混凝土中氯离子三维扩散模型及参数拟合

提出了基于ANSYS有限元分析和试验实测数据拟合的混凝土中氯离子三维非稳态扩散模型.该模型可以模拟混凝土与海水接触表面氯离子随时间变化的累积效应、氯离子扩散系数随时间和氯离子浓度的变化,以及氯离子反应率对扩散的影响.根据非稳态扩散方程与导热方程的相似性,用ANSYS有限元软件参数化设计语言编程方法,实现了数值模拟分析;利用ANSYS的优化设计功能,以有限元数值计算结果与实测数据的误差平方和最小为优化目标,拟合氯离子扩散试验的实测数据,得到数值模拟所需的模型参数.计算表明:模型能比较好地拟合长期海洋环境暴露试验的实测数据,为海洋环境中使用的混凝土结构的耐久性设计提供参考依据.

A 3D Model of Chloride Ion Diffusion in Concrete and Determination of Its Parameters

In the present paper, a 3D model of chloride ion diffusion in concrete was proposed. The model was capable of capturing the effects of the time dependent variation of surface chloride ion concentration, chloride ion diffusivity coefficient variation with time and chloride ion concentration, and the effects of reaction rate of chloride ion. It was numerically implemented by using the finite element analysis software ANSYS and programming with the ANSYS Parametric Design Language, based on the similarity of unstable diffusion equation and the heat conduction equation. The model parameters can be determined by fitting the chloride ion distribution data obtained in diffusion experiments by the minimal square root of the error difference between numerical results and experimental data using the ANSYS optimization function. The model fits well with the chloride ion distribution data in concrete under long term marine exposure and serves as a good reference to the duration design of concrete structures used in marine environment.