Numerical Models of Unstable Slopes in Seismic Areas—Based on 3D Geomodels

Abstract

This paper presents a series of new integrated 3D models of landslide sites that were investigated in very distinctive seismotectonic and climatic contexts in NW and SE Europe as well as in Central Asia (Tien Shan). First, we analyse ancient landslides with likely seismic origin marked by deep-seated failures, by a steep scarp and a massive failed body, by rock structures favouring static stability as well as by scarp initiation near the mountain top, far from river erosion processes. However, we present also one case study for a site near a major river, for which predictive slope stability models had to be developed: the right-bank slope located immediately downstream from the Rogun dam construction area. Multiple survey inputs and outputs were compiled in 3D geological-geophysical models and combined with high-resolution remote sensing data of the ground surface. Those models were used as inputs for 2D, 2.5D and 3D dynamic numerical simulations completed with the UDEC (Itasca) software. For some sites, a full back-analysis was carried out to assess the possibility of a seismic triggering of the landslide. For others, we simulated a series of possible future earthquake scenarios affecting the slopes. Simulations with discrete element codes also allowed us to model very large deformation and even dam formation. Interpretation of the complex inputs and outputs was enhanced by 3D stereo visualisation using a headset system allowing for full immersion in a virtual environment. We work now on the development of systems that allow several people to be immersed in the same virtual 3D model and to share their experience with each other.