分布式光纤传感技术在地铁隧道监测中的研究

发布时间：2018-03-30 04:34

本文选题：隧道监测　切入点：分布式光纤传感　出处：《南昌航空大学》2015年硕士论文

【摘要】：地铁隧道是大型基础设施中服役期限比较长的工程。鉴于地铁隧道渗漏、结构裂缝以及空间狭隘长、环境封闭的火灾威胁生命安全和造成经济损失,本课题进行分布式光纤传感技术在地铁隧道监测中的研究。本论文首先对分布式光纤传感技术发展进行了分析、比较和论述,重点论述布里渊光时域反射(BOTDR)技术;接着研究布里渊散射传感机理,建立布里渊散射与应变和温度传感模型,为BOTDR传感系统的研发奠定基础;然后分析了FFT算法和Mallat小波算法提取布里渊频移信号,比较两种算法提取应变布里渊频移信号灵敏度,从而提高测量精度;最后利用LabVIEW开发平台编程实现虚拟BOTDR传感系统监测地铁隧道VI程序,同时通过仿真测试结果进行分析得出该系统能很好的满足本课题的要求。本文的主要工作和研究成果如下:(1)设计并实现了基于LabVIEW的BOTDR传感系统监测地铁隧道VI程序。通过仿真虚拟应变和温度的监测与实际监测相比,误差分别大约为1.82%和8.33%。该结果表明搭建的虚拟监测系统比较理想,从而在没有硬件条件下,虚拟器件代替实体器件、虚拟处理,自定义模块和函数,通过修改参数设置来完成对布里渊散射分布式光纤传感技术的研究,从而大大降低了成本。(2)对本课题的BOTDR传感系统虚拟程序,采用了新的、稳定的“状态机和事件结构结合”的设计模式。该设计模式能够很好解决基本状态机的问题,从而提高了程序运行效率。该系统VI程序独特之处还有设计了数据采集存储模块,通过LabVIEW和数据库Access的连接,建立地铁隧道参数数据库,有利于储存地铁隧道参数重要信息,根据这些重要的参数信息加强隧道科学管理和提高隧道技术水平。(3)建立了基于FFT算法对BOTDR传感系统中的布里渊频移信号的频谱分析技术以及基于Mallat小波算法对布里渊频移信号特征提取。通过对比两种算法对布里渊频移信号的分析,Mallat小波算法能够更快速准确提取布里渊散射信号特征,从而为实际沿光纤检测信号的特征提取提供了重要参考意义,而且该算法对于其它分布式光纤传感技术有很好的参考价值,通用性很强。
[Abstract]:The subway tunnel is a project with a long service life in a large infrastructure. In view of the leakage of subway tunnel, structural cracks and narrow space, fire in closed environment threatens the safety of life and causes economic losses. In this paper, the development of distributed optical fiber sensing technology is analyzed, compared and discussed, with emphasis on Brillouin optical time domain reflectance (BOTDR) technology. Then the Brillouin scattering sensing mechanism is studied, and the Brillouin scattering and strain and temperature sensing models are established, which lays the foundation for the research and development of BOTDR sensing system, and then analyzes the FFT algorithm and Mallat wavelet algorithm to extract Brillouin frequency shift signals. The sensitivity of strain Brillouin frequency shift signal is obtained by comparing the two algorithms, and the measurement accuracy is improved. Finally, virtual BOTDR sensor system is programmed to monitor VI program of subway tunnel by using LabVIEW development platform. At the same time, through the analysis of the simulation test results, it is concluded that the system can meet the requirements of this subject very well. The main work and research results of this paper are as follows: 1) designed and realized the BOTDR sensor system based on LabVIEW to monitor the VI distance of subway tunnel. By simulating the virtual strain and temperature monitoring, compared with the actual monitoring, The error is about 1.82% and 8.33%, respectively. The results show that the virtual monitoring system is ideal, so that the virtual device can replace the physical device, the virtual processing, the custom module and the function without hardware. The research of Brillouin scattering distributed optical fiber sensing technology is completed by modifying the parameter setting, thus greatly reducing the cost. The stable design pattern of "combining state machine with event structure" can solve the problem of basic state machine well and improve the running efficiency of program. The VI program of the system is unique, and the module of data acquisition and storage is also designed. Through the connection of LabVIEW and database Access, the subway tunnel parameter database is established, which is helpful to store the important information of subway tunnel parameters. According to these important parameter information, we strengthen the scientific management of tunnel and improve the technical level of tunnel. We establish the spectrum analysis technology of Brillouin frequency shift signal in BOTDR sensor system based on FFT algorithm and the analysis of Brillouin frequency shift signal based on Mallat wavelet algorithm. By comparing the two algorithms to analyze Brillouin frequency shift signal, Mallat wavelet algorithm can extract Brillouin scattering signal features more quickly and accurately. It provides an important reference for the feature extraction of the detection signal along the optical fiber, and the algorithm has a good reference value for other distributed optical fiber sensing technology, and has a strong versatility.
【学位授予单位】：南昌航空大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U456.3;TN253

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