BOTDR光纤温度监测技术在土木工程中的应用研究

布里渊光时域反射计(BOTDR)是一种新型的分布式光纤传感技术。布里渊光频移量不仅与光纤的应变状态相关,还与光纤的温度存在相应的线性关系,因此BOTDR可以用作分布式的温度监测。本文对基于BOTDR的分布式温度监测技术及其在土木工程中的应用展开了实验研究,研究选用的是美国康宁公司900μm单模紧套光纤,实验标定布里渊光频移量对温度的敏感度为1.43 MHz/℃。通过室内外实验以及在实际隧道工程中的应用,验证了BOTDR的温度测量精度达2℃,因此将该技术应用于分布式温度监测是可行的,长期稳定性良好。

BOTDR Optic Fiber Temperature Monitoring Technique and Its Application in Civil Engineering

Brillouin Optical Time Domain Reflectometer (BOTDR) is a newly develoed distributed opticalfiber sensing technology based on Brillouin back scattering. With the advantages of wide applicability,long distance, distributed measurement, high sensitivity and long-term service life, BOTDR has been ap-plied to structure health monitoring. When a probe light is launched into a sensing optical fiber, the Bril-louin spectrum of every point along its length can be obtained. The frequency shift of Brillouin back-scat-tered light varies in proportion to the optical fiber's temperature as well as to the strain applied to it, andthus BOTDR can be used for temperature monitoring. In this paper, the temperature characteristic ofBOTDR were investigated and the application of BOTDR based distributed temperature monitoring tech-nology in civil engineering was studied. 900μm single mode tight-buffered optical fiber of Corning Co.,whose coefficient of Brillouin frequency shift to temperature was calibrated as 1.43Mhz/℃, was selectedfor experiments and projects. It was verified that BOTDR could achieve a measurement accuracy of 2℃ bythe lab tests and a case in a tunnel. The distributed temperature monitoring method using BOTDR wasproved to be applicable and stable.