was applied during one month that allows increasing the pile's temperature from the initial value (13°C) to 33°C. The results show that soil temperature measured at 4 m (from the pile axe) was not influenced by this heating phase. The heat flux injected to the soil during this phase was about 700 W. This preliminary test was useful for the design of the future experiments where coupled thermo-mechanical loading program was planned for this project.