Thermo-mechanical characteristics of laterally loaded energy piles under multiple heating-cooling cycles in mountain area

In this paper, model tests of energy piles used in mountain area under asymmetry filed condition with and without an external lateral load under multiple heating-cooling cycles were conducted. The asymmetry of the soil will produce asymmetric temperature field and stress field in mountain area. The variation of pile top displacement, horizontal soil pressure, and pile bending moment due to cyclic temperature load were measured and analyzed. The results showed that the pile top horizontal displacement with an external lateral load decreased when the energy pile was heated and increased when it was cooled. However, the variation trends of pile top horizontal displacement with and without an external lateral load showed a significant difference. When the pile subjected to an external load was heated, the soil pressure at the upper part behind the pile would increase and that at the lower part would decrease, and the change was opposite during cooling. The bending moment would be changed by the thermal load, and it increased during heating with an external lateral load, while the variation of bending moment was not obvious during cooling.