滨海非饱和钢混结构中氯离子传输的数值模拟

Numerical simulation for chloride transport of nonsaturated R.C at coastal zone

为探究非饱和状态下钢混结构中氯离子质量分数的分布情况,定义容量矩阵、传递矩阵和氯离子通过率向量,并与瞬态热平衡方程中的各参量进行等效,给出了基于ANSYS热分析模块模拟非饱和混凝土中氯离子传输的数值方法,在验证方法有效性的同时,探究钢筋混凝土梁遭受单向、双向、三向侵蚀后梁内的氯离子质量分数分布规律.研究结果表明:数值模拟程序所得氯离子质量分数值与试验结果非常接近,非饱和混凝土氯离子传输的数值模拟方法有效;钢筋混凝土梁遭受单向侵蚀时混凝土中氯离子质量分数衰减的最快,双向侵蚀其次,三向侵蚀时氯离子质量分数衰减最慢;在遭受多向氯离子侵蚀时,箍筋及纵筋表面氯离子质量分数比单向侵蚀时大;受侵蚀的相邻截面越多,钢筋越容易锈蚀,且距离越近的截面对其影响越大;氯离子从3个方向侵蚀的计算结果略大于从两个方向侵蚀的计算结果,左侧氯离子在10年侵蚀时间内有部分通过梁宽方向传输至右侧,因此,在长时间的侵蚀作用下,受到多向侵蚀的钢混梁内钢筋的腐蚀情况更为严重.

Capacity Matrix, Transfer Matrix and Chloride Passing Rate Vector are associated with variables in transient heat balance equation, and a numerical simulation method by ANSYS thermal analysis module for chloride transport in nonsaturated concrete is proposed to investigate the chloride transport model in nonsaturated concrete. The numerical results are validated by experimental data. A R.C beam is corroded with chloride from three different directions, respectively. The results indicate that the chloride concentration by numerical simulation is very close to the experimental results. Numerical simulation provide another way for modeling chloride transport of nonsaturated concrete. For corrosion of R.C beam from single direction, the decay of chloride concentration is the quickest. The decay speed for corrosion from three directions is the slowest, and corrosion from two directions is in the middle. Corrosion from multiple directions leads to that the chloride concentration on the surface of rebar and stirrup is higher than single direction. Corrosion from multiple adjacent sections cause more easily rebars corrosion. The closer section will induce corrosion more seriously. Chloride transport to the right from the left of beam section within ten years, and the results of corrosion from two directions is a slightly more than that from three directions. Therefore, chloride penetration from multiple directions will induce more serious corrosion to the rebar in a long time.