A small-scale pile has been developed in the laboratory to investigate the thermo-19 mechanical behavior of energy piles subjected to a significant number of thermal cycles. The 20 model pile (20 mm external diameter), installed in dry sand, was initially loaded at its head to 0, 21 20, 40 and 60% of its ultimate bearing capacity (500 N). At the end of each loading step, 30 22 heating/cooling cycles were applied to the pile. The long-term behavior of the pile was observed 23 in terms of pile

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... d settlement, axial force profile, soil and pile temperature, and stress in soil. 24 The results evidence the irreversible settlement of the pile head induced by thermal cycles under 25 constant load head. In addition, the incremental irreversible settlement, that accumulates after 26 each thermal cycle, decreases when the number of cycles increases. The evolution of irreversible 27 pile head settlement versus number of cycles can be reasonably predicted by an asymptotic 28 equation. 29 30