中文摘要：

混凝土二维扩散分析的有限元法等常用数值法通常需要在空间域和时间域中同时采取细密的离散网格，计算量大。针对混凝土中氯离子二维扩散问题，提出了计算长度的概念及其计算表达式，首次建立了相应的边界元计算方法，确定了时间域离散的步长。通过该计算模型研究了混凝土结构的拐角等几何形状复杂位置的氯离子分布规律。由于边界元法可以将二维问题简化为一维离散问题，而且该计算模型在时间域内的离散网格非常稀疏，因此，相对于其他数值方法，该方法计算量很小，算例分析验证了该方法具有很高的计算精度和计算效率。同时，对角点等位置的氯离子浓度的计算结果表明，二维方法能够更准确地反映氯离子在混凝土结构中的扩散和积聚规律。

英文摘要：

The conventional numerical methods, e.g., the finite element method （FEM） for chloride diffusion in concrete, usually require discretization of both the spatial and the time domain, yielding a great deal of unknowns and requiting much computational time. This paper presents the boundary element method （BEM） for two-dimensional chloride diffusion in concrete and the concept of computing length of the diffusion field with a computing expression. The displacement model of the linear boundary element is proposed, in which the time domain is discretized into just four subdomains, while the spatial domain is discretized along the boundary of the computing diffusion field, so that fewer unknowns are produced and little computing time is required. An example is given to demonstrate the accuracy and efficiency of the presented method. Furthermore, the distribution of chloride concentration near the intersection of the exposed surface and the diagonal is increasing, which shows that the two-dimensional analysis of chloride diffusion can reflect the real aspects of chloride diffusion and concentration in concrete structures, compared with the one-dimensional analysis methods.