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A preliminary study of the thermo-mechanical behavior of the energy pile in expansive clays

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  • Bi, Gang
  • Yang, Long
  • Gou, Xinyu
  • Xu, Hongzhong
  • Sun, Yijie
  • Cheng, Zhe
  • Zhao, Jialin

Abstract

This study investigates the thermo-mechanical behavior of energy piles in expansive clay through laboratory modeling tests, integrating heat exchange analysis and soil-pile interaction mechanics. Using Fiber Bragg Grating (FBG) sensors, three cases were compared: (A) expansive clay, (B) sand, and (C) soaked expansive clay. Results show that during heating/cooling phases, heat exchange efficiency in expansive clay is 33 % (10 W/m) and 83 % (30 W/m) of that in sand, respectively, owing to moisture-sensitive swelling-shrinking behavior. Thermal cycles induce 2–3 times larger displacement amplitudes in expansive clay than in sand, with irreversible plastic deformation evident in hysteresis curves. Axial stress in expansive clay shifts from +350 kPa (tension) during heating to −400 kPa (compression) under saturated conditions or when replaced by sand. The combined effect of moisture and temperature exacerbates deformation by 40–60 % in Case C, underscoring the need for thermo-hydro-mechanical coupling models in expansive soil design.

Suggested Citation

  • Bi, Gang & Yang, Long & Gou, Xinyu & Xu, Hongzhong & Sun, Yijie & Cheng, Zhe & Zhao, Jialin, 2026. "A preliminary study of the thermo-mechanical behavior of the energy pile in expansive clays," Renewable Energy, Elsevier, vol. 256(PE).
    • Handle: RePEc:eee:renene:v:256:y:2026:i:pe:s0960148125019767
    DOI: 10.1016/j.renene.2025.124312
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    References listed on IDEAS

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