3D Slope Stability Analyses of a Complex Formation with a Block-in-Matrix Fabric

Heterogeneous rock bodies composed of strong rock blocks surrounded by a weaker finer-grained matrix are often referred to as “BIMrocks” (Block-In-Matrix rocks). These complex formations present a high spatial, dimensional and lithological variability, which makes their characterization an extremely challenging task. As a consequence, geopracticioners have often planned engineering works in bimrocks ignoring the presence of the stronger rock inclusions. However, it is essential that blocks be considered in the analyses in order to obtain reliable results. In fact, rock inclusions strongly affects the strength, deformability and failure surfaces of these geomaterials. In this paper 3D stability analyses are performed with the FLAC 3D code on slope models with variable Volumetric Block Proportions (VBP) to investigate the influence of the rock inclusions on their stability. In order to take the inherent variability of bimrocks into account, a Matlab code was implemented to generate spherical blocks of variable dimensions and locate them randomly within the slope models. Moreover, the stability of a matrix-only slope model is also analyzed by way of comparison. Finally, the paper compares and comments on the results of 2D numerical simulations previously carried out by the author for the same complex block-in-matrix formation.