季冻区盐冻作用下结构氯离子侵蚀耐久寿命预测

Prediction of the durable life of prestressed concrete structures eroded by chloride ions under salt freezing in seasonally frozen areas

为了预测季冻区盐冻作用对预应力混凝土结构耐久性的影响,本文进行了混凝土盐冻损伤、氯离子扩散系数和结构耐久寿命的研究。根据中国季冻区主要城市的环境温湿度和混凝土冻融试验数据,分析了混凝土在盐冻环境下的损伤度;考虑混凝土盐冻循环损伤的影响,建立了预应力混凝土结构中氯离子时变扩散系数模型;采用Monte Carlo模拟分析了四个参数对预应力混凝土结构盐冻环境下氯离子侵蚀耐久寿命的敏感性;使用Matlab中JC算法,预测了盐冻作用下氯离子侵蚀预应力混凝土结构耐久寿命。结果表明:中国华北季冻区结构氯离子侵蚀耐久寿命最短,且混凝土表面氯离子浓度是影响耐久寿命的最敏感参数。

This study sought to predict the damaging effect of salt freezing on a prestressed concrete structure′s durability in a seasonally frozen area using analyses of the diffusion coefficient of chloride ions and the structure′s durable life.The degree of damage to the concrete in the salt freezing environment was analyzed using temperature and relative humidity data from the cities in the seasonally frozen areas of China and data from the concrete freeze-thaw test.A time-dependent diffusion coefficient model for chloride ions in prestressed concrete structures was established,taking into account the damage of the salt freezing cycle on concrete.The Monte Carlo simulation was used to investigate the sensitivity of four parameters to the durable life of prestressed concrete structures exposed to chloride ions under salt freezing conditions.The durable life was predicted using the JC algorithm in Matlab.Results showed that the structure′s durable life,subject to chloride ion erosion,was shortest in the North China seasonally frozen area,and the concentration of chloride on the structure′s concrete surface was the most sensitive parameter affecting its durable life.