Using TDR Cables and GPS for Landslide Monitoring in High Mountain Area

Time domain reflectometry (TDR) is performed as a complement to the monitoring methods in subsurface deformation in slope together with the global positioning system (GPS) to monitor ground deformation of high-altitude landslides in Li-shan. Four TDR cables were installed in drill holes near the monitoring stations in the landslide area. According to the recorded TDR waveforms, there were shear and tensile zones under the B-5, B-9, C-1, and C-2 stations. A comparison of the TDR waveforms with the monitored data and boring log revealed that the subsurface sliding occurred between layers of colluvium and strongly weathered slate. Three GPS receivers were installed to measure ground displacement in the landslide area. The results from the GPS were compared with the surface extensometers data on-site. The two initial baseline lengths were 451,188.10 and 908,212.4 mm, respectively. The optimal data reduction achieved used a 3 h session with moving average for each hour's GPS data. The standard deviation values of the GPS were 2.16 and 2.44 mm, respectively, on-site. The results of TDR and GPS measurements showed their applicability in the deformation monitoring of high-mountain landslides.