The Influence of Cyclic Thermal Loading on the Response of Energy Piles Subjected to Combined Axial/Horizontal Loading

In the present study, the potential use of energy piles to support the foundation of bridge abutments, high-rise buildings, earth retaining structures, seafront structures, or buildings located on sloping ground has been investigated. In such structures, energy piles are subjected not only to combined axial/horizontal mechanical loads but also to thermal loads. A small-scale laboratory test was conducted using an instrumented model energy pile embedded in dry sand, in which model pile was loaded at its head to the combined allowable axial/horizontal mechanical loading prior to ten heating/cooling cycles with temperature variation of ±1°C. The results evidenced that imposing heating-cooling cycles to the model pile resulted in irreversible settlement and horizontal displacement of the pile head, which gradually accumulated over time and reached 0.6%D and 1.1%D after ten heating/cooling cycles, respectively. The influence of heating/cooling cycles on the mechanical response of the model energy pile was more predominant in the horizontal direction compared to the axial direction. The highest increment of irreversible pile head settlement and horizontal displacement was induced by the first heating-cooling cycle; however, subsequent increments decreased and exhibited a tendency towards stability as the number of thermal cycles increased.