Micromechanics of Undrained Response of Dilative Granular Media 1 Using a Coupled DEM - LBM Model : A Case of Biaxial Test

16 In this paper the Discrete Element Method (DEM) is coupled with the Lattice-Boltzmann 17 Method (LBM) to model the undrained condition of dense granular media that display significant 18 dilation under highly confined loading. DEM-only models are commonly used to simulate the 19 micromechanics of an undrained specimen by applying displacements at the domain boundaries 20 so that the specimen volume remains constant. While this approach works well for uniform strain 21 conditions found in laboratory tests, it doesn’t realistically represent non-uniform strain conditions 22 that exist in the majority of real geotechnical problems. The LBM offers a more realistic approach 23 to simulate the undrained condition since the fluid can locally conserve the system volume. To 24 investigate the ability of the DEM-LBM model to effectively represent the undrained constraint 25 while conserving volume and accurately calculating the stress path of the system, a two 26