Abstract: Combining bridge row piles with energy piles to create energy row piles can harness shallow geothermal energy for bridge deck deicing in winter and cooling in summer, respectively, while also supporting the mechanical loads of the bridge deck. This study investigates the thermo-mechanical response of energy row piles under heating-cooling cycles through field tests, and analyzes the interactions among energy row piles, slab, and unheated piles. An interface model considering the cyclic shear characteristics of the pile-soil interface is developed in a finite element software, and thermo-mechanical coupling numerical models of energy row piles are established to further explore the changes and mechanisms of long-term settlement of energy row pile under the combined effect of mechanical loads and heating-cooling cycles. The findings reveal that interactions among the energy row pile, slab, and unheated piles can result in load redistribution, leading to high thermally induced stresses of approximately 80% of the maximum thermally induced stress of the energy row pile (i.e. 1.1 MPa) at the top of the energy row piles due to strong restraining effects. Meanwhile, the slab experiences tensile stress exceeding the tensile strength of C30 concrete, reaching 3.75 MPa. Moreover, when the mechanical load is large, energy row piles progressively develop long-term settlement with an increasing number of thermal cycles, exhibiting a negative exponential growth pattern. This phenomenon is attributed to the mechanical load driving the pile-soil interface toward its limiting state, where cyclic shear at the interface readily induces plastic shear displacements, ultimately resulting in the long-term settlement of the energy row piles.

Key words: bridge energy row piles, thermo-mechanical characteristic, heating-cooling cycle, field test, numerical simulation.