非饱和状态下纤维混凝土氯离子传输及其理论模型

The durability of fiber reinforced concrete (FRC) has been the key for structure design with the wide use of FRC in engineering. In order to enrich the durability theory of FRC and improve its durability design level under marine environment, the behaviors of chloride transport in unsaturated FRC (serviced in tidal zone, splash zone and wetting-drying zone) are systematically studied in this object. The dynamic process of chloride solution transport in unsaturated FRC is continuously monitored by X-CT and the property of chloride transport in fiber-concrete interface zone is investigated by X-CT combined with Electron probe microanalysis (EPMA). Several experiments are designed to investigate chloride transport in FRC with constant and variable saturation degree. The feature and law of chloride transport in unsaturated FRC are explored and the synergistic mechanism of chloride diffusion and convection is also investigated. The theoretical models of chloride diffusion and diffusion-convection transport in unsaturated FRC are established based on porous media theory, composite material theory and multi-scale transition method; besides, the simulation results are verified by experiment results. This research is of great theoretical significance to the application of FRC in ocean engineering.

随着纤维混凝土工程应用领域的拓宽，其耐久性已成为结构设计的关键。为完善纤维混凝土耐久性理论，提高海洋环境下纤维混凝土耐久性设计水平，本项目以服役于海洋潮汐区、浪溅区、干湿交界处的纤维混凝土为对象，系统研究非饱和状态下纤维混凝土氯离子传输行为。首先采用X-CT连续追踪氯盐溶液在非饱和纤维混凝土中的动态传输过程，并结合电子探针显微分析技术揭示纤维-混凝土界面氯离子传输特性；设计相关试验探究非饱和纤维混凝土饱和度恒定、动态变化时的氯离子传输，掌握非饱和纤维混凝土氯离子传输特点与规律，探明氯离子扩散、对流传输交互作用机制；基于多孔介质理论、复合材料理论和多尺度过渡方法，建立非饱和纤维混凝土氯离子扩散传输、扩散-对流传输理论模型，并通过试验予以验证。该研究为纤维混凝土在海洋工程中的应用奠定理论基础。

随着纤维混凝土工程应用领域的拓宽，其耐久性问题也逐渐引起人们的重视，尤其是在海洋潮汐区、浪溅区和干湿交界处等非饱和情况下，混凝土的有害介质传输决定了整体结构的耐久性与服役寿命，是工程结构设计的关键。为完善混凝土耐久性理论，提高海洋环境下纤维混凝土耐久性设计水平，本项目系统开展非饱和状态下纤维混凝土氯离子传输行为研究。掌握了纤维类型与掺量对饱和、非饱和混凝土（砂浆）氯离子传输性能的影响规律，建立了非饱和钢纤维混凝土氯离子扩散系数与纤维掺量的定量关系，揭示了钢纤维-砂浆界面性能及对氯离子传输性能的影响，构建了非饱和钢纤维混凝土氯离子扩散传输、扩散-对流传输数值模型。探明了非饱和砂浆饱和度恒定、动态变化时的氯离子传输特点与规律，并揭示了碳化作用对非饱和砂浆氯离子传输性能的影响，建立了砂浆氯离子传输系数与饱和度的定量关系，揭示了非饱和砂浆氯离子扩散、对流传输的交互作用机制。掌握了模拟海洋环境氯盐侵蚀下钢纤维混凝土力学性能演变规律，揭示了海洋水下区、潮汐区、浪溅区钢纤维混凝土氯离子传输特点与规律。本项目取得的学术成果对纤维混凝土在海洋等严酷环境中的工程应用具有重要的理论意义和指导价值。