Investigation of Cyclic Thermo-mechanical Interactions in Pile Groups under Varying Thermal Loading

In this study, numerical investigations were performed to examine the thermo-mechanical characteristics of the geothermal pile group having geothermal and conventional piles arranged under a single pile cap. The geothermal piles were subjected to varying degrees of thermal loading, over five thermal cycles of heating and cooling. The piles and pile cap were simulated to behave in a linear-elastic manner, and the soil was simulated using the Mohr-Coulomb plasticity model. The analyses were performed for the pile groups having different pile spacing. The investigation findings indicate that the interactions between piles, pile cap, and the surrounding soil become intricate due to cyclic thermal loading and unloading of the geothermal piles. The thermal consequences induced by cyclic temperature variations are more pronounced in the corner geothermal pile and the side conventional pile sustains more significant thermally induced effects than the central conventional pile. Differential cyclic pile displacements in the pile cap leads to varying load distribution among all the piles. The pile location plays a significant role in determining the uneven distribution of loads within the piles and the soil. Further, the magnitude of thermal load and thermal cycles govern the load-displacement mechanism of the pile cap, piles, and supporting soil.