Application of ultra-weak FBG technology in real-time monitoring of landslide shear displacement.

Real-time monitoring of landslide shear displacements is important for early warning of landslide hazards. However, distributed and real-time monitoring of landslide displacements cannot be fully realized by using existing monitoring methods. In this work, a new strain-sensing optical cable based on ultra-weak Fiber Bragg Grating (UWFBG) technology was designed. Two computational models to convert measured cable strains to shear displacements were proposed. Furthermore, experiments were conducted to verify the models. The advantage of the UWFBG cable is its ease of installation. In particular, it can be installed in abandoned inclinometer casings to extend the lifespan of existing inclinometer boreholes. The UWFBG cable and the proposed deployment method were applied to the Majiagou landslide in the Three Gorges Reservoir (TGR) area in China. Distributed deformation data were collected and transmitted to a remote computer terminal in real time (6-min interval). The monitoring results show that two shear deformation zones of the landslide were successfully identified by the UWFBG cable. The proposed method based on the UWFBG technology provides a new means to achieve distributed, real-time monitoring of landslide shear displacements. [ABSTRACT FROM AUTHOR]