Abstract: Applying energy pile technology to support piles not only addresses structural safety issues, but also facilitates resource recovery and reuse. Based on the foundation pit support project of high-voltage line merging and reconstruction of a utility tunnel in Xinhe Business District of Jiaozuo City, thermal response tests of energy support piles were conducted before and after foundation pit excavation. Additionally, thermal response field tests of energy support piles under different interval ratios were performed once the excavation stabilized. The inlet/outlet water temperature, pile temperature, and strain change data were measured. Preliminary discussions covered heat transfer performance, thermal stress, and pile bending moments of energy support piles. Results indicate that under these test conditions, pit excavation enhances the heat transfer capacity of the energy support piles, while reducing additional temperature stress on the pile body. For energy support piles with different interval ratios, the heat transfer capacity improves as the interval ratio decreases. Additional temperature stress on the pile body increases with more cycles and decreases with depth. The bending moment of pile body caused by pit excavation is 128.98 kN·m at −8.0 m, decreasing towards both ends. As pile temperature increases, the bending moment initially decreases and then rises. For energy support piles with different interval ratios, the bending moment of pile body increases with the increase of interval ratio, reaching a maximum of 7.12 kN·m at −4.0 m when the interval ratio is 2.0.

Key words: energy support pile, pit excavation, interval ratio, heat transfer performance, thermal response