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This presentation demonstrates the role and use of numerical analysis by discontinuum and continuum modelling for the understanding of rock slope behavior. The objective is to find well-proven engineering solutions to slope stability problems. Following a short overview of the numerical methods available, FEM, DEM and FEDEM, the presentation considers two case studies.

The First Case Study describes the rock mechanics and rock engineering activities carried out in order to assess the stability of a 120 m high rock slope in a limestone quarry. The rock slope is characterized by the presence of a large size rock volume, in limit equilibrium conditions, which impairs quarrying activities. In situ investigations including detailed geological mapping and 3D imaging with a laser scanning equipment are described. The results of real-time monitoring by ground based interferometric synthetic aperture radar (GBInSAR) images are also presented. Three-dimensional discontinuum modeling involving a back analysis of a plane sliding instability at the toe of the slope and detailed slope stability studies of the rock volume, aimed at the definition of the likely instability scenarios, are described.

The Second Case Study considers the interaction between twin tunnels and a deep-seated landslide. The geological, hydrogeological, and geotechnical conditions, the available monitoring data on the landslide movements, based on interferometric synthetic aperture radar (InSAR) images, real-time monitoring through multi-purpose electronic surveying instruments and inclinometers are described. Three-dimensional continuum modelling is discussed with the purpose to back-analyze the monitored surface and subsurface deformations, in order to gain insights into the interaction, during excavation, between the twin tunnels and a deep- seated landslide. The modelling results obtained in terms of induced displacements on the ground surface and below, the induced plastic zones, and the shearing strains along the shear surface, are compared with the performance monitoring data.

In conclusion, an attempt is made to assess the potentials and limitations of computer modelling of complex conditions as a means for forecasting the slope behaviour, based on the real-time monitoring data obtained at a given site.