Deformation characteristics of energy pile group under horizontal loading

Current research on the thermodynamic characteristics of the energy pile group foundation under external load mainly focuses on the vertical load, however the study on impact of horizontal load is limited. To investigate the deformation characteristics of horizontally loaded energy pile groups under asymmetric heating or cooling conditions, a single pile within the 2×2 energy pile group was heated and cooled through the model tests, and a three-dimensional finite element model of the energy pile group was established. The measured data and numerical results were compared and validated, and parametric analysis was conducted to study the thermo-mechanical response of the pile during the operation of a single pile for the energy pile group. Results indicate that the findings of numerical model and model tests are generally consistent. The bending moment was mainly concentrated in the upper part of the pile, its peak bending moment and inflection point are located 0.23L₁ and 0.8L₁ below the soil surface, and the horizontal displacement of the pile also decreased with the increasing depth (L₁ is the effective buried depth of pile). The horizontal loading had a greater impact on the deformation characteristics of the pile, but the influence of temperature could not be ignored. As the temperature increased or decreased, the bending moment and displacement of the energy pile tended to increase. Compared with the only subjected to horizontal load, the increase in water temperature by 10 ℃ and 20 ℃ led to an increase in the M_max (peak bending moment) of the energy pile by about 23.36% and 25.46%, and an increase in the horizontal displacement of the pile top by about 20.59% and 21.93% when the horizontal load and temperature variation were applied simultaneously. The decrease in water temperature by 10 ℃ and 20 ℃ resulted in an increase of approximately 23.48% and 24.39% in the energy pile M_max (peak bending moment), and an increase of approximately 17.97% and 21.27% in the horizontal displacement of the pile top.