Numerical simulation of the dynamic response of granular soils by means of the Discrete Element Method (DEM).

Abstract

Numerical methods are being implemented widely in geotechnical engineering; however, methods based on continuum mechanics are not able to provide microscale level information. Discrete Element Method (DEM) discretize the space into discrete particles and, through the analysis of micromechanical parameters that define the contact model, macroscopic behavior can be studied. DEM can capture the information at the particle level, and it has proven to be a valuable tool in the analysis of static and cyclic behavior of soils. In this study, an attempt of improving an existing calibration of the contact law parameters for Karlsruhe fine sand has been made to validate it for different testing conditions using DEM. Samples are prepared at target relative density and two types of boundary conditions are applied to explore its effect on DEM simulation. The contact law parameters for the sand are recalibrated based on the experimental results of Wichtmann and Triantafyllidis (2016). Under drained conditions, the numerical samples are able to replicate the volumetric change behavior, the dilative and contractive behavior and the initial stiffness of the experiment. The undrained behavior is examined by applying a constant volume method, where for the loose state there is a good agreement with the experimental results. Cyclic undrained results for dense samples correlates with the outcomes obtained under monotonic undrained conditions, showing a stiffer response than the experiment.