Monitoring of landslides and debris flows using FBG sensing technology

Landslide is a typical geological hazard occurring in mountainous regions. Debris flows will be induced by heavy rainfall. But it is too difficult to predict debris flow and landside by traditional numerical methods. Thus instrumentation and warning methods are of great importance. Traditional technologies which based on electric sensing technique have certain limitations. The optical fiber sensors introduced in this paper can overcome those limitations. This paper presents two new optical fiber sensor systems: one is the fiber Bragg grating (FBG) based in-place inclinometer for monitoring landslide movements and the other is the FBG based column-net system for monitoring debris flows. This paper presents the calibration results of FBG based in-place inclinometers in laboratory. It is found that the calibration results are in good agreement with theoretical results. Both the FBG based in-place inclinometers and the FBG based column-net system have been installed at a site in Weijiaogao, Beichuan, Sichuan Province of China. Preliminary monitoring results are reported in the paper.