Outcomes From International Workshop on Thermoactive Geotechnical Systems for Near-Surface Geothermal Energy: From Research to Practice-Article

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The paper summarizes a 2013 international workshop on thermoactive geotechnical systems—civil infrastructure that doubles as a ground-source heat exchanger. Examples include energy piles, diaphragm walls, tunnels, roadways and bridges. By using the relatively stable temperature of the shallow ground, these systems can improve heat-pump efficiency while reducing the need for separate boreholes and making use of infrastructure already required for construction.<br /><br />The workshop reviewed methods for characterizing soil, rock, concrete, heat-exchange tubing and fluids, and for assessing system performance. Thermal response tests help estimate ground and system properties, while analytical, numerical and simplified design tools model heat transfer. Thermomechanical methods assess temperature-induced stresses, strains and movements, accounting for soil–structure interaction and restraint from the building. Existing field studies generally show manageable foundation stresses and displacements, though results vary with site conditions and system design.<br /><br />Successful implementation depends on careful site investigation, appropriate heat-exchanger selection and coordination among geotechnical, structural and geothermal designers. Construction details—including tubing layout, protection against damage and concrete placement—are also important.<br /><br />Emerging applications include bridge-deck deicing, geothermal use of landfill heat, seasonal underground thermal storage and possible use of heat-exchanger tubing for pile-integrity testing. The paper also highlights barriers such as upfront costs, regulatory and insurance questions, environmental monitoring and the integration of foundation systems with building-design software.<br /><br />The authors conclude that the field has a solid basis in characterization, testing and design, but further research is needed. Priorities include performance in layered soils and soft clays, long-term effects of temperature cycling, lateral foundation behavior, improved design methods and more durable, efficient tubing. Monitoring and better coordination across disciplines will help establish reliable practice.

Keywords

thermoactive geotechnical systems

energy piles

ground-source heat exchanger

thermal response tests

soil-structure interaction

thermomechanical behavior

heat-pump efficiency

seasonal thermal storage

diaphragm walls

bridge-deck deicing