Collaborative Research: A New Theory of 3D Particle Characterization

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Granular materials such as soils are prevalent in nature and broadly used as engineering materials for civil infrastructure (e.g., in dams, levees, roads and railways). 3D particle geometry is a key piece of information to fundamentally understand the granular material behavior subjected to static and dynamic loadings. While the 3D particle geometry is characterized in terms of four features, i.e., volume, surface area, size and shape, the characteristics of the 3D geometry can only be fully understood through the interrelationships of these four features. For example, there is limited understanding of how volume is related to surface area for random mineral particles. This relationship clearly depends on the particle shape as well (e.g., a sphere and an ellipsoid with the same volume have different surface areas). The relationship between these features is therefore key to comprehensively address the four-dimensional aspects of 3D particle geometry, which will enable the fundamental understanding of their combined influence on the behavior of granular materials and will help to better design civil infrastructure against natural hazards such as earthquakes. In addition, this project will develop educational modules for undergraduate classes by closely integrating with the research activities and by using recent advances in 3D printing and scanning technologies. The research team will incorporate the education modules into existing undergraduate level courses in geotechnical and materials engineering. This educational effort will provide a new model for successfully integrating knowledge discovery, teaching and learning in the area of granular materials.This project will develop a new theory for comprehensive 3D particle geometry characterization based on a new, simple formula that correlates the parameters defining the 3D particle geometry. This formula unravels the intertwined relationships between the four particle geometry parameters by expressing the 3D particle morphology as a function of surface area, volume and size. The study develops three research hypotheses to test the new theory step-by-step. The research will (i) characterize individual particles using the researched formula, (ii) characterize particle groups (i.e., granular material) in association with a power law relationship between the surface area and volume, and (iii) perform testing to investigate the relationship between the characterized geometric information using the new approach and various mechanical properties of granular materials, including dilatancy and strength.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.