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.