Multiscale Modelling of the Slope Stability of Block-in-Matrix Materials Clairet I. Guerra 1 ; Jeisson J. Pinzón 2 ; Luis F. Prada 3 ; and Alfonso M. Ramos 4 1,2 Graduate Student, Dept. of Civil Engineering, Pontificia Universidad Javeriana. E-mail: C.guerra@javeriana.edu.co 3 Assistant Professor, Dept. of Civil Engineering, Pontificia Universidad Javeriana. E-mail: Lf.pradas@javeriana.edu.co 4 Associate Professor, Geophysical Institute, Pontificia Universidad Javeriana. E-mail: a- ramos@javeriana.edu.co Abstract: The soil tends to be evaluated as a homogeneous material and rocks as solid or continuous media. However, there has always been a great uncertainty when evaluating materials with a high degree of heterogeneity; such materials are referred as bimrocks. In this paper the implementation of multiscale numerical modeling is shown for the study of materials with discontinuous nature. Triaxial tests using DEM were developed, where the resistance variation parameter, according to the block volumetric proportion (BVP) and the blocks shape was shown. Slopes in FEM were modeled with the inclusion of individual blocks and compared with limit equilibrium slope analysis using parameters from homogenized resistance. It was established that it is possible to define the parameters of homogenized resistance as dependent exponential functions of the surface area ratio of the blocks. It was showed a decreasing friction angle trend as the sphericity of the blocks decreased, in addition to conventional friction angle increase and decrease in cohesion with increasing volume ratio of blocks. A comparison of the factor of safety obtained by finite elements and limit equilibrium is performed. Finally, the need of a multiscale approach for heterogeneous materials analysis is established. INTRODUCTION The term Bimrock/Bimsoil (BIM=blocks in matrix) represents a type of soil composed of clasts or blocks embedded in a matrix of fine material (Lindquist and Goodman, 1994; Medley, 1997; Medley, 1994) These materials comprise, among others, mélanges, cataclastic rocks, weathered and highly tectonized rocks (Graziani et al. 2012; Irfan and Tang, 1993; Medley and Goodman, 1994). Many geotechnical professionals are unaware of recent developments and new concepts developed for these materials and their significance in engineering, and do not consider the heterogeneous nature of soils in their designs (Wakabayashi and Medley, 2004). This lack of knowledge leads to frequent simplified characterization of the material, regardless of the presence of blocks in the soil mass and also ignores the high uncertainty associated to geotechnical characterization of Bimrocks (Hussein et al. 2000; Medley, 1997; Sonmez et al. 2004). Materials like mélanges, colluvium deposits, weathered soils among others, make up the group of Bimrocks (Coli et al. 2012; Graziani et al. 2012; Medley and Goodman, 1994), materials that pose problems for geotechnical engineers when attempting to characterize those mixtures. Therefore it is important to have at least a common conceptual understanding of what the Bimrocks are, in order to be recognized by professionals, taking into account the processes of origin, structure and weathering in a proper way. This investigation based on numerical modelling, has been developed in order to present tools to understand the strength characterization of Geo-Chicago 2016 GSP 271 658 © ASCE