Cyclic Pile-Soil Interaction Effects on Load-Displacement Behavior of Thermal Pile Groups in Sand

This paper highlights the cyclic pile-soil interactions and load-displacement behavior of thermal piles in friction and end-bearing pile groups. Numerical investigations of pile groups with different pile arrangement have been performed under equal magnitudes of mechanical and thermal loading. The concrete piles and pile cap are considered as thermo-elastic material and sand is simulated as elasto-plastic material. Parametric studies have been performed for different rigidity of end-bearing stratum and different pile cap thickness. Results are presented for base displacement-time response of piles, load-displacement response of piles, temperature evolution and thermally induced displacements in surrounding soil, vertical stresses along pile depth, and load distribution in piles through the pile cap. The results conclude that thermal piles experience increased pile head uplift in successive thermal heating cycles which is significant for the piles supported over rigid rock stratum. The thermal uplift of piles results in soil heave near the pile-soil interface. The set-up of higher soil temperature after cyclic heating and cooling of the piles is also noted. Cyclic thermal interactions among thermal piles and surrounding soil induce variations in load-displacement pattern of these piles which need consideration for ensuring structural safety requirements.