Abstract: Distributed optical fiber sensing system based on Brillouin scattering is capable of remote and highly accurate measurement. Accordingly, it has been used widely in the monitoring field of civil engineering. According to the relationship between Brillouin frequency shift and the optical fiber strain, and between Brillouin frequency shift and temperature, the frequency difference among various areas when the optical energy transfer reaches the maximum can be determined, thus the authors can get the temperature and strain information to achieve distributed measurement. As the distributed optical fiber measurement system based on BOTDA can simultaneously measure temperature and strain, it has greatly improved the efficiency of optical measurements. Temperature test shows that the accuracy of temperature measurement is restricted by the protective layer thickness of optical fiber. Therefore, it can be increased by improving the protective layer. As for the strain test, distributed optical fiber measurement system based on BOTDA proves to have excellent performance-price ratio as it makes the temperature compensation easy, and consequently simplifies the temperature compensation in the traditional strain gauge measuring method, and improves the accuracy of strain measurement.

Key words: distributed optical fiber ,    BOTDA ,    brillouin scattering  ,  strain measurement