基于机电阻抗技术的锚固结构锈蚀监测与评估方法研究

In geotechnical engineering, corrosion is the major cause for deterioration in structural reliability of anchorage structures. Since anchorage structures are elusive and the corrosion issues are complex, there are few reports on corrosion monitoring of these structures at home and abroad. In order to solve such issue, a novel corrosion monitoring method for anchorage structures is proposed based on the coupled electro-mechanical impedance (EMI) of piezoelectric patch-corrosion coupon. The principle of the method is that the EMI technique is very sensitive to minor damage and corrosion induces mechanical impedance change in ferrous material. Experimental exploration is the major focus of this project, with the help of theoretical analysis and numerical simulation. Firstly, the theoretical and numerical models of the sensing mechanism of the coupled electro-mechanical impedance EMI of piezoelectric patch-corrosion coupon are established, which relate the electric impedance response of the piezoelectric patch to the thickness loss of the corrosion coupon. Then, the effects of temperature and humidity on the response of the sensor are investigated and the corresponding compensation methods are studied. Finally, the relationship between impedance response and thickness loss of the corrosion coupon is explored experimentally. The remaining strength and service life of the anchorage structures are estimated by the remaining thickness of the rock bolt or anchorage tendon. The results of this project will provide new insight in the real time monitoring and quantitative analysis of corrosion of anchorage structures, and provide technical support for the safe operation of anchorage structures.

在岩土工程领域，锈蚀是导致锚固结构耐久性劣化的最主要原因。由于锚固结构的隐蔽性和锈蚀问题的复杂性，目前国内外关于其锈蚀监测的研究报道较少。为了解决当前锚固结构锈蚀缺乏有效监测手段的难题，本项目充分利用机电阻抗法对细微损伤的敏感性和锈蚀引起铁质材料机械阻抗变化的特性，提出一种基于压电片-锈蚀试片机电阻抗耦合作用机理的锈蚀监测新方法。本项目将采用试验研究为主，理论分析及数值模拟相结合的研究方法；首先，建立压电片-锈蚀试片耦合系统的机电阻抗传感机理模型，构建压电阻抗响应与锈蚀试片失厚量之间的关系；其次，在不同的温度和湿度环境因素下研究该锈蚀传感器的响应及其补偿方法；最后，通过试验研究获取阻抗响应与锈蚀试片失厚量的关系，并基于剩余厚度估算锚固结构的剩余强度和剩余使用寿命。本项目研究成果将为在线监测并定量评估锚固结构锈蚀提供新思路，为保障锚固工程结构的安全性提供技术支撑。

针对锚杆锚固结构锈蚀监测的难题，提出基于压电片-锈蚀试片压电阻抗的锈蚀传感机理与方法研究，探索一种应用于锚固结构的新型锈蚀传感器及监测评估方法。首先，依据电弹理论及薄板弯曲理论，推导压电片-锈蚀试片压电阻抗响应与锈蚀失厚量之间的理论关系，为锈蚀传感机理提供理论依据。其次，利用有限元数值模拟进行压电片-锈蚀试片复合板压电阻抗的谐响应分析与模态分析，对压电片的压电参数、几何参数及材料参数和锈蚀试片的几何参数及材料参数进行参数化分析，为传感器优化提供依据。然后，制作锈蚀传感器原型，进行传感器防水材料选型试验、封装及加速锈蚀试验、以及温度影响试验共三组试验，研究电导峰值频率偏移与质量损失之间的关系，分析温度变化对传感器阻抗响应的影响，为锈蚀传感器的实际应用提供技术支撑。最后，搭建锚杆锚固结构锈蚀监测平台，实现传感器在实际工况下的应用，结合传感器峰值频率偏移和质量损失率之间的关系，评估锚杆锈蚀程度。本项目研究成果将为在线监测并定量分析锚固结构锈蚀提供新思路，为保障锚固工程结构的安全性提供技术支撑。