Wednesday  |  Conference Center B  |  10:00 AM–10:20 AM

#13553, Constitutive Behavior of Granular Media under Cyclic Loading

The investigation of granular materials under cyclic loading is of great importance in a wide range of geotechnical applications. Examples of cyclic loading include wind and waves acting on land and offshore structures, earthquakes inducing cyclic shearing of soil, soil compaction, and rover wheels interacting with the Mars regolith. Much research has been devoted to understanding the mechanical response of granular materials subjected to cyclic loading conditions, yet this behavior is still not well understood at the grain scale. Granular mechanics has traditionally relied on the Discrete Element Method (DEM), a numerical technique that simulates granular media as a collection of particles and extracts grain-scale micromechanical information such as contact forces and kinematics. DEM, however, is computationally expensive, limited to simple grain shapes, and very qualitative. In this study, a recently developed technique called Granular Element Method (GEM) is used to study the micro- to macroscopic response of granular materials under cyclic loading. GEM uses a combined mathematical framework with experimental data to infer contact forces of granular assemblies despite grain shape, texture, and opacity. Cyclic loading is performed on a two-dimensional analog granular assembly at different shearing rates. Digital Image Correlation (DIC) is used to determine the granular assembly's full-field kinematics, and image processing is conducted to obtain information about the grain shape, contact, and centroid locations. Together, these experimental data become inputs to GEM, allowing for the extraction of force chains, which enables relating the macroscale constitutive behavior to grain scale geometry and properties.

Amanda Toledo Barrios   California Institute of Technology
Jose Andrade   California Institute of Technology
Guruswami Ravichandran   California Institute of Technology