A Micromechanical Investigation of Instability in Particulate Media
Final technical rept. 1 Apr 93-31 Mar 97
UNIVERSITY OF SOUTHERN CALIFORNIA LOS ANGELES DEPT OF CIVIL ENGINEERING
Pagination or Media Count:
The main research objective is to investigate the microscopic origins of shear band instability in particulate media. Our methodology combines computational micromechanics, laboratory experiments, and continuum mechanics. The particular research objective are 1 to improve the existing methods of computational micromechanics, 2 to examine the formation of shear bands, 3 to investigate the effects of grain rotation on shear strength and shear bands, 4 to study liquefaction instability, and 5 to explore the micro-macro mechanics transition relevant to material instability. Stereophotogrammetry was found to yield an accurate measurement of the motion of a large number of particles of idealized granular media. The stereo-technique was capable of determining not only the displacement and rotation of particles, but also their relative penetration. This optical technique was found to be more accurate than the present computer vision methods being processed, are to be used to re-examine the findings about the effects of higher-order continua on the response of granular media, and are therefore instrumental to understand the instability phenomena in granular media.