Design Tools for Thermoactive Geotechnical Systems-Article

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The paper reviews analytical and numerical tools for designing thermoactive geotechnical systems, focusing mainly on energy piles. It distinguishes thermal analysis, which predicts heat exchange and ground temperatures, from thermomechanical analysis, which assesses pile stresses, strains and movements under heating and cooling.<br /><br />Thermal design methods adapted from borehole heat exchangers are computationally efficient and often useful, but may not accurately capture the larger thermal mass and transient response of piles. Some tools also rely on simplified geometries and boundary conditions. Thermomechanical methods include empirical rules, load-transfer models and finite-element or other numerical analyses. Load-transfer models have been compared with field tests, but no approach has yet been systematically validated across different soils, pile types and loading conditions.<br /><br />Key limitations include inadequate representation of repeated heating and cooling, pore-water pressure changes, radial stress effects and interactions among thermal, hydraulic, structural and geomechanical processes. Long-term performance and systems with irregular geometries or structures other than piles also need better analysis. Existing design guidance is limited, and there are no comprehensive national codes for integrating heat exchangers into geotechnical structures.<br /><br />The authors recommend validating current tools against field and laboratory data, establishing consistent testing and reporting protocols, and building performance databases. Further research should improve constitutive models and develop both practitioner-friendly simplified tools and advanced numerical models. Design guidance should address thermal and geotechnical performance together, clarify appropriate safety margins and limit-state procedures, and support practitioners through practical recommendations and training. Overall, the paper calls for an extensive design guide for energy geostructures grounded in field observations, experiments and numerical studies.

Keywords

energy piles

thermoactive geotechnical systems

thermal analysis

thermomechanical analysis

heat exchange

ground temperature

load-transfer models

finite-element analysis

geotechnical design guidance

thermal-hydraulic-mechanical interactions