混凝土中早期氯离子迁移混沌特征评价

Assessment of Chaos in the Early Transport of Chlorine Ion in Concrete

目的探索混凝土材料中早期氯离子迁移的混沌特征,以及迁移过程中时间序列的Lyapunov指数的计算,评价混凝土内部氯离子扩散的非线性特征.方法将养护28 d的100 mm×100 mm×100 mm规格混凝土试样浸泡于质量分数为4%的NaCl溶液中,30 d中每日分别在试件上钻芯抽取混凝土试样中0～3 mm,3～6 mm部位的粉末,根据我国建材行业标准JC/T420方法,测试粉末中的氯离子质量分数,按时间序列试样测试,根据混沌理论中的Lyapunov指数计算方法,分别求出空白C30混凝土试样中3～6 mm部位、复掺掺合料C50混凝土中0～3 mm,3～6 mm部位的早期氯离子迁移的特征.结果计算表明C50混凝土0～3 mm表面部位的Lyapunov指数为负数,不属于混沌特征范围,C30和C50混凝土试样中3～6mm部位的Lyapunov指数为正数,表现出良好的混沌特征.短期预测的结果精度满足要求.结论采用混沌理论分析评价混凝土中早期氯离子迁移特征是有效的,测试过程中选择合理的部位和嵌入维数是十分必要的.

This paper aimed to explore chaos in the early transport of chlorine ion in concrete, calculated Lyapunov exponents of time series of the transport of chlorine ion in concrete and assessed＇ the nonlinearity of chloride diffusion in internal of concrete. After conserved quintessentially 28 d,the 100 mm ×100 mm ×100 mm size concrete sample was bathed in the Nacl solution that 4% of the concentration of the quality percentage NaCl solution. In 30d time, we use electric drill to get the concrete powder from the 0 - 3 mm and 3 × 6 mm deep parts of concrete samples every day. According to JC/T420 methods of China building materials industry standards, we test the chlorine ion concentration of concrete powder. By the consequence of testing, we calculate Lyapunov exponents of time series of the transport of chlorine ion in C30 concrete powder from the parts whose depths is 3 -6 mm, and respectively calculate Lyapunov exponents of time se- ries of the transport of chlorine ion in C50 concrete powder from the parts whose depths is 0 - 3 mm and 3 6 mm. The result showed that Lyapunov exponents of 0 - 3 mm deep parts of C50 concrete are below zero, do not belong to the chaotic character range. The Lyapunov exponents of 3 -6 nun deep parts of C50 concrete and C30 concrete, are above zero,it means their time series system of the transport of chlorine ion in concrete belong to the chaotic character range. The forecast in short time distance meet the requirement of precision. Using the chaos theory to analysis and evaluation the early transport of chlorine ion in concrete is effective. It is very necessary to select the rational test parts and embedding dimension.