Slope Stability Analyses Subjected to Slide Head Toppling Failure Mechanisms

It is faulty to analyze the jointed rock slopes’ stability susceptible to a combination of modes of failure composed of sliding around the toe region and toppling of the rock blocks on the upper part of the slope based on the current analytical methods, which are based on assumption that the distribution of the potential failure surface bounding the potential mixed failure runs predictably from crest to toe of the slope. An Analytical model that takes into consideration the kinematic mechanism of the discontinuous rock slope with counter-tilted weak plane subjected to a combination of failure mechanisms involving sliding and toppling has hence been presented in this chapter. This involves an iterative process which involves the calculations of the dimensions of all the individual blocks as well as the forces acting on them, and then stability of every block is examined, starting at the uppermost block. The stability analysis of each block is determined. The blocks may either be stable, topple or slide. The proposed analytical methods could curtail errors incurred due to the acceptance of the single weak plane for quantifying the failure mechanisms composed of slide head toppling rock slopes in physical situations with two planar weak planes

An Improved R-Index Model for Terrain Visibility Analysis for Landslide Monitoring with InSAR

The interferometric synthetic aperture radar (InSAR) technique is widely adopted for detecting and monitoring landslides, but its effectiveness is often degraded in mountainous terrains, due to geometric distortions in the synthetic aperture radar (SAR) image input. To evaluate the terrain effect on the applicability of InSAR in landslide monitoring, a variety of visibility evaluation models have been developed, among which the R-index models are quite popular. In consideration of the poor performance of the existing R-index models in the passive layover region, this study presents an improved R-index model, in which a coefficient for improving the visibility evaluation in the far passive layover regions is incorporated. To demonstrate the applicability of the improved R-index model, the terrain visibility of SAR images in Fengjie, a county in the Three Gorges Reservoirs region, China, is studied. The effectiveness of the improved R-index model is demonstrated through comparing the visibility evaluation results with those obtained from the existing R-index models and P-NG method. Further, the effects of the line-of-sight (LOS) parameters of SAR images and the resolution of the digital elevation model (DEM) on the terrain visibility are discussed