严酷水环境下化学植筋界面粘结性能的劣化机理和时变模型研究

For the chemical anchorage technology is commonly used in concrete structure reinforcement, a lot of researches on the interfacial adhesion performance have been attracted, which is the core and key of the chemical anchorage system, furthermore, the interfacial adhesion performance under harsh water environment will be exhaustively researched in this study. Firstly, against the lack of the existing bond-slip constitutive model, cohesive zone model of chemical anchorage bonding interface is proposed, and the measuring apparatus and method of the interfacial cohesive bonding parameters is designed, and then the numerical simulation method is employed to establish the FEM model of the cohesive zone model, and the reasonableness of which will be verified. Secondly, degradation rules of the interfacial adhesion properties under the harsh the water environment are researched, and also the loss proportion and damage rate. Combined with microscopic test and theoretical analysis, the deterioration mechanism of interfacial bonding properties will be studied, and the design method of chemical anchorage used in hydraulic concrete structure will be proposed considering service environment. Based on the researches of cohesive zone model and deterioration mechanism, the time-varying model of cohesive parameters will be established, such as bond strength and fracture toughness. And the time-varying model of each parameter will be merged to establish the time-varying constitutive model of the bonding interface. The feasibility of the proposed building method of time-varying constitutive model will be verified under typical environments, such as freezing and thawing. Finally, the failure mechanism of the bonding interface of under harsh water environments can be revealed, furthermore, the long-term service reliability evaluation theory of the chemical anchorage can be improved.

化学植筋是混凝土结构除险加固常用修复技术，其界面粘结性能作为受力的核心和关键，一直是研究人员关注的热点和难点，本项目重点研究严酷水环境下化学植筋的界面粘结性能。针对已有粘结-滑移本构关系的不足，研究构建化学植筋粘结界面的内聚力模型，设计测定内聚力模型参数的装置和方法，建立内聚力模型的数值模拟方法，并验证其合理性。研究严酷水环境下界面粘结性能的退化规律、劣损比例和损伤速率，结合微观测试和理论分析等，揭示界面粘结性能的劣化机理，提出考虑水工混凝土结构服役环境的化学植筋设计方法。基于内聚力模型和劣化机理的研究成果，研究内聚力模型中各参数的时变特性，建立各参数时变模型的融合方法，提出化学植筋粘结界面时变本构模型的构建方法，构建冻融等典型环境下的时变本构模型，验证方法的可行性。本项目的研究对揭示化学植筋粘结界面在严酷水环境下的失效机理具有重要意义，可进一步为化学植筋的长期服役可靠度评价提供理论基础。

为研究不同劣化环境下化学植筋承载力退化规律，进行了混凝土基材劣损、室内环境、室外环境、淡水环境、盐水环境、持续荷载作用以及耦合环境等多种环境下的化学植筋单筋拉拔试验，试验结果表明：混凝土基材的劣损对化学植筋承载力有着较为显著的影响；室内干燥环境和无腐蚀性水环境下，化学植筋承载力短期几乎没有劣化；经受自然环境温度变化和雨水侵蚀，化学植筋承载力在短期内仍有不同程度的劣化；氯离子对化学植筋的界面粘结性能影响较大，盐水环境下化学植筋短期内的承载力劣化明显；持荷条件下，无论在淡水环境和盐水环境下，化学植筋承载力在短期内均出现了较为明显的劣化；总的来讲，在进行既有混凝土基础上化学植筋设计或承载力评估时，需充分考虑上述显著劣化环境的影响。.与此同时，基于ABAQUS的双线性内聚力模型，利用弹性粘结应力理论分析了单筋拉拔过程中各个阶段粘结应力与界面滑移值的解析解。结合弹性阶段和弹性-屈服阶段的解析解，推导了内聚力模型各参数的表达式，为内聚力模型数值模拟的参数选取提供了理论依据。通过内聚力模型数值模拟结果与试验结果的对比，验证内聚力参数确定方法的正确性。在单筋拉拔试验和数值分析基础上，通过ABQUS软件的二次开发，根据不同环境下化学植筋承载力退化规律统计分析结果，将劣化时间t作为影响因素，提出了胶混粘结界面劣化内聚力模型的构建方法，并初步编制了相应的子程序。通过将数值模拟结果与四点弯曲梁的试验结果对比，验证了所开发程序的正确性和适用性；此外，构建了充分考虑混凝土损伤与胶混粘结界面劣化的化学植筋数值模型。