Sensitivity Analysis of Elastic Thermo-Mechanical Energy Pile Response Based on Dimensionless Form of Analytical Solutions

Energy piles are multifunctional deep foundations that structurally support buildings while enabling heat exchange between the superstructure and shallow subsurface. It is crucial for the wider use of energy piles and thus reliance on clean, renewable shallow geothermal energy for supplemental space heating and cooling to understand thermal and combined thermo-mechanical load transfer. To this end, previously developed and successfully validated analytical solutions are transformed into a unified dimensionless form, and the minimum set of controlling composite parameters is identified through rigorous application of the Buckingham Π theorem. A multifaceted solution space is explored through a sensitivity analysis performed across a wide range of controlling parameters and under different boundary conditions. The results show that the mechanisms of load transfer for thermal and mechanical loads are inherently different. In a very stiff soil, mechanical load is supported by the soil, while thermal load generates significant stress in the pile. Thus, the thermo-mechanical stress response is dominated by the thermal response. In a very soft soil, mechanical load is supported by the pile while stresses generated by thermal load are negligible. Thus, the thermo-mechanical stress response is dominated by the mechanical response.