Analysis of the role of discontinuities on landslide instability at various scales utilising remote sensing data and numerical modelling

Abstract

This research focuses on the influence of discontinuities on the origin and development of landslide instability mechanisms at different scales. Various remote sensing techniques have been used for data acquisition to characterize discontinuity and landslide-related features. The remotely captured data was subsequently interrogated using a variety of analytical methods and numerical modelling to investigate the role of discontinuities at different scales in the origin and development of rock slides through analysis of selected case studies. The investigation has been carried out through landslide susceptibility mapping (LSM) with the inclusion of discontinuities, the use and application of 3D distinct element method (DEM) modelling of the Hell’s Mouth landslide in the UK, 2D DEM modelling of a catastrophic rock avalanche in Italy, and the analysis of slope instability in an open pit mine (more than 200m height) in South America using both a 2D finite/discrete element method (FDEM) approach and a 3D DEM approach. The result of LSM demonstrates that integration of discontinuity orientation through GIS based kinematic analysis can effectively improve landslide prediction using machine learning (ML) modelling. In Hell’s Mouth case study, numerical modelling and field observations both suggest that the cliff instability was characterised by a combination of planar sliding, wedge sliding, and toppling modes of failure controlled by the discrete fracture network geometry. For the Italian pale landslide, it was controlled by translational sliding along a folded bedding plane, with toe removal induced by river erosion resulting in daylighting of the bedding, creating kinematic freedom for the landslide. In addition, due to the presence of an anticline, the landslide region was constrained in the middle-lower section of the slope where the relatively high inclination of the bedding plane was detected. With respect to the inter-ramp deformation in South America, modelling results indicate the potential control and influence of a rock bridge, constrained by two faults at the toe of the slope. It was also demonstrated that blasting-induced weak zones and sequential excavations were potential key triggers of the observed slope deformation.