Numerical modeling of geothermal energy piles with sensitivity and parameter variation analysis of a case study

Abstract Geothermal energy piles (GEPs) combine structural load-bearing and heat-exchange functions, offering a sustainable solution for energy-efficient building foundations. This study presents a fully coupled thermo-hydro-mechanical finite element model in Plaxis 2D, calibrated against field data from the Swiss Tech Convention Center. The model successfully reproduced pile head displacements (upward heave during heating, Residual settlement after cooling) and vertical strain distributions observed in experiments, confirming its validity. A four-stage heating-cooling cycle (with a temperature difference of 21 K) revealed that volumetric expansion and contraction are most pronounced in the upper alluvium and redistributed into stiffer moraine layers. Sensitivity analysis identified the concrete modulus as the dominant factor, with notable influence of soil elastic moduli and Poisson’s ratio in specific layers. Parameter variation analysis showed that ±20% changes in these inputs had a negligible effect on the response, emphasizing the governing role of pile stiffness and thermal loading amplitude. These findings provide a robust framework for assessing GEP performance and highlight the importance of elastic properties and construction quality over minor soil variability in typical design scenarios.