DEM simulation of granular materials under direct shearing considering rolling resistance

Series of biaxial compression simulations are carried out to investigate the effects of boundary condition on the deformation of granular materials by using DEM. The parameters used in DEM are validated by the biaxial compression experiments on elliptical steel bars. The effects of boundary condition on the stress-strain relationship are analyzed. And special focus are put in the analysis of particle displacement, particle rotation, void distribution, particle long axis orientation and contact force with the development of deformation.

Download Full-text

DEM simulation for shear behavior in unsaturated granular materials at low-stress state

Computers and Geotechnics ◽

10.1016/j.compgeo.2020.103551 ◽

2020 ◽

Vol 122 ◽

pp. 103551 ◽

Cited By ~ 1

Author(s):

Hyunbin Kim ◽

Seong-Wan Park

Keyword(s):

Stress State ◽

Granular Materials ◽

Shear Behavior ◽

Dem Simulation

Download Full-text

An expression for the angle of repose of dry cohesive granular materials on Earth and in planetary environments

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.2107965118 ◽

2021 ◽

Vol 118 (38) ◽

pp. e2107965118

Author(s):

Filip Elekes ◽

Eric J. R. Parteli

Keyword(s):

Particle Size ◽

Granular Materials ◽

Gravitational Force ◽

Rolling Resistance ◽

Critical Value ◽

Angle Of Repose ◽

Theoretical Expression ◽

Particle Interactions ◽

Planetary Environments ◽

Force Ratio

The angle of repose—i.e., the angle θr between the sloping side of a heap of particles and the horizontal—provides one of the most important observables characterizing the packing and flowability of a granular material. However, this angle is determined by still poorly understood particle-scale processes, as the interactions between particles in the heap cause resistance to roll and slide under the action of gravity. A theoretical expression that predicts θr as a function of particle size and gravity would have impact in the engineering, environmental, and planetary sciences. Here we present such an expression, which we have derived from particle-based numerical simulations that account for both sliding and rolling resistance, as well as for nonbonded attractive particle–particle interactions (van der Waals). Our expression is simple and reproduces the angle of repose of experimental conical heaps as a function of particle size, as well as θr obtained from our simulations with gravity from 0.06 to 100 times that of Earth. Furthermore, we find that heaps undergo a transition from conical to irregular shape when the cohesive to gravitational force ratio exceeds a critical value, thus providing a proxy for particle-scale interactions from heap morphology.

Download Full-text

Grain roughness effect on the critical state line of crushable sands

10.20933/100001234 ◽

2021 ◽

Author(s):

Jiangtao Lei ◽

◽

Marcos Arroyo ◽

Matteo Ciantia ◽

Ningning Zhang ◽

...

Keyword(s):

Granular Materials ◽

Critical State ◽

Roughness Effect ◽

Dem Simulation ◽

Dem Model ◽

Grain Roughness

A recently proposed DEM model for materials with rough crushable grains (Zhang et al. 2021; Ciantia et al. 2015; Otsubo et al. 2017) is here employed to examine the effect of contact roughness on the critical state line, a property of granular materials which is a) fundamental for the evaluation of liquefaction risk and liquefied responses and b) easily accessible through DEM simulation (Ciantia et al. 2019).

Download Full-text