THERMAL SCIENCE
International Scientific Journal
Thermal Science - Online First
online first only
Performance of static drilled root energy piles under seasonal thermal loading: A study of monotonic heating in summer
ABSTRACT
Energy piles are subjected to the combined effects of thermal and mechanical loads, requiring high load-bearing capacity and efficient heat transfer. This study introduces the concept of energy piles into static drill rooted piles (SDRP), forming a new structure known as static drilled rooted energy piles (SDREP). Model tests were conducted under monotonic heating cycles to evaluate their performance, primarily for summer cooling applications. The results show that the temperature distribution patterns of SDREP and ordinary energy piles (OEP) are generally similar. However, SDREP exhibits lower pile temperature fluctuations and a higher temperature field in the surrounding soil. Under heating cycles, the additional thermal stresses in SDREP gradually increase with the number of cycles, and the peak stress occurs closer to the pile tip. During 20 heating cycles, the soil pressure at the pile tip of SDREP was always lower than that of OEP. The pile head displacement also showed different behavior: the pile head displacement of SDREP increased upward, with a final displacement accumulation of 0.19% D. The pile head displacement of OEP showed a significant downward displacement, with a final displacement accumulation of 0.57% D. After 20 heating cycles, the ultimate bearing capacity of SDREP increased by 10%. These findings provide insight into the thermo-mechanical behavior of SDREP and provide theoretical support for its application in energy pile engineering.
KEYWORDS
PAPER SUBMITTED: 2025-05-16
PAPER REVISED: 2025-07-23
PAPER ACCEPTED: 2025-07-24
PUBLISHED ONLINE: 2025-09-13
- Ai, Z.Y.,W.Y. Feng, The mechanical response of energy pile groups in layered cross-anisotropic soils under vertical loadings, Energy, 292. (2024), p. 130531
- Luu, G.T., et al., Enhancing long-term viability of energy pile with heat sink systems in tropical monsoon climates: Implementation strategies and performance analysis, Energy and Buildings, 328. (2025), p. 115119
- Cao, X., et al., Feasibility assessment of implementing energy pile-based snowmelt system on a practical bridge deck in diverse climate conditions across China, Energy, 290. (2024), p. 130317
- Chang, H., et al., Experimental study of phase change energy pile based on Gum Arabic and Polyethylene Glycol 600 under multiple Thermal-Cold cycles, Construction and Building Materials, 438. (2024), p. 137109
- Fadejev, J., et al., A review on energy piles design, sizing and modelling, Energy, 122. (2017), pp. 390- 407
- Kong, G., et al., Seasonal performance of an energy pile heat pump system and prediction of building thermal load, Applied Thermal Engineering, 241. (2024), p. 122359
- Song, H., et al., Thermomechanical analysis of dissimilar energy pile groups using a load transfer method, Renewable Energy, 254. (2025), p. 123708
- Han, C.,X. Yu, An innovative energy pile technology to expand the viability of geothermal bridge deck snow melting for different United States regions: Computational assisted feasibility analyses, Renewable Energy, 123. (2018), pp. 417-427
- Wang, Z., et al., Influence of silicon carbide incorporation on the macroscale and microscale heat transfer characteristics of energy piles, Renewable Energy, 237. (2024), p. 121717
- Zhang, R., et al., Experimental study on energy pile thermal-structure response during high temperature heat storage, Journal of Energy Storage, 120. (2025), p. 116458
- He, F., et al., Effects of thermal loading conditions on the thermo-mechanical response of energy pile at different depths, Geothermics, 131. (2025), p. 103392
- Chang, H., et al., Thermo-mechanical response of energy piles under monotonic cooling cycles and various mechanical loading levels, Journal of Energy Storage, 113. (2025), p. 115672
- Zhang, G., et al., Full-scale tests of a long energy pile subjected to separated and coupled thermo16 mechanical loads, Proceedings of the Institution of Civil Engineers - Geotechnical Engineering, 177. (2024), 5, pp. 564-577
- Dupray, F., et al., Heat-exchanger piles for the de-icing of bridges, Acta Geotechnica, 9. (2014), pp. 413-423
- Zhao, H., et al., An approach for analysis of a single energy pile subjected to a horizontal load in sand, Case Studies in Thermal Engineering, 56. (2024), p. 104289
- Song, H., et al., Long-term thermomechanical behavior of energy piles under inclined load, Journal of Energy Storage, 99. (2024), p. 113258
- Zhang, D., et al., Influence of a rigid cap on thermo-mechanical behavior of nonsymmetrical thermally loaded energy pile group in clay, Canadian Geotechnical Journal, 60. (2022), 5, pp. 654-668
- Ghezellou, A., et al., Thermomechanical response of energy piles in dry sand under monotonic cooling with varying end-support conditions, Journal of Energy Storage, 82. (2024), p. 110469
- Chang, H., et al., Experimental study on the thermo-mechanical behavior of steel pipe energy pile groups with and without phase change material, Geothermics, 129. (2025), p. 103304
- Kong, G., et al., Behaviours of a belled energy pile under heating-cooling cycles, Journal of Building Engineering, 72. (2023), p. 106652
- Jiang, G., et al., Thermo-mechanical behavior of driven energy piles from full-scale load tests, Energy and Buildings, 233. (2021), p. 110668
- Kong, L.-p., et al., A study on heat transfer characteristics and pile group influence of enhanced heat transfer energy piles, Journal of Building Engineering, 24. (2019), p. 100768
- Lee, S., et al., Dual performance of novel steel pipe heat exchangers equipped in cast-in-place energy pile, Energy and Buildings, 234. (2021), p. 110725
- Chang, H., et al., Thermo-mechanical behavior of PCM-enhanced steel pipe energy piles, Applied Thermal Engineering, 276. (2025), p. 126917
- Yang, W., et al., Numerical evaluations on the effects of thermal properties on the thermo-mechanical behaviour of a phase change concrete energy pile, Energy and Built Environment, 4. (2023), 1, pp. 1-12
- Shahidi, S., et al., Experimental investigation on the efficiency of the phase change materials for enhancing the thermal performance of energy piles in sandy soils, ENERGY AND BUILDINGS, 298. (2023)
- Xia, C., et al., Investigation of heat transfer characteristics in steel fiber-reinforced energy piles utilizing steel tubes for PCM encapsulation, Energy, 326. (2025), p. 136273
- Lee, S., et al., Data-driven prediction of long-term thermal performance for steel pipe heat exchanger (SPHX) energy piles, Geothermics, 129. (2025), p. 103292
- Chang, H., et al., Thermo-mechanical response of static drilled rooted energy piles under monotonic cooling cycle, Construction and Building Materials, 456. (2024), p. 139276
- Zhang, Q., et al., Thermal performance and applied evaluation of the pre-bored grouting planted nodular pile in warm frozen soil, Applied Thermal Engineering, 248. (2024), p. 123178
- Zhou, J.-j., et al., Bearing capacity and load transfer mechanism of a static drill rooted nodular pile in soft soil areas, Journal of Zhejiang University SCIENCE A, 14. (2013), 10, pp. 705-719
- Yu, J.-l., et al., The frictional capacity of smooth concrete pipe pile-cemented soil interface for pre-bored grouted planted pile, Acta Geotechnica, 18. (2023), 8, pp. 4207-4218
- Zhou, J.-j., et al., A field study on the behavior of static drill rooted nodular piles with caps under compression, Journal of Zhejiang University-SCIENCE A, 16. (2015), 12, pp. 951-963
- Zhou, J., et al., Model tests comparing the behavior of pre-bored grouted planted piles and a wished-in-place concrete pile in dense sand, Soils and Foundations, 59. (2019), 1, pp. 84-96
- Ding, X., et al., Thermo‒mechanical behavior of energy pile group in dry sand subjected to a horizontal load, Renewable Energy, 233. (2024), p. 121170
- Chang, H., et al., Thermo-mechanical behavior of steel pipe energy piles under thermal imbalance cycles, Construction and Building Materials, 447. (2024), p. 138026
- Kong, G., et al., Behaviours of a belled energy pile under heating-cooling cycles, Journal of Building Engineering, 72. (2023)
- Bourne-Webb, P.J., et al., A framework for understanding energy pile behaviour, PROCEEDINGS OF THE INSTITUTION OF CIVIL ENGINEERS-GEOTECHNICAL ENGINEERING, 166. (2013), 2, pp. 170-177
- Amatya, B.L., et al., Thermo-mechanical behaviour of energy piles, Géotechnique, 62. (2012), 6, pp. 503-519
- Zhang, D., et al., Influence of a rigid cap on thermo-mechanical behavior of nonsymmetrical thermally loaded energy pile group in clay, Canadian Geotechnical Journal, 60. (2023), 5, pp. 654-668
- Abu-Farsakh, M.Y.,A. Idries, Enhancement of clay-concrete interface strength through applying cycles of heating and cooling, Geothermics, 113. (2023), p. 102772
- Yazdani, S., et al., Influence of temperature on soil-pile interface shear strength, Geomechanics for Energy and the Environment, 18. (2019), pp. 69-78