Direct shear behavior of gravel-rubber mixtures: Discrete element modeling and microscopic investigations

In this paper, a newly developed 3-dimentional discrete element model (DEM) for gravel-rubber mixtures (GRMs), namely DEM4GRM, that is capable of accurately describing the macro-scale shear response (from small to large deformation) GRMs in direct box apparatus presented. Rigid gravel grains are modelled as simple multi-shape clumps, while soft rubber particles modeled by using deformable 35-ball body-centered-cubic clusters. Mixtures prepared with different volumetric content ( VRC ) at 0, 10, 25, 40 and 100%, statically compressed under 30, 60 100 kPa vertical stress then sheared, closely simulating reference laboratory test procedure. The variation micro-scale factors such fabric, normal tangential force anisotropy carefully examined throughout shearing process described means novel micro-mechanical relationships valid GRMs. Moreover, strong-force chains scrutinized identify transition from rigid granular skeleton gain insights on load transfer deformation mechanisms It shown development fabric during related strength GRMs, strongly depends . Besides, appear be primarily formed gravel-gravel contacts (resulting rigid-like mechanical behavior) up = 30% , rubber-rubber (causing soft-like response) beyond 60%. Alternatively, < 60%, predominant network an intermediate behavior observed. This consistent behavioral trends observed macro- responses.