The thermomechanical behaviour of horizontally loaded energy piles in saturated clay was investigated in this study. Based on model-scale tests, a model energy pile underwent 10 heating-cooling cycles. The temperature variation, pore water pressure, soil pressure in front of the pile, pile top displacement, and pile bending moment were measured. The results showed that the thermally induced pore water pressure in the upper part of the surrounding soil gradually dissipated with increasing number of thermal cycles, whereas it gradually accumulated in the lower part of the soil. The thermally induced horizontal displacement of the pile top increased with an increasing number of thermal cycles, reaching 2.28% D (D is the pile diameter) but at a decreasing rate. In addition, the maximum bending moment, which affected the failure of the pile, occurred at a depth of 0.375L (L is the effective pile length) below the soil surface and increased with increasing number of thermal cycles.

Energy piles, as innovative energy underground structure, serve the dual purpose of shallow extracting geothermal energy while bearing the upper building load. There are few studies on the thermomechanical properties of energy piles under combined horizontal and vertical loads. The temperature change of pile body under combined horizontal and vertical loads will result in variations in pile bending moment, horizontal and vertical displacement, etc. This paper investigated the deformation characteristics of energy piles under combined vertical and horizontal loads through model tests with 10 heating-cooling cycles applied to the piles. The results showed that the heating-cooling cycles under combined load led to further increase in the pile bending moment, particularly affecting the middle of the pile, with the maximum increase in pile bending moment reaching 117%. Additionally, the heating-cooling cycles caused cumulative displacement at the top of the pile. The vertical displacement of the test pile increased by 0.201 mm, and the increase in horizontal displacement due to the thermal cycles reached 1.46% D (D is the diameter of the pile). Simultaneously, the heating -cooling cycles induced a forward tilt of the pile, with the tilt angle reached 1.88x10(-3) rad after 10 heating-cooling cycles and gradually increasing with the number of thermal cycles. Moreover, the soil pressure in front of the pile decreased during heating, while increased during cooling.