混凝土中氯离子时变扩散的边界元分析

Boundary Element Method for Time-dependent Chloride Diffusion and the Chloride Distribution in Concrete

氯离子在混凝土中的扩散是一个时变过程。考虑氯离子扩散系数的时间依赖性,将时变扩散系数引入混凝土的氯离子扩散模型中,通过变量代换,给出了时变扩散条件下氯离子扩散方程的基本解,并基于误差函数建立了氯离子扩散场补偿长度理论,分析了散场补偿长度系数的取值,在此基础上建立了时变扩散系数下混凝土中氯离子扩散分析的边界元法。通过算例分析验证了氯离子扩散场补偿长度理论对于氯离子扩散分析的数值方法的合理性,证明了该法具有较高的计算精度和计算效率。

The process of chloride diffusion in concrete is time-dependent. The boundary element method （BEM） with a time-dependent diffusion coefficient is presented for chloride diffusion in concrete based on the suitable transformation of variables. The fundamental solution of the partial differential equation for time-dependent chloride diffusion in concrete is developed, and the compensation length of the diffusion field is defined as well as the compensation coefficient. The scheme of BEM with a time dependent diffusion coefficient is developed. Two examples are given to demonstrate the accuracy and efficiency of the presented method and the rationality and the importance of the compensation length for the method.