基于自发漏磁的钢筋既有应力无损检测机理研究

It is of great practical significance to quantify and accurately obtain the existing stress of the steel bar inside the concrete for scientifically and objectively evaluating the safety of the bridge. In order to solve the problem that the existing stress measurement methods for reinforced concrete bridges are destructive or insufficient precision induced by vulnerable to environmental factors, the project proposes the new research ideas that the non-destructive testing of the existing stress of steel bar based on self-magnetic flux leakage. Based on the general theory of mechanical-magnetic coupling, this proposal reveals the constitutive relation between the mechanical behavior and magnetism of reinforced concrete beam. The spatial distribution characteristics of self-leakage flux leakage of reinforced concrete beams are studied under a constant load, and its evolution law is revealed with stress load, and then the effective criterion of stress detection of reinforced concrete beams is constructed. A numerical model for studying the evolution of self-magnetic flux leakage with stress evolution is established based on the constitutive equation of mechanical-magnetic coupling. The exact values of the coupling parameters for the constitutive equations are studied, and the quantitative inversion theory for existing stress of reinforced concrete beams is derived. The purpose of this project is to analyze the physical mechanism of the stress-magnetic coupling in the stage of elasticity and plastic deformation of steel, and to construct the theoretical model of stress detection of the reinforced concrete beam based on metal magnetic memory effect, and also to extract the characteristic parameters to evaluate the structural stress. The research findings would provide the theoretical basis and the technical support for the quantitative detection of the stress distribution of the reinforced concrete bridge, it has important scientific significance and application value.

量化、精准获取混凝土内钢筋既有应力对科学、客观评估桥梁的安全性具有重要的现实意义。针对现有钢筋混凝土梁桥应力检测手段存在破坏性或易受环境因素影响而导致检测精度不足的问题，本项目提出一种基于自发漏磁的钢筋既有应力无损检测的研究新思路。拟从力磁耦合一般理论出发，揭示钢筋和钢筋混凝土梁力磁耦合本构关系；研究恒载下钢筋混凝土梁自发漏磁场空间分布特征，揭示钢筋自发漏磁场随应力负载演化规律，构建混凝土梁内钢筋既有应力检测的有效判据。建立以力磁耦合本构方程为核心的研究自发漏磁场分布随应力演化的力磁耦合数值模型，研究本构方程中特征参数的确切取值，提炼钢筋既有应力定量反演理论。本项目预期剖析弹塑性形变钢筋自发漏磁场随应力演化规律，构建基于自发漏磁的混凝土梁内钢筋应力检测的理论模型，为定量检测钢筋混凝土桥梁真实应力分布提供理论基础和技术支撑，具有重要的科学意义和应用价值。

本项目针对现有混凝土桥梁内部钢筋应力无损量化检测手段缺乏、检测精度不足的问题，基于钢筋的力磁耦合特性，提出一种基于自发漏磁效应的混凝土内部钢筋应力无损检测新思路。针对钢筋力磁耦合本构关系不明确和定量解析模型缺乏等关键科学问题，系统、深入研究了混凝土内部钢筋的力磁耦合模型修正理论、钢筋自发漏磁场随空间分布规律和应力演化规律；揭示了混凝土桥梁内部钢筋磁导率和磁化强度在弹塑性形变区随应力的演化规律，提出了考虑钢筋磁滞效应的Jiles-Atherton力磁耦合修正模型；建立了基于钢筋漏磁场空间分布特征的“轴向漏磁场波动对数”和“面积偏移比参数”等力磁耦合量化指标，构建了基于漏磁场分布特征的量化检测钢筋既有应力水平的钢筋应力无损检测理论模型。为精准、量化检测钢筋混凝土桥梁应力状态提供了新的技术思路与理论基础，具有良好的应用前景。