基于BOTDR的分布式光纤应变检测系统

发布时间：2018-03-04 06:41

本文选题：应变检测　切入点：BOTDR　出处：《太原理工大学》2017年硕士论文　论文类型：学位论文

【摘要】：随着我国基础建设规模的扩大,隧道、桥梁、大坝等基础设施数量不断增大,其长期运行带来的安全隐患问题也不断增加;同时由于环境破坏严重,诸如山体滑坡、地表塌陷等地质灾害也时常发生。因此如何对大规模基础设施和特殊地貌区进行结构健康监测和灾害预警具有重要意义。结构健康监测多数基于应变检测实现,传统的应变检测技术主要依靠应变片或者振弦式应变传感器来实现点式测量,这两者易受环境腐蚀,不宜长期检测,同时在大规模测点容量的应用场合中,点式传感器布设冗杂、信号传输不便、抗电磁干扰差,给工程应用带来困难。相比于传统应变传感器,分布式光纤应变传感器具有抗电磁干扰、集传输与传感为一体、耐高温、灵敏度高、体积小等优点,特别适合在易燃、易爆、受限空间及强电磁干扰等恶劣环境下使用。而基于BOTDR的分布式光纤传感技术除以上优点外,还有带宽大、损耗低,传感距离长等特点,可以很好完成健康检测和预警任务。首先通过布里渊散射特性分析基于BOTDR的应变传感机理,得出布里渊频移与应变的线性关系,并理论分析相干检测的机制,以结合微波扫频技术给出应变传感系统的总体设计方案。随后分析布里渊散射谱的特征,以此阐述洛仑兹曲线拟合算法(L-M算法)的流程和意义,并根据检测方式和数据采集装置的特点设计出基于LabVIEW的应变解调软件。其次,为便于样机集成,根据实验室现有的AD9467模数转换芯片和Kintex-7系列XC7K325T开发板卡,基于Verilog语言设计出了AD采集和PCIe DMA高速数据传输软件模块,并完成每个程序功能的初步验证,为后期设计完整的高速采集卡奠定了基础。最后根据总体设计方案,搭建出实验传感系统,进行拉伸实验,在10.19km的传感光纤末端处3.9m长度上施加0με-8000με的应变,解调的频移误差为±1.05MHz,对应应变测量误差为±24.35με,因此本分布式光纤应变检测系统可为工程设施、特殊地貌区的结构健康监测提供一种可行的检测方案。
[Abstract]:With the expansion of our country's infrastructure, the number of tunnels, bridges, dams and other infrastructure facilities is increasing, and the hidden safety problems brought by its long-term operation are also increasing. At the same time, due to the serious environmental damage, such as landslides, Geological disasters such as surface collapse also occur frequently. Therefore, it is of great significance to monitor structural health and early warning of disasters in large-scale infrastructure and special geomorphological areas. Structural health monitoring is mostly based on strain detection. The traditional strain detection technology mainly relies on strain gauges or vibrating string strain sensors to realize point measurement. Both of them are vulnerable to environmental corrosion and are not suitable for long-term detection. At the same time, in the application of large scale measuring point capacity, The point sensor is jumbled, the signal transmission is inconvenient, and the electromagnetic interference is poor. Compared with the traditional strain sensor, the distributed fiber optic strain sensor has anti-electromagnetic interference, which integrates the transmission and sensing, and can withstand high temperature. High sensitivity, small size and so on, especially suitable for use in flammable, explosive, confined space and strong electromagnetic interference, etc. In addition to the above advantages, the distributed optical fiber sensing technology based on BOTDR also has large bandwidth and low loss. Because of the long sensing distance, the task of health detection and early warning can be accomplished well. Firstly, the strain sensing mechanism based on BOTDR is analyzed by Brillouin scattering characteristics, and the linear relationship between Brillouin frequency shift and strain is obtained. The mechanism of coherent detection is analyzed theoretically in order to give the overall design scheme of strain sensing system combined with microwave frequency scanning technology. Then, the characteristics of Brillouin scattering spectrum are analyzed, and the flow and significance of Lorentz curve fitting algorithm (L-M algorithm) are expounded. The strain demodulation software based on LabVIEW is designed according to the detection method and the characteristics of data acquisition device. Secondly, in order to facilitate the prototype integration, the board card is developed according to the existing AD9467 A / D conversion chip and Kintex-7 series XC7K325T in the laboratory. The software module of AD acquisition and PCIe DMA high-speed data transmission is designed based on Verilog language, and the initial verification of each program function is completed, which lays the foundation for the later design of complete high-speed data acquisition card. Finally, according to the overall design scheme, The strain of 0 渭蔚 -8000 渭蔚 was applied on the 3.9m length at the end of 10.19km sensing fiber. The frequency shift error of demodulation is 卤1.05 MHz and the corresponding strain measurement error is 卤24.35 渭蔚. Therefore, this distributed optical fiber strain detection system can provide a feasible detection scheme for structural health monitoring in engineering facilities and special geomorphological areas.
【学位授予单位】：太原理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TP212;TP274

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