Numerical study of the heating-cooling effects on the geotechnical behaviour of energy piles

Energy geostructures represent a renewable and clean source of energy which can be used for heating and cooling of buildings and de-icing of infrastructures. This technology couples the structural role of geostructures with the energy supply, using the principle of shallow geothermal energy. Heat is extracted from the ground during winter and injected into the ground during summer. This represents an additional thermal loading, seasonally cyclic, which is imposed to the soil and the structure itself. In this paper, the in-fluence of temperature on the different aspects involved, accordingly to the Eurocode 7, in the geotechnical design of deep foundations is analysed. This includes mainly the admissible displacements, the structural failure (concrete) and the geotechnical capacity. The numerical results show that the thermal load has an effect both in terms of piles displacements and bearing capacity which are acceptable in normal working conditions but deserve to be considered in the design practice.