Applying time domain reflectometry to quantification of slope deformation by shear failure in a landslide

This study employed time domain reflectometry (TDR) to monitor the deformation of grouted coaxial cables in a landslide over an extended period. Laboratory experiments were performed to quantify the magnitude of the deformation by shear failure to simulate types of cable deformation in the field when two localized shear types had been detected using TDR. The study applied two qualification methods to measure the magnitude of the laboratory shear deformation. The integration method of the TDR reflection coefficients demonstrated a stronger significant positive correlation with the shear displacement than did the linear regression method of reflection coefficients in relation to the deformation magnitude of the cables. The integration method indicated increases of localized shear displacements from 15 to 47mm over time at 10.33- and 13.36-m depths in the landslide. The average maximum magnitude of the cable deformation by shearing was 47mm corresponding to a 210-m reflection coefficient when the cable ruptured in the case study. Overall, the location and magnitude of shear deformation in the landslide can be determined using changes in the TDR waveforms and calculations of the integration method of reflection coefficients.