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EVALUATION OF CRUSHING IN GRANULAR MATERIALS USING THE DISCRETE ELEMENT METHOD AND FRACTAL THEORY

by Lobo-Guerrero, Sebastian

Abstract (Summary)
Granular materials forming part of embankments, foundations, pavement structures, and rail track structures are subjected to both static and dynamic loads. As a result of these loads particle breakage may occur. Particle breakage causes settlements and a reduction in the hydraulic conductivity of the granular material. Moreover, the elastic modulus and the shear strength of the granular material are also negatively affected. Granular crushing is a detrimental phenomenon that deserves to be sudied in order to understand its causes, consequences, and ways to avoid it. Laboratory tests conducted on a weak granular material (sugar) and computer simulations (in the form of the Discrete Element Method, DEM) were used to visualize, analyze, and understand the evolution of crushing in granular materials. The original DEM was modified to include the possibility of particle fragmentation. A tensile failure criterion developed by the author was programmed and incorporated into a commercial DEM code (PFC2D). The breakage model was also used to study the evolution of crushing in practical geotechnical applications. Fractal theory was used to quantify the amount of crushing produced under different conditions of stress and strain. In particular, the fragmentation fractal dimension was used to describe the changes on the grain size distribution of the analyzed materials.
Bibliographical Information:

Advisor:Luis E. Vallejo; Julie M. Vandenbossche; Ian Nettleship; Jeen-Shang Lin

School:University of Pittsburgh

School Location:USA - Pennsylvania

Source Type:Master's Thesis

Keywords:civil and environmental engineering

ISBN:

Date of Publication:06/02/2006

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