自然与人工模拟环境中环境-荷载耦合作用下混凝土结构氯盐侵蚀相似性研究

Durability deterioration of concrete structure caused by chloride ingress is a serious problem. The existing research results can’t be used to accurately evaluate the durability and forecast the useful life of concrete structure, which is due to the assumptions of the research inconsistent with practical situation. In addition, the influence of the coupled environment-load action unreasonably simplified and overlooked is another reason. Therefore, this project will research the damage characteristic of concrete microstructure by fractal theory, and the numerical simulation method is employed to investigate the damage of concrete microstructure. At the same time, the influence of the coupled environment-load action on the chloride ingress in concrete structure will be discussed, and the corresponding mechanism of chloride ingress in concrete structure will also be modeled. Through analyzing the differences and correlation of the concrete internal micro-environment and natural environment, the load effect caused by environment factors will be illustrated, and the models of the environment factors and its load effect will also be studied. Based on the equivalent standards, the unsteady environmental factors and its load effect will be quantified, and artificial simulation environment test method will be proposed with the precondition of the similar internal micro-environment response in concrete. Based on the similarity principle, the similarity of the chloride ingress in concrete structure under the coupled environment-load action in natural and artificial simulation environment will be investigated, which will provide important theory and technical support to evaluate the durability and forecast the useful life of the concrete structure in chloride environment.

氯盐侵蚀引起的混凝土结构耐久性退化问题严重；既有研究的假设和实际环境工况不符，且不合理地简化或忽视环境-荷载耦合作用的影响，导致研究成果难以准确地应用于混凝土结构耐久性评估与使用寿命预测。为此，本项目拟采用分形理论量化混凝土内部微细观结构损伤，提出混凝土内部微细观结构损伤的数值模拟方法，探讨环境-载荷耦合作用对混凝土氯盐侵蚀影响，构建环境-载荷耦合作用下混凝土氯盐侵蚀机理模型；通过分析自然环境与混凝土内部微环境间的差异和关联，阐释环境因素所引发的次生环境荷载效应，构筑环境因素及其荷载效应模型；依据等效准则量化环境因素及其荷载效应，基于混凝土内部微环境响应相似的前提，制订人工模拟环境试验制度；基于相似原理，研究自然与人工模拟环境中环境-载荷耦合作用下混凝土结构氯盐侵蚀相似性，为氯盐环境中混凝土结构耐久性评估与使用寿命预测提供重要技术支撑。

氯盐侵蚀导致混凝土结构而耐久性劣化是当前土木工程领域研究的焦点和难点，现有研究不合理地简化或忽视环境-荷载耦合作用的影响，导致研究成果难以准确地应用于混凝土结构耐久性评估与使用寿命预测。本项目开展了自然与人工模拟环境中环境-荷载耦合作用下混凝土结构氯盐侵蚀相似性研究，探讨了采用分形理论开展了混凝土内成分组成（粗集料）和缺陷等研究，建了自然环境因素作用谱和混凝土内微环境因素响应谱模型。通过研究混凝土的热膨胀系数和干缩系数变化，探讨了混凝土表层在环境因素作用下产生的环境次生荷载效应。通过分析荷载作用（压力荷载和拉力荷载）混凝土氯离子扩散系数变化规律，提出了考虑环境荷载效应的人工模拟环境试验制度。通过理论分析推导了混凝土氯离子侵蚀相似准则，开展了考虑环境荷载效应的混凝土氯盐侵蚀试验，研究成果为氯盐环境中混凝土结构耐久性评估与使用寿命预测提供重要技术支撑。