Experimental Validation Study of 3D Direct Simple Shear DEM Simulations
File(s)
Accepted version
Author(s)
Bernhardt, ML
Biscontin, G
O'Sullivan, C
Type
Journal Article
Abstract
Simple shear element tests can be used to examine numerous geotechnical problems; however, the cylindrical sample (NGI-type) direct simple shear (DSS) devices have been criticized for an inability to apply uniform stresses and strains, as well as the inability to fully define the stress state of the soil during shearing. Discrete element method (DEM) simulations offer researchers a means to explore the fundamental mechanisms driving the overall behavior of granular soil in simple shear, as well as improve understanding of the DSS device itself. Here three-dimensional DEM simulations of laminar NGI-type direct simple shear element tests and equivalent physical tests are compared to validate the numerical model. This study examines the sensitivity of the DEM simulation results to sample size, contact model and stiffness inputs, and ring wall boundary effects. Sample inhomogeneities are also considered by examining radial and vertical void ratio distributions throughout the sample. Both the physical experiments and the DEM simulations presented indicate that the observed material response is highly sensitive to the particle size relative to the sample dimensions. The results show that samples with a small number of relatively large particles are very sensitive to small changes in packing, and thus an exact match with the DEM simulation data cannot be expected. While increasing the number of particles greatly improved the agreement of the volumetric and stress-strain responses, the dense DEM samples are still initially much stiffer than the experimental results. This is most likely due to the fact that the inter-particle friction was artificially lowered during sample preparation for the DEM simulations to increase the sample density.
Date Issued
2016-05-19
Date Acceptance
2016-01-28
Citation
Soils and Foundations, 2016, 56 (3), pp.336-347
ISSN
0038-0806
Publisher
Elsevier
Start Page
336
End Page
347
Journal / Book Title
Soils and Foundations
Volume
56
Issue
3
Copyright Statement
© 2016, Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International http://creativecommons.org/licenses/by-nc-nd/4.0/
Subjects
Science & Technology
Technology
Physical Sciences
Engineering, Geological
Geosciences, Multidisciplinary
Engineering
Geology
Discrete element method (DEM)
Laboratory tests
DSS
Three-dimensional model
SPHERICAL-PARTICLES
FAILURE STATE
TESTS
SPECIMENS
APPARATUS
Geological & Geomatics Engineering
0905 Civil Engineering
Publication Status
Published