Effects Of Self-Weight on Thermomechanical Response of Energy Piles-Paper

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The study develops analytical solutions for the axial displacement, strain, and stress of energy piles while accounting for pile self-weight alongside thermal and mechanical loads. The solutions extend earlier weightless-pile models and are evaluated against centrifuge test results and predictions for a full-scale semi-floating pile.<br /><br />For an end-bearing pile, comparison with centrifuge tests showed that self-weight’s influence declines as heating increases. At 5°C, including self-weight reduced maximum displacement by about 45% and changed maximum vertical stress by about 43%; at 19°C, these effects fell to roughly 11% and 16%, respectively.<br /><br />For a semi-floating pile under a compressive load and heating or cooling, the importance of self-weight depended chiefly on soil–pile interface stiffness. In a stiff soil profile, weighted and weightless predictions were nearly identical. In a more compliant profile, self-weight noticeably affected displacement, strain, and stress, and shifted the location of the pile’s zero-displacement point. Its influence also became less pronounced as thermal loading increased.<br /><br />Overall, the findings indicate that neglecting self-weight may be reasonable for energy piles in stiff soils or under substantial thermal loading, but it can affect predictions in softer interface conditions. The analytical solutions offer a practical means of assessing these effects without complex numerical modeling.

Keywords

energy piles

axial displacement

thermal loading

self-weight

vertical stress

strain analysis

analytical solution

centrifuge tests

semi-floating pile

soil-pile interface stiffness