Discrete element modelling of a soil-rock mixture used in an embankment dam

• A 3D random meso-structure modelling system of (S-RM) is developed.
• Based on the Voronoi cell, a method representing volume strain at particle scale is proposed.
• There is close contact between macro mechanical behavior and deformation localization of (S-RM).
• Rock blocks influence meso and macro mechanical behaviors of the (S-RM).

The deformation and failure mechanism and the mechanical behavior of soil and soil-rock mixture used in an embankment dam was studied using numerical testing, based on a discrete element method (DEM). In this work, a 3D random meso-structure modelling system of soil-rock mixture is developed and used to generate a meso-structural model of soil-rock mixture. A non-overlapping combination method was used to model convex polyhedron rock blocks for the DEM numerical simulation. Based on the Voronoi cell, a method representing volume strain at particle scale is proposed. Results show that there is close contact between macro mechanical behavior and deformation localization of the sample. Rotation, occlusion, dilatation and a self-organizing force chains are remarkable phenomena of the localization band, and occur simultaneously with localization. Rock blocks influence localization characteristics and distribution of the force chains of the soil-rock mixture sample. Rotation and overcoming of the occlusion of the larger rock blocks in the localization band are more difficult than for small soil particles, which is the important reason for higher shear strength of soil-rock mixture than that of soil. The shearing process leads to anisotropy of the contact force, reaching its maximum at the start point of the plastic deformation, and then begins to decrease in the subsequent process.

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