疲劳荷载-环境耦合作用下沿海混凝土结构锈裂行为的多尺度分析

This project explores the key scientific issues of coastal concrete structures cracking due to corrosion expansion. Firstly, coupled effect of fatigue loading and environment is considered comprehensively by correctly simulating the real working condition of coastal reinforced concrete. The structural model of interfacial transition zone between corroded steel bars and concrete which can reflect the physical chemistry essence of corrosion layer is established in micro-scales. The non-uniform distribution and evolution of corrosion layer is described in meso-scales. The size and distribution of concrete cover cracking is determined in macro-scales. Secondly, based on thermodynamics and porous medium theory, the chemo-mechanical equivalent transformation of corrosive effect is conducted. Then, by using multi-scale transition theory, the micro/meso structural characteristics of corrosion layer are implanted in macroscopic properties of concrete. The multi-scale damage model of concrete corrosion expansion cracking under coupled effect of fatigue loading and environment is established, forming a brand new multi-scale interaction based theory framework. Finally, the multi-scale simulation technique based on the second development of ABAQUS is studied. By establishing the scale-span calculation model of stress field in concrete, the whole damage evolution process of concrete cracking due to corrosion expansion under coupled effect of fatigue loading and environment can be simulated, thus providing theoretical instruction for the durability evaluation, life prediction and numerical simulation of concrete structure.

项目针对沿海混凝土结构锈胀开裂面临的关键科学问题进行探索。首先通过正确模拟沿海混凝土内钢筋锈蚀的实际工况，全面考虑疲劳荷载-环境耦合作用的影响，从微观尺度上建立反映锈蚀层物理化学本质的微结构模型，从细观尺度上描述锈蚀层的不均匀锈蚀特性及锈胀历程，从宏观尺度上确定保护层裂缝的分布和尺寸；其次基于多孔介质理论与热力学平台，实现锈胀效应的化学-力学作用等效转化，进而运用多尺度过渡理论，将界面锈蚀层微/细观结构特征植入其宏观性能，构建疲劳荷载-环境耦合作用下钢筋混凝土锈胀开裂的多尺度渐进损伤模型，形成崭新的基于微/细/宏观多尺度互动的混凝土结构锈裂行为理论框架；最后研究基于ABAQUS二次开发的多尺度数值模拟技术，建立混凝土内部跨尺度应力场数值计算模型，模拟疲劳荷载-环境耦合作用下钢筋混凝土锈裂损伤局部化形成、破坏扩展直至失效的完整演化过程，为混凝土结构耐久性评估、寿命预测及数值模拟提供理论指导。

我国沿海地区的桥梁及公路等基础设施，除了承受车辆等荷载作用外，还受到氯盐侵蚀的影响，来自疲劳荷载的交变应力和氯盐腐蚀介质的耦合作用将进一步加剧混凝土结构的耐久性失效；而要准确掌握钢筋锈蚀后引起的混凝土结构性能变化规律，就必须正确认识真实工况下钢筋的锈蚀特性及其所导致的混凝土锈裂规律。本项目针对沿海混凝土结构锈胀开裂面临的关键科学问题进行探索，内容包括：（1）开展了钢筋-混凝土界面锈蚀层结构在不同尺度上的分析表征，构建了疲劳荷载-氯盐环境耦合作用下钢筋混凝土锈裂行为的结构模型；（2）建立了钢筋锈蚀产物均匀/非均匀锈胀效应的化学-力学作用等效转化框架，并通过试验进行了验证；（3）将纳米压痕模拟得到的锈蚀产物弹性模量作为核心力学参数植入有限元模型，实现了疲劳荷载-氯盐环境耦合作用下钢筋混凝土的锈裂行为的多尺度模拟。研究成果可为混凝土结构耐久性评估、寿命预测及数值模拟提供理论指导。