Performance of complex energy geostructures

Energy geostructures are innovative technologies that combine the functions of structural support and geothermal energy harvesting. To date, theoretical, computational, and experimental investigations have explored the performance of distinct types of energy geostructures, i.e. energy piles, walls, slabs, and tunnels. However, there seemingly exists limited knowledge on the performance of complex energy geostructures that integrate different types of geostructures in a unique building solution, despite being common in practice. This work addresses this knowledge gap by providing a computational study of the performance of two real-world installations of complex energy geostructures. The study resorts to 3-D, time-dependent, thermo-mechanical finite element simulations that consider the dynamic building thermal energy needs and the operation of the considered complex energy geostructures over a design lifetime of fifty years. The work reveals that the energy, geotechnical, and structural performance of complex energy geostructures is far from trivial. Especially the structural performance of complex energy geostructures exhibits responses that are counterintuitive and different compared to those that would be predicted by simplified modeling approaches referring to individual types of energy geostructures. Accordingly, this investigation calls for attention in the analysis of complex energy geostructures and judgment in the application of simplified design methods.