A FEM-DEM numerical analysis to study the instability of the Passo della Morte slopes (Carnian Alps, Italy)

The natural formation of rock slopes can result in the initiation of complex failure processes, including the deformation and fracturing of intact rock and the displacement of large individual blocks. The presence of non-persistent discontinuities may also promote stress concentrations that would result in stress induced fractures leading to the formation of continuous failure surfaces, thus creating the condition of kinematic freedom for previously finite and tapered blocks that may result in slope failure. This type of mechanism cannot be analyzed using a limit equilibrium approach and requires models capable of considering rock mass plastic yield, simulation of shear/tensile fracturing and ability to consider kinematic processes. In this context, hybrid finite-discrete element methods (FDEM) provide an attractive option for modelling rock slope failure mechanisms. In this paper a FDEM approach was applied to study a rock face located near the Passo della Morte (Carnian Alps, Italy), on the left flank of Tagliamento River valley. The rock face is approximately 130 m wide and 250 m high (650 to 900 m a.s.l.). The study includes 2D numerical analysis of a critical section for which the potential failure mechanism would be controlled by a series of faults bounding a densely stratified rock mass crossed by very persistent sub-vertical joints. Overall, the rock mass is divided into a large number of blocks of variable size, that are isolated by a dense network of discontinuities and random fractures. The importance of damage in the rock slope mass has been recognized by several researchers using remote sensing methods.