HR: 1340h
AN: MR23B-1331    [Abstracts]
TI: Fabric and Elastic property evolution in a Granular Dynamics based sedimentation model
AU: * Sain, R
EM: ratnas@stanford.edu
AF: Dept. of Geophysics, Stanford University, 397 Panama Mall, Stanford, CA 94305-2215, United States
AU: Mukerji, T
EM: mukerji@pangea.stanford.edu
AF: Dept. of Geophysics, Stanford University, 397 Panama Mall, Stanford, CA 94305-2215, United States
AU: Mavko, G
EM: mavko@stanford.edu
AF: Dept. of Geophysics, Stanford University, 397 Panama Mall, Stanford, CA 94305-2215, United States
AB: We study the evolution of fabric and elastic properties of a granular pack during a computationally modeled deposition and compaction process. We consider a random pack of spherical quartz grains and simulate gravity sedimentation and compaction using a granular dynamics simulation. We focus on studying the interrelationships between fabric and elastic properties near the critical porosity which is difficult to model in laboratory experiments. In the deposition model, the normal grain interactions are modeled by a visco-elastic contact law and shear interactions by a tangential elasticity model. We estimate the elastic properties of the pack using both finite element and granular dynamics calculations at intermediate stages of the simulation. For the fabric properties, we characterize pore space created by the grains using a second rank fabric tensor. The fabric tensor also gives an estimate of the fabric anisotropy in the pack. We find that the elastic properties near the critical porosity depend more on the grain rearrangements and less on the confining pressure. We also investigate the relation between fabric anisotropy and coordination number. We observe that the fabric tensor has transverse isotropy symmetry at the end of the simulation. The use of this process-based depositional simulation helps us in conducting numerical experiments to complement laboratory results in the study of loose unconsolidated sediments.
DE: 5102 Acoustic properties
DE: 5112 Microstructure
DE: 5114 Permeability and porosity
DE: 8168 Stresses: general
SC: Mineral and Rock Physics [MR]
MN: 2007 Fall Meeting