Degree Type

Dissertation

Date of Award

2017

Degree Name

Doctor of Philosophy

Department

Civil, Construction, and Environmental Engineering

Major

Civil Engineering

First Advisor

Jeramy Ashlock

Second Advisor

Mehari Tekeste

Abstract

Simulation of soil excavation is difficult. Tools which manipulate soil are difficult to evaluate in a virtual environment prior to prototype or manufacture. Soil behaves as a discontinuous material in normal excavation activities. Therefore, numerical methods which naturally model discontinuous media, such as the Discrete Element Method (DEM), can be used to perform simulations of soil excavation. However, DEM input parameters must be calibrated to accurately model the mechanical behavior of soil. The goal of this research was

to develop intelligent methodologies to calibrate DEM input parameters to reproduce the mechanical responses of soil and other granular materials subject to traditional laboratory tests, such as triaxial and direct shear tests. A mechanistic understanding of the interaction between sliding and rolling friction was developed and correlated with the critical state strength of drained granular media. In addition, the fundamental soil mechanics concept of relative density was successfully applied to the DEM calibration methodology to predict peak granular strength and dilatancy. Sensitivity analyses of DEM input parameters were used to enhance the characterization of mechanical behavior of DEM specimens. A calibration algorithm was developed to quickly and mechanistically relate DEM input parameters to laboratory measured mechanical behavior of soils. The algorithm eliminates unnecessary iterations during the DEM parameter calibration by enforcing a sophisticated understanding of the mechanisms of granular shear strength. The outcomes of this research greatly simplify the calibration of DEM parameters of soil for use in industrial excavation problems.

Copyright Owner

Zamir Imtiyaz Syed

Language

en

File Format

application/pdf

File Size

215 pages

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