Simulating the Elementary Behavior of Granular Materials Subjected to General Loading Paths

The discrete element method (DEM) plays an import role in the study of the constitutive relationship of granular materials by providing multi-scale data. It serves as an effective tool for numerical experiments, which however need to be conducted with care. The sample generated and tested in DEM is considered a representative volume element, which hence should be uniform. However, when loaded with frictional wall boundaries, as required to impose in-plane surface traction with controllable loading directions, arching develops near the corner. This paper addresses the effectiveness of using polyhedral specimens to reduce the arching-induced sample non-uniformity when running DEM numerical experiments to study the loading path dependence of granular materials. The previously proposed algorithm in Li et al. [1] has been implemented in the open-sourced software LIGGGHTS. Observations on the contact forces show that the samples become more uniform as the polyhedral specimen approaches a sphere. This study confirms the necessity of using polyhedral specimen shape when reproducing the elementary behaviour of granular materials subjected to varying loading directions.