Revealing Soil Mechanics via Coupled Discrete and Finite Element Method Triaxial Testing

This study presents a comprehensive investigation into the mechanical behavior of granular soils through a combined experimental and computational approach using triaxial testing and a coupled Discrete Element Method-Finite Element Method (DEM-FEM) framework.By integrating laboratory experiments with advanced numerical simulations, the research aims to enhance the realism and accuracy of soil behavior modeling under varying stress conditions.The use of flexible membrane modeling, realistic contact laws, and a coarse-graining strategy allows for detailed exploration of particle-level interactions and their influence on macroscopic deformation.Three coarse-graining coefficients (CGC = 3, 6, and 12) were evaluated to assess the trade-offs between computational cost and accuracy.The findings reveal that while higher CGC values improve efficiency, they introduce numerical artifacts, whereas lower CGC values deliver better alignment with experimental results at greater computational expense.CGC = 6 emerges as the optimal compromise, maintaining strong agreement with experimental stress-strain and volumetric responses across multiple confining pressures.The study also confirms that normalized stress-strain relationships are preserved across scales, validating the robustness of the DEM-FEM framework.Overall, this research offers a valuable methodology for bridging micro-and macro-scale mechanics in computational geotechnics and provides guidance on optimizing model resolution for practical engineering applications.