Verification of a distributed fiber optic sensing slope stability monitoring solution

This paper describes the testing of a novel ground condition and slope stability monitoring system based on Distributed Rayleigh Sensing (DRS) on a landslide observatory operated by the British Geological Survey (BGS). The DRS system uses the backscattered light from buried fiber optic cables to determine the strain and temperature at any point along the fiber up to distances of over 50 km and has been shown to respond to ground movement, moisture content changes and temperature variations. The output of the fiber is compared to that expected based on the known geology of the slope and other instruments such as tiltmeters and moisture content sensors. In addition to long-term strain and temperature measurements, the system can also sense acoustic vibrations and can be used to make active and passive seismic surveys to give a comprehensive 3d picture of the subsurface state. The results show that the DRS system can provide improved spatial and time resolution and sensitivity to give a more comprehensive and detailed picture of slope behavior than would otherwise be possible. Such detail allows improved landslide prediction methods and early warning systems to be developed.