Monitoring The Stability Of Loess Landslide Using Terrestrial Laser Scanning Techniques

The characteristics of fragile geological conditions and human activities can induce serious landslide disasters, which occur frequently in the loess areas and cause a devastating loss. Therefore, monitoring the stability of loess landslides become the most important prevention work. Terrestrial laser scanning(TLS) is one of the most promising surveying techniques for landslide characterization and monitoring. The deformation information can be obtained completely by a series of proceeding of TLS data that base on sequential scans.In this study, a validation simulation experiment and a indoor experiment were performed to study the acquisition of the TLS data, the processing of the point cloud, 3D model reconstruction and the measurement methods of landslide displacement. Riegl VZ-1000 terrestrial laser scanner realized on a loess landslide body located on the miaodian village at South Jingyang in Shaanxi Province, China, which in order to test the laser scanning capabilities and evaluate the slope stability.(1) The paper firstly discussed the terrestrial laser scanning technology error and the error propagation rules in detail, and then proposed a set of control method during the acquisition of TLS data.(2) The paper used Matlab for processing point cloud downsample, denoise, registration,etc. For the registration of landslide model data, an improved Iterative Closest Point(ICP)algorithm was be used, which based on K-D tree to reduce searching time of corresponding points.(3) The barycenter method and the fitting method were used to detect deformation in only a few selected positions, while the cloud to cloud comparison method provide the whole deformation of the slope surface. The method of directly comparing Digital Elevation Models(DEM) from different TLS campaigns provided a 1D deformation measurement, in the z direction. The function “shortest distance” available in Geomagic Qualify software was particularly useful when the direction of movement is unknown. In experiment, spherical marking internal accord accuracy was 0.25 mm. It verified whether the accuracy of the Scan Scanstation2 scanner can be enough to enable monitoring or not. The determinate of displacement of point cloud and rotate angle was completed by fitted line.(4) In the indoor test, it calculated the change size of volume of slope surface by Cyclone or Geomagic, and found that the relative deviation of them was 3%. The result indicated that the three-dimensional model of the two methods are approximately.(5) Finally, it obtained the 3D model and feature information from the point cloud data of the miaodian village loess landslides. And used the Fellenius method to analysis the slope stability under different conditions. The results show that the factor of water will lead the slope in an unstable state.