Thermoplastic Analysis of a Thermoactive Pile in a Normally Consolidated Clay

The use of shallow geothermal systems for buildings and infrastructure conditioning has numerous recognized environmental and potential economic benefits and is expected to contribute to climate change mitigation. These systems are already used in many countries and are foreseen in many more. The study of their behavior is a subject of current research interest, including thermoactive or energy geostructures. In this work the mechanical effects of a thermal action, reflecting seasonal atmospheric conditions prevalent in Lisbon, Portugal, on a single 20-m-long thermoactive floating pile with different load levels, embedded in a normally consolidated saturated clay (speshwhite kaolin), are evaluated. For this purpose a critical state elastoplastic soil model with thermal hardening was formulated, implemented, and calibrated with experimental results for thermal expansion available in the literature. The numerical analyses performed revealed that the mechanical effects on the pile caused by thermal action can be significant.