Coupled distinct element method computational fluid dynamics analyses for reservoir landslide modelling

The Vajont landslide involved a large mass of rock splashing at high speed into the reservoir which in turn generated a high impulse water that overtopped the dam and swept away the downstream village. In several cases of reservoir landslide, albeit the flood defence structures may remain intact, a catastrophe still occur due to the generation of a 'tsunami' wave. Since the features of the tsunami wave strongly depend on the physics of the rock splashing and the subsequent rock-water interaction, a numerical tool accounting for such physics is required for predictions to be reliable. Here, the formulation of a coupled 3D Distinct Element Method (DEM)-Computational Fluid Dynamics (CFD) code used to simulate the rock slide from onset to impact with the reservoir and the subsequent generation of the impulse wave, is presented. To run realistic simulations in an affordable runtime, coarse graining is employed. The main results of quasi 3D analyses in plane strain along two cross-sections representative of the eastern and western slope sectors are presented. The results show to be in broad agreement with the available recorded observations.