Application of Distributed Fiber Optic Sensing Technique to Monitor Stability of a Geogrid-Reinforced Model Slope

The development of the smart geosynthetics in recent years has shown tremendous potential with regard to its capability to strengthen geotechnical structures and, meanwhile, evaluate the local strains/stresses. This paper introduced the application of a distributed monitoring system to monitor a laboratory model slope reinforced with smart geogrids, in which the coherent optical frequency domain reflectometry technology (C-OFDR) was used to continuously monitor the geogrid deformations under different surcharge loadings. It showed that the measured results using C-OFDR technology were generally consistent to those from the fiber Bragg grating (FBG) sensors; however, C-OFDR has other significant advantages over the FBG technology. Empirical relationships between the geogrid characteristic strain measured by the C-OFDR sensors and the factor of safety calculated by the conventional limit equilibrium method were established, making it possible to use the geogrid characteristic strain to monitor the slope stability. This study proved the effectiveness of the distributed C-OFDR sensing technology in monitoring the geogrid-reinforced slope stability in the laboratory scale, a critical stepping stone to extend this technology to the field.