ABSTRACT
The numerical samples are composed of a set of 5000 rigid disks with 8 large disks in a two-dimensional space. The radii of the particles are uniformly distributed by weight (or by volume fraction) between 0.5 m and 2 m. The radii of large particles are 10 m. They are introduced along a two column square grid. The initial sample is built by means of simple geometrical rules and then it is molded by means of a uniaxial compaction into a rectangular shape, before loading. The initial packing of particles is dense and disordered. The coefficient of friction between disks during compaction is set to zero in order to facilitate particle rearrangements. Once compacted, the sample is sheared biaxially under different confining pressures and for several friction coefficients between the disks (e.g.Taboada et al. in press).The vertical boundaries of the sample are defined as deformable walls. The confining pressure along deformable walls is applied by means horizontal external forces exerted on the disks located inside two vertical strips that are adjacent to these boundaries. Then, the sample is shortened along the vertical direction, up to 10% of its initial height.
