A coupled scaled boundary-discrete-finite element method for particle breakage modelling in granular media
2016
The physical behavior of granular media e.g rock-fills and cohesion-less soils are governed, in part, by
two mechanisms viz. grain-to-grain interaction; and the particle breakage of the individual grains. Grain
interaction is predominantly described by the contact condition of the grains, whereas particle breakage
depends on the stress state within each grain. Both the grain interaction and its corresponding stress state
have to be appropriately accounted for when modelling the behavior of granular media. To achieve these
objectives, this study develops a novel computational framework that combines the use of the scaled
boundary finite element method (SBFEM) and the discrete element method (DEM). This approach
employs a two-step solution process to resolve the dynamics of the grain interaction and to determine
the stress state in individual grains. In the first step, the dynamic interaction between the grains are
resolved using the DEM. Once the forces resulting from the interaction between the grains have been
determined, a stress analysis is carried out using the SBFEM to determine their corresponding stress
states. The stress state in a grain determines the condition for particle breakage according to a
predetermined failure criterion. In this way, this method the best use of the salient features of both the
DEM and SBFEM.
Each grain is a particle within the framework of the DEM. Arbitrary sided polygonal particles are
employed to model the morphology of each grain. The contact interaction between the particles is
resolved using a potential-based contact model that is applicable to polygonal shaped particles. As the
contact condition of a particle is assumed to be restricted to only the other particles adjacent to it, its
dynamic response can be determined by solving its corresponding equations of motion, leading to an
efficient approach to determine the dynamic response of the granular medium. The use of the polygon
shaped particles adapts seamlessly with the SBFEM, which required for the subsequent stress analysis.
Each grain can be modelled by the SBFEM using only a single polygon. The stress state in a polygon
determines the particle breakage condition, dictated by a failure criterion e.g. Hooke-Brown criterion.
Once the breakage condition is detected, the resulting polygon is split into two. The resulting new
polygons are directly modelled by the DEM and the SBFEM without any change to the formulations.
The flexibility of both approaches therefore, adapts very well to the evolving geometries of the granular
medium during the loading process.
The feasibility of the developed method is demonstrated through parametric studies to highlight the role
of the particle breakage on the behavior of granular media at both the macro- and meso-scales.
Keywords:
- Correction
- Cite
- Save
- Machine Reading By IdeaReader
0
References
1
Citations
NaN
KQI