Influence of small particle surface asperities on macro and micro mechanical behavior of granular material

Abstract

The shape of particles can have a great impact on the mechanical behavior of granular material, which is not only limited to general shape measures such as sphericity and roundness, but also applies for small scale measures such as surface asperities. In this study, triaxial tests on 3D printed particles and DEM tests show that small surface asperities on spherical particles can contribute significantly to the peak strength and dilatancy of granular material, which cannot be reflected by simply altering the traditional contact parameters in DEM. Using polydispersed particles with artificially designed surface asperities in the form of bumps for laboratory and DEM triaxial tests, both macro and micro scale behavior of granular material are analyzed to reveal the influence of these small surface asperities. The result shows that surface asperities can change the coordination number, anisotropy, and normal contact force on the micro scale, increasing the interlocking between particles and restricting particle rotation, which leads to the increase of peak strength and dilatancy on the macro scale. Although the commonly adopted approach of introducing rolling resistance to reflect shape influence can help to enhance the simulation of stress‐strain relationship, especially for particles with relatively small artificial asperities, the micro scale influence of rolling resistance and surface asperities are found to be different as the size of the asperities increase.

Spatial Structure Characteristics of Underground Reservoir Water Storage Space in Coal Mines Considering Shape Characteristics of Crushed Rock

“…The first scale indicators describe the overall shape characteristics of particles, including the long-to-medium axis ratio e, the medium-to-short axis ratio f and the sphericity ψ; the second scale indicator describes the angular characteristics of particles, which is usually expressed by the convexity C v ; and the third scale indicator describes the surface texture of particles, which is characterized by the roughness. Relevant research results indicate that the third scale shape indicator does not significantly affect the packing structure and mechanical properties of particle systems [27][28][29][30], as typically characterized by the friction coefficient in discrete element numerical simulations [31]. Therefore, this study focuses solely on the first and second scale shape indicators of crushed rock.…”

Effects of particle breakage on the mechanical characteristics of geogrid-reinforced granular soils under triaxial shear: A DEM investigation

“…In DEM, there are contact forces between soil particles, which have significant influences on the macro-mechanical response of granular soils. Based on the value of contact force, the contact force can be classified as: strong contact force and weak contact force [62][63][64]. Strong contact force is considered to bear larger loadings than that of weak contact force.…”

Generation of 3D geotechnical particles using random angular bend algorithm

“…When the simulation of geo‐materials is performed utilizing discrete element method (DEM), their mechanical behaviors are closely related with the micro‐structures of generated rock/soil mass 2,3 . To accurately reflect the mechanical behaviors of geo‐materials, the simulation of micro‐structure of rock‐soil mass plays an important role in the subsequent modeling, in which the selection of generating method (including overlapping check method and throwing method of particles) of particle shape is more significant for reflecting the micro‐structure 4,5 . Reproducing the micro‐structure of geo‐materials and establishing the relationship between micro‐structure and macro‐behaviors are efficient measures to explore the mechanical behaviors of geo‐materials and are also pivotal for revealing failure mechanism and patterns in multi‐scales and improving design and construction quality 6,7 …”

“…2,3 To accurately reflect the mechanical behaviors of geo-materials, the simulation of micro-structure of rock-soil mass plays an important role in the subsequent modeling, in which the selection of generating method (including overlapping check method and throwing method of particles) of Method proposed in the paper Concave / convex polyhedron Yes particle shape is more significant for reflecting the micro-structure. 4,5 Reproducing the micro-structure of geo-materials and establishing the relationship between micro-structure and macro-behaviors are efficient measures to explore the mechanical behaviors of geo-materials and are also pivotal for revealing failure mechanism and patterns in multi-scales and improving design and construction quality. 6,7 To accurately generate the particles with arbitrary shape, plenty of researches have been conducted about the generation of 2D or 3D random particles.…”