THERMO-MECHANICAL BEHAVIOR AND STRUCTURAL DESIGN OF GEOTHERMALLY ACTIVE PILES

Contemporary living and the need for renewable energy sources demand innovative “green” technologies that offer structural improvement and simultaneously provide more economical and long-term cost-friendly solutions. In geotechnical engineering, shallow thermo-active geo-structures look like one of the most promising concepts. Thermo-active geo-structures may include base slabs, piles, retaining walls, and supporting elements for tunnels, such as linings and anchors, which besides the mechanical (bearing) function have a thermal function working as heat exchanger systems. In most cases, these structures are piles, whose behavior could be predicted using different approaches. Utilizing foundation systems as heat exchangers has received significant public interest worldwide, as these energy geo-structures can constitute a clean, renewable, and economical solution for space heating and cooling. Thermo-active geo-structures are considered innovative alternatives to traditional Ground Source Heat Pump (GSHP) systems for space heating and cooling, having the potential to reduce the upfront cost of the GSHP systems. Hence, the structural element gets an additional thermal function as piles, retaining walls, tunnel linings pavements, etc. This way they will be loaded by the thermal change or deference in temperature which must be considered during the design phase. The most common type of energy geo-structures are energy piles, most likely due to their significant geometrical similarities with the thoroughly studied traditional vertical borehole systems, attempting to adapt the available thermal design methods for the traditional borehole systems for energy pile design, commercial aspects, benefits of using Energy Geotechnical Structures (EGS) compared to standard Borehole heat exchanger systems. Keywords: Geotechnical engineering, thermo-active structures, geothermal energy, geothermal piles