Abstract：Based on the theory of heat conduction，this paper presents governing differential equations of ground temperature field，boundary conditions，initial conditions and finite element model for single pile in permafrost with the consideration of air temperature，hydrogeological conditions，concrete temperature，initial ground temperature field，and phase-change effect. For a cast-in-place bored pile in a practical bridge structure that was built in the representative humid permafrost in the Qinghai—Tibet plateau，the ground temperature field of refreezing process was calculated. The temperatures along the pile body varied with the depth and refreezing time，which were used to evaluate the variation of bearing capacity of the single pile and influence of temperatures on the plan of bridge construction according to the bridge code. The presented procedure and conclusions achieved can provide a theoretical basis for shortening construction period and laying out bridge construction plan in permafrost regions.
