Résumé
In the realm of granular materials, cohesive interactions among particles play a pivotal role ininfluencing the macroscopic behavior of the material. The importance of cohesive granular mediaextends to a variety of fields, underpinning crucial aspects of particle processing, soil mechanics andpowder technology. In the specific case of railway ballast, the presence of fine particles (resultingfrom the gradual degradation of the grains), combined with external agents (infiltration of water, silt,clay, climate variation), contribute to accelerate the deterioration of the ballasted track. These finematerials then act as a binder, causing the larger particles to stick together, drastically altering thestability characteristics of the ballasted track [1]. Wet or more generally cohesive granular materialshave been extensively studied in the literature, using model experiments, numerical experiments, andtheoretical approaches [2, 3] In general terms, local cohesive forces f0 , whatever their origin, impartan extra cohesive strength c (also called “Coulomb cohesion“) to granular materials in addition tothe inherent frictional strength sin(φ), where φ is assumed to be the so-called macroscopic frictionangle in dry condition. However, in the large majority of existing work dealing with cohesive or wetgranular media, circular (in 2D) or spherical (in 3D) particles have been used. Real grains can haveirregular/elongated/non-convex shapes with potentially more than one point of contact, thus increas-ing their net particle-particle cohesive/friction force which, in turn, will increase the cohesive/frictionstrength of the system by impeding particle rotations. Considering a realistic shape is even more cru-cial in a railway context to improve track design, maintenance practices, and overall railway systemperformance. How the cohesive strength, and the underlying microstructure, evolves depending ongrain shape remains largely unexplored. . We present a systematic numerical investigation concerningthe effects of particle shape (i.e., angularity) parameters on the quasi-static shear strength of cohe-sive granular packings under bi-axial conditions for various confining stress P . We consider irregularpolygons with an increasing number of sides, ranging from triangles to disks. The packings behaviordepends on the dimensionless number η = f0/P d, also known as the cohesion index, being d theaverage grain diameter. η is varied between 0 (dry) to 0.6 (strongly cohesive) by varying P . We findthat the macroscopic friction angle increases with grain angularity and saturates at larger angular-ity, as in dry case. In contrast, the cohesive strength is an increasing function of grain angularity. Inother word, our numerical results evidence the amplifying effect of particles shape angularity on thecohesive strength in cohesive granular media