HR: 17:15h
AN: T14B-06    [Abstracts]
TI: Particle-scale processes associated with shear localization in granular materials
AU: * Rechenmacher, A
EM: arechenm@usc.edu
AF: University of Southern California, Dept. of Civil Engineering 3620 S. Vermont Ave, Los Angeles, CA 90089-2531 United States
AB: A digital imaging-based experimental technique, Digital Image Correlation (DIC), has been used to evaluate local displacement and strain processes associated with shear localization in sands. The digital nature of the DIC technique, and its underlying mathematical robustness, have made possible the acquisition of full-field displacement measurements to micrometer accuracy, with essentially grain-scale spacing between measurement points. Local strains were computed from the full-field data. Consistently, repeating patterns of alternating low and high magnitudes of shear strain, spin tensor components, and perpendicular displacement components were observed along localized zones, the patterns and spacings of which suggest a strong tie to the grain scale as a fundamental length scale. The results offer strong evidence of the notion of "buckling columns" as the primary physical mechanism supporting continuing shear in a granular medium. Previously, such a pattern has only been detected in numerical experiments. The results show strong potential for providing insight regarding the physical mechanisms responsible for the development, evolution and interplay among boundary, oblique and low-angle sub-shearing patterns that are often seen in numerical and experimental simulations of artificial fault gouge.
DE: 8163 Rheology and friction of fault zones (8034)
SC: Tectonophysics [T]
MN: Fall Meeting 2005