Development of Advanced Fiber Optic Sensors and Their Application to Health Monitoring of Civil Infrastructures

监测对于保持桥梁、大坝、隧道等各种结构的使用状态，延长其使用寿命起着重要作用。在路堑边坡、地下开挖等不确定因素较多的情况下，监测对安全施工也是必不可少的。在这项研究中，结合基于光纤传感器的应变和位移传感器的开发，对一种创新的监测系统进行了评估。这一新提出的系统在实验室和施工现场进行了检验，发现该系统可以适用于各种实用目的。本文的主要研究成果如下：1.研制了基于光纤布拉格光栅(FBG)传感器的光纤陀螺应变计模块，通过拉伸、弯曲试验和温度灵敏度试验，对光纤陀螺的力学特性进行了研究。对应变和温度敏感性的澄清将光纤陀螺的应用扩展到更广泛的温度范围。Fib…在氯乙烯管道上安装光纤光栅传感器的基础上，研制了更多的光学位移装置(FODD)。FBG传感器安装在管道中的几个区段，每个区段有三个传感器。这种安装的FBG传感器使食品和药物管理局能够测量位移及其方向。采用样条法和多项式插值法来获得连续位移。结果表明，在位移不是单调的情况下，采用等间距布设光纤光栅传感器和采用样条法可以获得较好的位移测量效果，并分析了测量过程中电源电压和数据传输光纤局部曲率的影响。应变和位移监测系统是在各种基本考虑的基础上建立的。该监测系统不仅适用于较长时间的监测，而且还适用于远程控制测量。该监测系统有望应用于各种结构的安全控制，但与常规的电阻应变片相比，光纤的操作难度很大，因此需要开发合适的包装方法和对初级光纤制动的鲁棒性。较少

Monitoring plays an important roll to keep various structures such as bridge, dam and tunnel in service condition and to prolong their life. Monitoring is also essential for safe construction with many uncertainties such as cut slope and underground excavation. In this study, an innovative monitoring system is assessed together with the development of strain and displacement transducer on the basis of fiber optic sensor. This newly proposed system is examined in laboratory and a construction site and it is found that this system can be applicable for various practical purposes. The followings are main conclusions obtained in this study.Fiber Optic Gauge (FOG) is developed as a strain gauge module based on Fiber Bragg Grating (FBG) sensor and the mechanical characteristics are clarified by the tensile and bending test together with the temperature sensitivity test. Clarification of the strain and temperature sensitivity extends the application of FOG to a wider range of temperature. Fib … More er Optic Displacement Device (FODD) is also developed on the basis of FBG sensor attached to vinyl chloride pipe. FBG sensors are installed in the several sections in the pipe with three sensors in each section. This installation of FBG sensors enables FODD to measure displacement and its direction. Interpolation of Spline and polynomial is applied to obtain continuous displacement. It is found that a good displacement measurement can be attained by a constant interval allocation of FBG sensors and application of Spline method particularly when displacement is not monotonous.It is also clarified the influence of the source voltage during the measurement and the local curvature of the data transmission optical fiber. Strain and displacement monitoring system is established on the basis of the various fundamental considerations. This proposed monitoring system is found to be applicable for a longer period of monitoring and for remote-controlled measurement as well. This monitoring system is expected to be applied for various structures for their safety control.However, the handling of fiber optics is very difficult compared to the ordinal resistive strain gauges, so that the proper packing method and the robustness to braking the primary optic fiber should be developed. Less