电势条件对混凝土结构电化学修复数值模拟的影响

通过试验研究和理论分析，对比3类电势条件（常电势条件、电中性条件和高斯定理）对混凝土结构电化学修复过程数值模拟结果的影响. 利用物质守恒定律、Nernst-Planck方程和电势条件构建电化学修复过程的数值模型，通过数值模型比较电化学修复过程电势、氯离子浓度、净电荷数和电流密度等参数在混凝土内部的分布. 结果表明，在常电势条件下，除氯前端的氯离子浓度梯度较大；当采用电中性条件与高斯定理时，模拟氯离子浓度分布和电势分布结果较为相似，混凝土分别在辅助阳极与阴极钢筋区域形成电迁移加速作用区与抑制作用区. 试验研究电化学除氯过程的氯离子浓度分布. 试验结果与数值模拟结果的对比表明，采用电中性条件或高斯定理模拟氯离子浓度分布更接近试验测试结果，适用于钢筋混凝土结构电化学修复的仿真分析.

Effect of electric potential condition on numerical simulation of electrochemical rehabilitation for concrete structures

Three kinds of electric potential conditions, including constant potential condition, electro-neutrality condition and Gauss’s law, were employed to study their influence on the numerical simulation of the electrochemical rehabilitation for concrete structures. A numerical model was established based on mass conservation, Nernst-Planck and electric potential condition equations. The electric potential, chloride concentration, net charge and current density distributions in the concrete during the electrochemical rehabilitation were compared by numerical models. Results show that the chloride concentration gradient at the chloride wave front was moderately large for the constant potential condition model. Meanwhile, the modelling results of the chloride ion concentration and potential distributions from the electro-neutrality condition and the Gauss’s law models were similar. The acceleration area and the restricted area of the migration occur at the auxiliary anode and cathodic steel bars, respectively. The chloride ion concentration distribution was also experimentally obtained. The comparison of experiment results and numerically modelling results indicates that, the chloride ion concentration distribution of the electro-neutrality condition and the Gauss’s law models are more approximate to the experimental results. Therefore, the electro-neutrality condition and the Gauss’s law models are applicable for the simulation analysis of electrochemical rehabilitation for concrete structures.