基于线性增量的混凝土表面氯离子浓度预测模型  

A Prediction Model for Concrete Surface Chloride Ion Concentration Based on Linear Increment

作　　者：彭建新[1] 蔡明文[1] 张建仁[1] 胡守旺[1] 刘扬[1] 

机构地区：[1]长沙理工大学土木与建筑学院,湖南长沙410114

出　　处：《公路交通科技》2015年第12期94-99,107,共7页Journal of Highway and Transportation Research and Development

基　　金：国家重点基础研究发展计划项目(九七三计划)(2015CB057701);国家自然科学基金项目(51178060;51378081);交通运输部主干学科应用基础研究项目(2014319825160);湖南省教育厅优秀青年项目(15B015);湖南省研究生创新省级项目(CX2015B344)

摘　　要：基于Fick第二扩散定律,综合考虑了混凝土初始表面氯离子浓度以线性方式变化、扩散系数随时间不断减小以及温湿度对氯离子扩散的影响,把氯离子扩散过程分为两个阶段,推导得到一个新的氯离子扩散方程,结合现有数据,对理论数学模型进行了验证。结果表明：随着表面氯离子浓度以线性积累速率的减慢,短期内氯离子扩散过程也变得缓慢;阶段一与阶段二时间结合点处的两个氯离子曲线分布得到很好的吻合,用新方程所得到的氯离子分布曲线与以往普遍采用基准方程得到的分布曲线也能很好地匹配,在分别计算10 a,25 a,50 a混凝土中钢筋表面氯离子浓度到达锈蚀临界浓度时,用新方程比采用基准方程时要提前约3%-14%,且随着时间的增长二者之间差异不断减小。Based on the Fick＇s second law of diffusion,we divided the chloride ion diffusion process into 2stages when taking an overall consideration to the influence of variation of chloride concentration in initial surface of concrete in a linear way,decrease of diffusion coefficient with time and temperature and humidity on chloride ion diffusion. On this basis,a new chloride ion diffusion equation is derived. Combing with the existing data,the theoretical model is verified. The result shows that（ 1） as the linear accumulation rate of the chloride ion concentration in the surface slows down,the chloride ion diffusion process also becomes slowly in the short term;（ 2） the distributions of the 2 chloride curves at the combining point of stage one and stage two is well fit,and chloride ion distribution curve obtained by the new equation is well matched with the previous one obtained by widely used benchmark equation;（ 3） when the calculating result of chloride ion concentration on reinforcement surface in concrete of 10,25 and 50 years tending to critical concentration of reinforcement corrosion,adopting the new equation is about 3%- 14% in advance compared to adopting the benchmark equation,and the difference between them decreases as time goes.

关 键 词：桥梁工程 混凝土 线性增量 扩散方程 表面氯离子浓度 

分 类 号：U416.216[交通运输工程—道路与铁道工程]