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

监测对保持桥梁、大坝、隧道等各种结构物的使用状态和延长其使用寿命具有重要作用。在开挖边坡、地下开挖等不确定因素较多的情况下，监测对安全施工至关重要。本文在光纤传感器的基础上，结合应变位移传感器的发展，提出了一种新颖的监测系统。在实验室和施工现场对该系统进行了测试，发现该系统可以适用于各种实际用途。以下是本研究的主要结论。光纤测量仪（FOG）是一种基于光纤布拉格光栅（FBG）传感器的应变测量模块，通过拉伸、弯曲和温度敏感性试验，阐明了光纤测量仪的力学特性。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。在光纤光栅传感器附着于氯乙烯管的基础上，又研制了光纤光栅光学位移装置（FODD）。光纤光栅传感器安装在管道的几个部分，每个部分安装三个传感器。FBG传感器的安装使FODD能够测量位移及其方向。采用样条插值和多项式插值获得连续位移。研究发现，当位移不单调时，采用固定间隔的光纤光栅传感器和样条法可以获得较好的位移测量效果。阐明了测量过程中源电压和数据传输光纤局部曲率的影响。应变位移监测系统是在各种基本考虑的基础上建立起来的。发现这一拟议的监测系统适用于较长时间的监测和远程控制测量。该监测系统有望应用于各种结构的安全控制。但是，与普通的电阻应变片相比，光纤的处理非常困难，因此需要开发合适的包装方法和对主光纤的制动的鲁棒性。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