Abstract: Energy pile is a relatively new foundation technology for extracting the shallow geothermal energy from surrounding rock and soil mass when transferring the load of the upper building, which poses a new challenge for the design and safety service of pile foundations. In the view of the practical application of energy piles, this paper focuses on two key scientific issues of heat transfer performance and bearing performance of energy piles. The main research problems related to energy piles are introduced from the following four types of research: heat transfer of energy piles, structural response characteristics of energy piles, bearing performance of energy piles, and load transfer mechanism of energy piles. On this basis, the applicability of current heat transfer model of energy piles, the bearing characteristics of single pile and pile groups under heat exchange, bearing performance and structural safety under long-term operating conditions are discussed. Finally, future research on energy pile engineering is prospected. The analysis results are significant for ensuring structural safety and developing the shallow ground energy rationally.

Key words: shallow geothermal energy, energy piles, heat transfer, bearing performance, research status