Micromechanical observation of kinematics of sheared circular discs

TY - GEN

T1 - Micromechanical observation of kinematics of sheared circular discs

AU - Ali, Usman

AU - Kikumoto, Mamoru

AU - Cui, Ying

AU - Ciantia, Matteo

AU - Previtali, Marco

N1 - Funding Information: The Ministry of Education, Culture, Sports, Science, and Technology of Japan is acknowledged for providing financial assistance through the MEXT scholarship to the first author. This work was funded by JSPS KAKENHI under grants 24360192 and 19H00780. Support from the Royal Society IES/R1/201238 International Exchanges grant is also acknowledged.

PY - 2023/9

Y1 - 2023/9

N2 - Particle rolling is an essential microscopic mechanism that governs macroscopic behavior. This study conducts biaxial shearing tests on bi-dispersed circular discs at different confining pressures. A novel 2D image analysis technique is employed to measure the rolling of all the particles. It is observed that most of the particles exhibit significant rolling during shearing. Rollings are normally distributed in clockwise and counterclockwise directions, and the net rolling of the granular assembly is almost zero. Generally, the rolling of a particle is accompanied by its neighboring particles opposite rolling in a similar magnitude. In some cases, a group of particles is observed to exhibit rolling in the same direction, accompanied by another opposite rolling group in the neighboring regions. Particles inside the shear band tend to show significant rolling. The rolling rate is prominent at the beginning of the shearing and gradually decreases towards the end. Small particles exhibit significantly higher rotations, while larger particles are relatively resistant to rolling. Small particles work as ball bearings between two big particles, reducing the shear strength of the granular materials. The experimental data obtained in this study can be used to perform detailed validation of numerical models to simulate realistic granular behavior such as DEM.

AB - Particle rolling is an essential microscopic mechanism that governs macroscopic behavior. This study conducts biaxial shearing tests on bi-dispersed circular discs at different confining pressures. A novel 2D image analysis technique is employed to measure the rolling of all the particles. It is observed that most of the particles exhibit significant rolling during shearing. Rollings are normally distributed in clockwise and counterclockwise directions, and the net rolling of the granular assembly is almost zero. Generally, the rolling of a particle is accompanied by its neighboring particles opposite rolling in a similar magnitude. In some cases, a group of particles is observed to exhibit rolling in the same direction, accompanied by another opposite rolling group in the neighboring regions. Particles inside the shear band tend to show significant rolling. The rolling rate is prominent at the beginning of the shearing and gradually decreases towards the end. Small particles exhibit significantly higher rotations, while larger particles are relatively resistant to rolling. Small particles work as ball bearings between two big particles, reducing the shear strength of the granular materials. The experimental data obtained in this study can be used to perform detailed validation of numerical models to simulate realistic granular behavior such as DEM.

KW - Shearing

KW - circular discs

KW - rolling

KW - shear band

UR - https://www.issmge.org/publications/publication/micromechanical-observation-of-kinematics-of-sheared-circular-discs

M3 - Conference contribution

BT - Proceedings of the 8th International Symposium on Deformation Characteristics of Geomaterials (ISDCG2023)

A2 - Viana da Fonseca, António

A2 - Ferreira, Cristiana

PB - International Society for Soil Mechanics and Geotechnical Engineering

T2 - 8th International Symposium on Deformation Characteristics of Geomaterials

Y2 - 3 September 2023 through 6 September 2023

ER -