Analytical Solutions for Thermomechanical Coupling of Semifloating Energy Piles in Multilayer Soils

Energy piles face challenges in ensuring functionality, safety, and efficient operation due to their complex working state under thermomechanical coupling conditions, which poses a problem that requires an effective assessment method. To address this, in this study, the equilibrium, kinematics, thermoelasticity, and elastic constitutive relationships of energy piles are formulated, and a simple and direct analytical solution is derived for the axial displacements, strains, and stresses of semifloating energy piles in multilayer soils under thermomechanical coupling loads. After validating the analytical solutions with existing literature, critical factors influencing the thermomechanical coupling behavior, including thermal and mechanical loads, pile end constraints, length-to-diameter ratios (L/D ratios), layer stiffness, and layer thickness, are also analyzed. Key results show that mechanical loads and L/D ratios have a more significant impact on the pile head than on the pile tip, whereas thermal loads cause more significant stress changes at the pile tip. The novelty of this study lies in the proposed analytical solution, which provides a simple and reliable quantitative assessment method that allows engineers to perform rapid and accurate design.