Energy pile is a new energy-saving and emission-reduction technology by installing heat exchange tubes in traditional pile foundations.In this paper

PHC energy piles were formed by embedding heat exchange tubes in the PHC piles.The single-U and double-U thermal response tests（TRT）were conducted.The distributed fiber optic sensing technology was used to monitor the temperature and strain distribution of the pile body

through which the temperature and strain changes of the energy pile were obtained during the TRTs.It was found that the energy in the initial stage of heating cannot be quickly transferred to the soil around the pile.Heat accumulated in backfilled sand in the hollow center of the energy pile.The temperature rise of the pile body was not obvious during the whole process

and the heat transfer was relatively inefficient.The TRTs reveal the thermal and mechanical changes of the PHC energy piles

which provide a basis for the optimized design of the PHC energy piles and the evaluation of performance of heat transfer.