Refreezing Process of Ground for Concrete Pile Group Foundation with Hydration Heat in Cold Regions

In this paper, for concrete pile group foundation with hydration heat in permafrost, the unit area heat flow rate on the pile hole wall caused by concrete hydration heat and the governing differential equations of ground temperature field were presented to solve the problem of refreezing process of the ground. In the proceeding the air temperature, hydrology-geology conditions, casting temperature, initial ground temperature field and phase-change effect were considered and the nonlinear finite element method was adopted to give the numerical results. For a practical bridge structure with cast-in-place concrete pile group foundation that was built in permafrost in Qing-Tibet plateau, the temperature field of refreezing process of ground is analyzed, and some significative conclusions on the problem were drew out. For the temperature values along body of the pile varying with the depth, the calculated values are compared with measured values in the scene, which illustrates the process and results in this paper are basically credible.