Thermo-plasticity of soil has gained increasing attention due to its importance for the analysis and design of many emerging infrastructures such as geothermal structures. However, its implementation in numerical investigation is still very limited. Energy pile is a green technology widely used for cooling and heating to reduce the consumption of energy. Previous studies mainly assume the surrounding soil is a simple thermo-elastic material, which can lead to a non-conservative design of floating energy piles subjected to thermal cycles. This talk will focus on the cyclic thermo-mechanical behaviour of floating energy pile groups in soft clay. An advanced bounding surface constitutive model capable of simulating thermal cyclic behaviour will be introduced. This model using a memory surface is developed and implemented into a finite element code to investigate the underlying mechanism of floating energy pile groups in clay. Computed results are calibrated against centrifuge model tests carried out in the Hong Kong University of Science and Technology. Parametric studies are performed to improve the design of floating energy pile groups in the short-term and long-term. Fundamental mechanisms and design implements on ratcheting pile settlements with thermal cycles (serviceability limit state) and reduction of shaft resistance (ultimate limit state) due to the decrease in the horizontal stress resulting from plastic soil contraction will be revealed, discussed and explained.