基于桥梁耐久性的锈蚀钢筋力学性能“时变模型”构筑及宏观/微观机理分析

“Time-Varying Model” Construction and Macroscopic/Microcosmic Mechanism Study of Corroded Bar’s Mechanical Property Degradation Law Predicted Based on the Bridge Durability

摘要: 为了防止桥梁瞬时倒塌，本论文采用多种电化学检测手段，在快速精准测定钢筋锈蚀特征的基础上，结合有限元分析技术，深入揭示锈蚀钢筋的力学性能退化规律，构建因局部锈蚀引发的承载能力突变“时变模型”，据此对剩余寿命做出科学推断，实现服役桥梁耐久性的相对精准预测。首先，通过加速模拟锈蚀正交试验，建立“电化学信号–锈蚀速率”关系；再利用有限元技术构建基于多种电化学检测的钢筋锈蚀度与钢筋变形度的关系模型，把“电位信号–钢筋度–变形度”有效对应起来，并通过检测锈蚀断面的微观晶体结构，将外在宏观变形与材料内在微观结构相关联，深入揭示锈蚀钢筋在复杂应力状态下的应急反应机制及演化机理，构筑“电化学信号–锈蚀度–变形度–耐久性”时变模型，形成基于电化学信号的快速诊断体统，以此为依据对服役桥梁做出类似于医学上“依据骨龄判断年龄乃至预测寿命”的耐久性预测体系，防患于未然。

Abstract: In order to avoid the bridge collapsing instantaneously, this project plans to adopt a variety of electrochemical detection methods to thoroughly reveal the mechanical property degradation law of corroded bars and build a “time-varying model” with mutational carrying capacity resulted from a local corrosion, based on the rapid and accurate determination of rebar corrosion characteristics and the finite element analysis technology, and then accordingly scientifically infer the residual life to obtain an relatively precise prediction of the durability of bridge in active service. Building the relationship between “ECL signals and corrosion rates” through the orthogonal experiment of accelerated simulating corrosion to further revise the theoretical computational model built in the pre-research; then build a relational model between the rusting degree and deformation degree of rebar based on a variety of electrochemical detections by adopting the finite element analysis technology to effectively correspond the “electric potential signal-rebar degree- deformation degree” and thoroughly reveal the emergency response mechanism and the evolution mechanism of corroded bars under a complex stress; by detecting the micro crystal structure of the corrosion section to connect the external macroscopic deformation and material’s internal microstructure and finally build a time-varying model of “electrochemical signal-rusting degree- deformation degree-durability” and form a rapid diagnosis system based on the electrochemical signal. On this basis, form a durability prediction system which is similar to a medical judgment “judge the age or even predict the life span based on the bone age” to nip the instantaneous collapse in the bud.