潮差区、浪溅区混凝土中的氯离子输运模型及仿真研究

Modeling and simulation of chloride transport in concrete in intertidal and splash zone conditions

潮差区、浪溅区处于干湿交替的复杂环境中,是腐蚀劣化最为严重的区域,直接影响着海工结构的耐久性和使用寿命。为了更好地描述潮差区、浪溅区的氯离子在混凝土中的侵蚀规律,本文采用Hamilton型变分原理建立氯离子的输运方程,结合细观角度,建立了一个有效的孔隙水饱和度的定量计算公式,并引入时间因素和孔隙水饱和度对非饱和状态下氯离子的扩散系数进行修正。利用有限单元法模拟氯离子在混凝土迁移过程,并与实验数据以及水下区氯离子的计算值进行对比验证。结果表明:模型计算结果和实验数据吻合较好,并且符合氯离子输运的一般规律。验证了本文提出的模型可以为潮差区和浪溅区混凝土结构的耐久性设计及服役寿命预测提供参考。

The intertidal and splash zones in dry-wet cycling complex environments are vulnerable to the most serious corrosion activity,which directly affects the durability and service life of maritime structures. In this study,we establish a model to describe the transport rule of chloride in concrete in intertidal and splash zone conditions. We based the chloride transport equations on the Hamilton principle and established an effective quantitative calculation formula to describe the degree of pore saturation based on the meso view. We modified the chloride diffusion coefficient by introducing a time factor and the degree of pore saturation. We simulated the migration of chloride in the concrete by the finite element method and compared the calculation results with the experimental data and the calculated value of chloride in the underwater zone. The calculation results agree well with the experimental data and conform to the chloride transport rule. These results prove that the model can provide a reference for durability design and for predicting the service life of concrete structures in intertidal and splash zone conditions.