饱水混凝土氯离子侵蚀数值试验随机细观分析

发布时间：2018-08-03 17:50

【摘要】：为研究饱水状态混凝土中氯离子侵蚀的规律,首先基于Fick第二定律,在前人研究的基础上推导出综合考虑混凝土劣化、荷载作用、混凝土对氯离子的结合作用、温度、混凝土内部相对湿度、氯离子扩散的时间依赖性、离子静电场作用和表面氯离子浓度影响的新扩散方程。然后针对氯离子侵蚀的随机性,建立混凝土随机细观模型,并将氯离子侵蚀宏观数值模型与混凝土随机细观模型融合,提出混凝土氯离子侵蚀的随机细观研究新方法。通过编制相应的MATLAB程序,可生成任意骨料含量并满足不同级配要求的随机混凝土试件,并编制程序将MATLAB生成的.fig格式图形文件转换为通用的.dxf格式,以便于建立的模型可被有限元软件调用。最后,通过对105个混凝土随机试件进行氯离子侵蚀数值试验模拟,采用概率和数理统计的研究方法,总结出混凝土中氯离子侵蚀的一般规律。研究结果表明:细观层次上的物质传输浓度分布和数值上与宏观层次都有显著区别,氯离子在混凝土中的传输具有显著的随机性,相同骨料含量的混凝土试件在同一深度的氯离子含量是随机变量,骨料对氯离子传输具有显著的阻碍作用,骨料改变了氯离子在混凝土中的传输路径,氯离子分布在骨料周围有绕流现象,试件某一深度处的氯离子浓度近似服从正态分布。
[Abstract]:In order to study the law of chloride ion erosion in saturated concrete, firstly, based on the second law of Fick, the comprehensive consideration of concrete deterioration, load, the binding action of concrete to chloride ion and the temperature are deduced based on the previous research. The new diffusion equation of the relative humidity of concrete, the time dependence of chloride diffusion, the effect of electrostatic field and the concentration of chloride on the surface of concrete. According to the randomness of chloride ion erosion, the stochastic meso model of concrete is established, and the macroscopic numerical model of chloride ion erosion is combined with the random mesoscopic model of concrete, and a new stochastic meso study method for chloride ion erosion of concrete is proposed. By compiling the corresponding MATLAB program, random concrete samples with arbitrary aggregate content and different gradation requirements can be generated, and the program is compiled to convert the graph file generated by MATLAB into the general .dxf format. The model can be called by finite element software. Finally, the general law of chloride ion erosion in concrete is summarized by means of probability and mathematical statistics through numerical simulation of chloride ion erosion on 105 random concrete specimens. The results show that the distribution and numerical value of mass transport concentration at meso level are significantly different from those at macro level, and the transport of chloride ions in concrete has remarkable randomness. The chloride content of concrete specimens with the same aggregate content at the same depth is a random variable, and the aggregate has a significant hindering effect on chloride ion transport, and the aggregate changes the transport path of chloride ion in concrete. There is a flow around the aggregate and the concentration of chloride ions at a certain depth of the specimen is approximately normal distribution.
【作者单位】：长安大学旧桥检测与加固技术交通行业重点实验室;中交第一公路勘察设计研究院有限公司;陕西省交通规划设计研究院;
【基金】：交通运输部应用基础研究项目(2013 319 812 100) 国家自然科学基金项目(51508027)
【分类号】：TU528

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