Characterization of sliding surface deformation and stability evaluation of landslides with fiber-optic strain sensing nerves

Deformation monitoring of sliding zones or surfaces is of great significance to investigate evolution stages and triggering factors of landslides. The fiber-optic strain sensing cables, similar to human nerves, are capable of capturing slight movements in a distributed sensing and nearly real-time manner. However, the interaction between fiber-optic strain sensing nerves and surrounding geomaterials under shearing remains unclear. In this study, a novel analytical methodology for interpreting the cable-soil interaction under shear deformation and a reliable solution to calculate the shear displacements of critical interfaces in landslides are presented. The feasibility of the proposed method is proven through laboratory shear tests and later applied to calculate the shear displacements of the Majiagou landslide located in the Three Gorges Reservoir region, China. Finally, the empirical relationships between the measured strains and factors of safety are established. It is proved that the reservoir water level drawdown and rainfall cause accelerated shear deformation of this landslide.