氯离子在混凝土中双时变扩散分析研究  

Study on Double Time Varying Diffusion Analysis of Chloride Ion in Concrete

作　　者：赵辛玮 ZHAO Xin-wei(Shanghai Urban Construction City OperationCo.,Ltd.,Shanghai 200023,China)

机构地区：[1]上海城建城市运营(集团)有限公司,上海200023

出　　处：《中国市政工程》2022年第4期59-63,124,共6页China Municipal Engineering

基　　金：上海市科委基金资助项目(20DZ1202102,20DZ2251900,21DZ1203303,21002420100)。

摘　　要：氯离子侵蚀是除冰盐环境下混凝土结构耐久性劣化的主要原因。目前多采用Fick第二定律及一维稳态扩散模型对混凝土中的氯离子浓度进行预测与耐久性评价,但分析结果与实际氯离子侵蚀情况存在偏差。为更准确地描述氯离子扩散的时变规律,基于氯离子瞬态扩散理论和非稳态扩散方程,推导出前期时变与后期恒定的氯离子扩散系数模型的修正表观扩散系数公式以及表面氯离子浓度为指数及幂函数模型下的修正解析表达式,并与时变扩散有限元方法结合应用到实桥分析中,解析解与数值分析结果吻合较好,验证修正表观扩散系数与解析公式的正确性以及氯离子时变扩散有限元分析方法的适用性。Chloride ion corrosion is the main reason for the durability deterioration of concrete structures in deicing salt environment.At present,Fick's second law&1D steady-state diffusion model are mostly used to predict the chloride ion concentration in concrete and evaluate the durability.However,the analysis results deviate from the actual chloride ion erosion.In order to more accurately describe the time-varying law of chloride ion diffusion,based on the chloride ion transient diffusion theory and the unsteady diffusion equation,the modified apparent diffusion coefficient formula of the chloride ion diffusion coefficient model with time-varying and later constant and the modified analytical expression under the exponential and power function model of the surface chloride ion concentration are derived,and combined with the time-varying diffusion finite element method.The analytical solution is in good agreement with the numerical analysis results,which verifies the correctness of the corrected apparent diffusion coefficient and the analytical formula and the applicability of the finite element analysis method of chloride ion time-varying diffusion.

关 键 词：混凝土 耐久性 氯离子 FICK第二定律 时变扩散系数 

分 类 号：TU375[建筑科学—结构工程]