| Title | Numerical analysis of thermo-active piles under thermal cyclic solicitation |
|---|---|
| Authors | Suryatriyastuti, Mroueh, Burlon |
| Year | 2013 |
| Conference | European Geothermal Conference |
| Keywords | thermo-active pile, thermal deformation, soil–pile interface, cyclic loading. |
| Abstract | Thermo-active piles are one of current trending technology in thermal building system, the bi-function foundations acting as structural and heat exchanger elements. Fluid circulating in the piles is set to vary from –10°C to 35°C of the ground temperature, producing heating and conditioning of the building. This heat transfer induces change in ground temperature equilibrium and consequently generates additional stress in the pile foundations. Moreover, under the seasonal temperature variation, thermoactive piles undergo an alteration of contraction– dilatation throughout the year. From the geotechnical point of view, this cyclic thermal loading leads to modify the long-term mechanical resistance of the pile foundations, concerning the displacement towards the building and mobilised friction at the soil–pile contact zone. This paper studies at the first time the heat diffusion in thermo-active pile system in order to determine the temperature in the pile, in the ground, and at the soil–pile contact zone. The impact of temperature variation on the mechanical resistance at the zone of contact is discussed. Analysis of thermally induced mechanical behaviour is conducted in transforming the thermal gradient in the pile into an equivalent mechanical load. Consideration of cyclic loading effect is taken into account by applying a constitutive law at the soil–pile interface, the Modjoin law. This law has both of isotropic and kinematic hardening thus can calculate cyclic degradation in the thermo-active pile during the thermal operation. |