FBG-based health monitoring for the secondary lining of Bainijing tunnel No.3 in Kunming,China

摘要

The fiber bragg grating (FBG) sensor is a newly developed monitoring technique. Health monitoring using FBG sensing technology has been carried out at the Bainijing tunnel No.3 located in Kunming,China. The principle and advantages of FBG sensingr technology are briefly introduced, and the installation scheme of FBG sensors is put forward according to the results of numerical simulation for the secondary lining of the tunnel. In order to solve the problem that the Bragg wavelength shift is simultaneously sensitive to strain and temperature, a temperature compensation method is presented. According to eleven months strain the results of strain monitoring during monitoring results, the key factor resulting in increase of strain in the secondary lining of the tunnel is deternined. Finally, the characteristics of strain and rainfall variations with time are analyzed,and the health diagnose of the tunnel is given. The results show that the FBG sensing technology can reveal the distribution of strain and diagnose health status of tunnels.