COUPLED HYDRO-THERMO-MECHANICAL PERIDYNAMIC MODEL FOR CONCRETE FREEZING FAILURE

Under low temperatures, the freezing of internal pore liquid water in concrete as a porous medium material leads to expansive deformation, which induces damage or even failure. To investigate the freezing damage process and mechanism, this study proposes a coupled hydro-thermo-mechanical model in integral form that can describe the freezing behaviors of concrete by applying peridynamic method, and develops a corresponding multi-rate explicit solution scheme. The numerical results of three-dimensional concrete specimens show that the temperature and pore liquid water pressure are in good agreement with the finite element results. In addition, the effect of permeability on the mechanical properties and damage behavior of concrete during freezing is investigated, and the results show that the permeability has a greater influence on the freeze-thaw resistance of concrete structures. When the permeability is higher, the pore liquid water pressure, crystallization pressure and freezing strain decrease, and the specimens have fewer cracks, and the degree of overall damage is reduced accordingly. The model can provide the basis for damage analysis of concrete under freeze-thaw cycles.