Numerical Simulation of Degradation Behavior of Concrete Piles in Sulfate Saline Soils

In this study, an integrated numerical approach is developed to simulate the damage and degradation behaviors of concrete piles in sulfate saline soils. The governing equations for modeling the sulfate diffusion-reaction mechanism are presented. The diffusion properties of sulfate ions are modified by taking into account the effects of pore filling and expansion cracking on the diffusivity of sulfate ions. The model for simulating the volumetric expansion and damage evolution is presented. The developed numerical method is verified by comparison with experimental results of linear expansion. Numerical analysis results show that the sulfate concentration tends to increase with the exposure time at the same diffusion depth, but the growth rate gradually slows with increasing diffusion depth. The concentration of the reacted calcium aluminates increases gradually with the exposure time, while reduces with the increasing diffusion depth. The effective diffusion coefficient decreases sharply at the interface depth, and then increases gradually with an increase in diffusion depth at the same exposure time. The higher environmental sulfate concentration and water-cement ratio can accelerate the degradation of structural capacity of concrete piles.