干湿交替下混凝土氯离子运输模拟

Modeling chloride penetration into concrete under drying-wetting cycles

在氯盐环境中,干湿交替区域是混凝土结构耐久性设计最为关键的区域。考虑水分在干燥和湿润情况下传输速度的差异,对干燥和湿润过程采用不同的扩散系数,建立了干湿交替下混凝土内水分传输的模型。并在此基础上建立了干湿交替情况下氯离子扩散和对流传输模型,并将上述模型在空间域和时间域离散,采用有限元方法求解。将数值模拟结果与解析解和试验结果进行对比,吻合的较好,验证了数值模型的准确性和可靠性。

In chloride environment, drying -wetting zones in concrete structures are key regions for durability design and assessment. In the present paper, the difference of the moisture transport into concrete structures during drying and wetting cycles is taken into account by adopting different moisture diffusivity in modeling moisture transport in concrete structures. In addition, an attempt has been made to develop model of chloride penetration into concrete under combined diffusion and convection mechanisms based on the transportation of moisture model . The governing equations of chloride ingress into concrete are described particularly and solved numerically by finite element analysis in time and space domains. The comparison among the results predicted by the present numerical model, analytical solutions and experimental tests are carried out to show the reliability and the effectiveness of the proposed numerical model.