Novel Approach for Generating Homogeneous Samples for Discrete-Element-Method Studies

A novel approach--the modified multilayer method--is proposed for generating homogeneous specimens for discrete-element-method (DEM) studies. The "particle boundary" is introduced at the interface between the layers, and the general servocontrolled technique is extended to the particle boundary to apply the stress field. Each layer of the specimen is compacted by moving the top and bottom boundaries simultaneously to generate the desired DEM specimen. Unlike existing methods, the proposed approach generates highly homogeneous specimens. The mechanism underpinning the new approach was determined by investigating the effect of the boundary movement on the final spatial distribution of the particles. A comparison with experimental direct-shear results shows that homogeneous samples generated using the proposed approach can accurately model the deformation and strength of granular material, whereas other methods lead to deviations due to sample inhomogeneity.