基于导电性分析的湿热环境下CFRP-混凝土界面粘结性能退化规律研究

Carbon fiber reinforced polymer (CFRP) has been widely applied in concrete structures strengthening. The bonding deterioration between CFRP and concrete caused by the hygrothermal environment is extensively attracted. However, the approach which can quantitatively evaluate the interface damage has not been put forward. Former study shows that the electrical analysis technique could quantify the environmental effect efficiently and evaluate concrete behavior deterioration quantitatively. In this study, the electrical analysis technique will be utilized to quantitatively evaluate the bonding behavior deterioration. The moisture content in the interface will be measured and the influence of environment factors on the behavior and electrical conductivity of interface will be explored in meso scale. Firstly, the performance evaluation model of the interface material will be developed based on the electrical analysis theory, and the chemical components and porosity development law will also be considered in this study. Secondly, given the non-uniform environmental effects in civil structures, the evaluation method of interface bonding performance of CFRP-concrete in hygrothermal environment will be proposed from the macro scale. Finally, the long-term performance deterioration will be modeled based on multi-scale simulation. This project can provide theory and methods for long-term performance evaluation of CFRP strengthened concrete structures under hygrothermal environment, which has significant scientific and engineering values.

针对湿热环境引起的CFRP-混凝土界面粘结性能劣化这一耐久性问题，目前国内外学者虽有所关注，但考虑环境因素影响定量评估界面损伤的方法还未提出。申请人前期研究成果表明，基于导电性分析技术能简单快速有效地量化环境因素影响，定量评估混凝土材料性能退化。本项目拟进一步采用该技术对CFRP-混凝土界面损伤进行定量评估研究，具体内容包括: 1）测量界面含水率，量化分析环境因素对界面材料性能和导电性的影响，结合界面在湿热环境下的化学成分和孔隙变化规律，建立基于导电性分析的界面材料性能评估模型；2）考虑工程结构不均匀环境因素，应用该模型提出湿热环境下的CFRP加固混凝土结构界面粘结性能评估方法；3）基于导电性分析研究结果，模拟长期性能退化规律。本项目研究将为CFRP加固后的混凝土结构监测与性能评估提供技术手段，为CFRP加固结构的全寿命设计提供科学基础，具有重要的学术意义与工程价值。

针对湿热环境引起的CFRP加固混凝土结构界面粘结性能劣化这一耐久性问题，本项目研究了加固结构界面粘结性能的检测方法、退化规律、评估模型以及改善措施，提出了基于导电性分析的界面粘结性能检测方法，探索了界面含水率的估算模型并阐释了含水率对导电性和界面粘结性能的影响，通过导电性的差异不仅可以快速评估不同湿热作用下混凝土的力学性能变化，还可有效检测出CFRP-混凝土界面损伤的位置以及损伤大小；同时，通过有限元方法对加固后结构的界面剥离过程进行了模拟，采用离散元方法模拟了不同耐久性问题引起的混凝土结构开裂及长期力学性能演化规律。探索了不同水平预应力CFRP、端部预紧力与自锁机械锚固等不同方法防治CFRP加固结构界面劣化后的剥离破坏，取得了良好的效果。本研究将为CFRP加固后的混凝土结构检测与性能评估提供技术手段，为CFRP加固结构的全寿命设计提供科学基础。