Validation of ellipse-based discrete element modeling in soil mechanics

The Discrete Element Method (DEM) is a numerical technique that models granular materials as distinct particles, rather than as a continuum. This thesis pertains to the validation of an ellipse-based DEM model developed to study the effect of particle shape on the deformational mechanisms and mechanical behavior of granular materials. An analysis of alternatives to the contact force-deflection relationship suggests that a simple linear contact relationship yields realistic macroscopic mechanical behavior.; Validation of the DEM model consisted of comparing physical test results with numerical DEM test results. Good agreement is found with the physical tests performed by Chapuis on slightly out of round disks. Comparison with the physical tests performed by Konishi et al on oval rods was less successful. In general, the DEM tests yielded strengths which were in the range expected for real soils, but were lower than the physical tests of Konishi et al. It is proposed that particle shape differences are responsible for discrepancies between Konishi and DEM test results.; To determine if the ellipse-based DEM model can be used to model full scale geotechnical problems, a shallow foundation is analyzed at two levels of embedment. Comparisons with analytical elastic solutions and Terzaghi bearing capacity theory suggest that the ellipse-based DEM technique can be used to model full scale geotechnical systems.