冻融循环下海工预应力混凝土结构的耐久性

Durability for Marine Pre-stressed Structures with Freezing-Thawing Cycles

从冻融与氯盐侵蚀机理出发,分析了影响预应力混凝土结构耐久性的主要因素;通过试验,测定了不同冻融条件下的氯离子扩散深度.以预应力混凝土氯离子扩散模型为基础,综合考虑冻融损伤、氯离子扩散系数的时间依赖性等因素,建立冻融条件下预应力混凝土结构氯离子扩散模型,并采用Crank-Nicholson格式差分进行数值模拟,运用实测数据验证了模型的正确性.结果表明:冻融循环是引起混凝土破坏的动力;应力水平加速了混凝土的损伤与劣化过程;水化龄期的选取对提高氯盐侵蚀下的混凝土结构耐久性起着非常重要的作用.

Based on the mechanism of chloride subsiding with freezing-thawing damage, the major factors influencing durability and chloride permeation depth with freezing-thawing were analyzed and measured by tests. Aimed at chloride diffusion equation for pre-stressed structure, which considered freezing-thawing damage and time dependence of diffusion coefficients, the model of chloride diffusion for marine prestressed concrete structure in freezing-thawing and chloride damage was deduced, which was analyzed by numerical simulation of finite difference method in the form of Crank-Nicholson. The testing data validated the model correctness. It is discovered that freezing-thawing cycle is the driving force to concrete damage and the process of damage and deterioration for concrete is accelerated by stress level. It is found that age is essential to durability of chloride-resistant.