Modeling a Flexible Membrane for Triaxial Tests with Coupled FDM–DEM : Considering Realistic Particle Shape Effects

Particle morphology plays a crucial role in determining the mechanical behavior of granular materials. This paper focused on investigating the effects of boundary conditions on the triaxial mechanical properties of soil samples, with particular consideration given to the influence of particle shape. To achieve this, a numerical model was proposed, which couples the finite difference method (FDM) and the discrete element method (DEM) to simulate the behavior of a rubber membrane and soil particles, respectively. The particle morphology was accurately reconstructed using spherical harmonics (SH) analysis, and the shell cells in the FDM were utilized to construct the boundary modeling. Through a series of simulations, the macroscopic and microscopic mechanical responses of soil particles, both within and outside the shear band, were investigated. The obtained simulation results were then compared with those derived from the DEM simulation using a particle-based membrane. The research findings pertaining to the influence of boundary conditions and particle shape provide significant contributions to our understanding of granular material behavior. These findings offer valuable insights that can be applied in the design and analysis of geotechnical structures. © 2024 American Society of Civil Engineers.