基于荷载和海洋环境耦合作用的涂层混凝土损伤行为研究与寿命预测

Coating protective technology is an effective measure to ensure the long-term safe operation of marine concrete structures. The research on the damage of coated concrete is of important scientific value and engineering significance. At the beginning of the project, according to the theory research and engineering investigation, the institution of the accelerated damage test of coated concrete is established . By means of microcosmic-test to track the micro-evolution of chemical and condensed structures of concret, and integrating the real exposure test result, the law of coating degradation behavior is revealed. According to the bending load and marine corrosive factors collaborative, considering the internal relation of coating and concrete, and studying the quantitative relationship between the differences of the marine corrosive ion concentration and interfacial strength variation of coating and concret, the mechanism and critical strength of interface damage are obtained .The chloride transfer mode and steel bar corrosion time-variable law are explored based on the damage characteristics of tidal range area and splash zone afterwards. In accordance with coating degradation behavior, interface damage mechanism, chloride transfer mode and steel bar corrosion time-variable law abtained, based on fractal and artificial neural network theory, the service life prediction model of coated concrete structure is built. Finally, service life prediction model is verified and revised through the investigation of marine engineering damage, so that it would support the national marine infrastructure for long life service with theoretical and technical reserve.

涂层防护技术是保障海工混凝土结构长期安全运行的有效措施，研究涂层混凝土的损伤问题具有重要的科学价值和工程意义。本项目首先通过理论研究和工程调研，建立涂层混凝土加速损伤试验制度。借助微观试验跟踪涂层化学结构和凝聚态结构的微观演变，拟合实海暴露试验结果，揭示涂层劣化规律；针对弯曲荷载和海洋腐蚀因子耦合作用，考虑涂层和混凝土的内在相互联系，研究海洋腐蚀离子的浓度差异与涂层和混凝土之间界面强度的定量关系，获得界面损伤临界强度和损伤机理；根据海洋潮差区和浪溅区的腐蚀特点，探讨涂层混凝土的氯离子传输模式和钢筋锈蚀时变规律。根据获得的涂层劣化行为、界面损伤机理、氯离子传输模式和钢筋锈蚀时变规律，基于分形理论和人工神经网络理论建立涂层混凝土结构服役寿命预测模型；最后通过对服役中的海洋工程损伤调查，验证并修正服役寿命预测模型，为我国海洋基础设施超长寿命服役提供理论与技术储备。

弯曲荷载和海洋环境的复杂因素给混凝土结构带来严重的腐蚀破坏，表面涂层防护技术作为一种便捷有效的防护措施引起普遍关注。本项目通过研究氯化橡胶、聚氨酯（脲）和聚脲涂层砂浆在氯盐浸渍、海水冲刷单独作用以及分别与弯曲荷载耦合作用下的性能变化，得到了腐蚀不同时间后涂层宏观微观性能的退化规律；通过对涂层砂浆抗氯离子渗透性、附着力、电化学实验对涂层的防护效果进行了验证。涂层在氯盐浸渍和海水冲刷两种条件下的耐腐蚀性能研究表明：聚脲涂层耐腐蚀性能最佳，腐蚀后涂层力学性能和表面性能的退化规律从大到小为：氯化橡胶>聚氨酯（脲）>聚脲。氯盐浸渍和氯盐与弯曲荷载耦合两种条件下砂浆强度、抗氯离子渗透性和界面性能研究表明：无涂层和三种涂层砂浆试块抗折强度和涂层附着力均发生不同程度的下降。随腐蚀时间延长，试块氯离子含量增加，氯离子扩散系数降低并趋于平稳。氯盐与弯曲荷载耦合条件下的EIS研究结果表明：腐蚀后无涂层与三种涂层砂浆试块的低频阻抗模值|Z|0.01Hz、砂浆电阻Rm、电荷转移电阻Rct减小，其中聚脲涂层防护性能最佳。海水冲刷和海水冲刷与弯曲荷载耦合两种条件下砂浆强度、抗氯离子渗透性和界面性能研究表明：随腐蚀时间延长，无涂层砂浆试块和三种涂层砂浆试块抗折强度降低，涂层附着力减小，氯离子含量增加，氯离子扩散系数降低并趋于平稳。海水冲刷与弯曲荷载耦合条件下的EIS研究结果表明：腐蚀后涂层砂浆低频阻抗模值|Z|0.01Hz、涂层砂浆电阻Rm、电荷转移电阻Rct减小，涂层砂浆/钢筋界面电容Ydl增大。通过上述研究，以期达到延长跨海大桥、海底隧道、海港码头等重大海洋基础设施的服役寿命，保证其长期安全运行的最终目标。