Oral comprehensive exam mahdi

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Application of gravitational sphere packing method to study the inner structure of packed soil particles

Student: M. Mahdi RoozbahaniAdvisor: Dr. J. David Frost

Geosystem Engineering Group, School of Civil and Environmental Engineering

Georgia Institute of Technology

Oral Portion of the Comprehensive Ph.D. Examination23 January 2015

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Motivation of the research

• To develop a computationally efficient and rapid technique to pack multi-sized spherical and non-spherical particles.

• To examine boundary effects. Many of the geotechnical experiments are affected by the boundary effects.

• To explore the complex geometrical shape of pore structure.

• To apply artificial intelligence approaches to speed up numerical calculation of soil properties with the high computational demands (permeability, tortuosity, …)

Gravitational Sphere Packing (GSP)

[AR Fuggle, et al, 2014]

Binary Packing with Size Ratio = 2.8

- Non-spherical particles (sphere clump)?

- Shaking process?3

Boundary Effects

[Roozbahani et al, 2014]

Mono-sized packed particles (Container size / Particle size = 10)

Boundary effects in loose and close sphere packing with different particles’ sizes?

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Complex geometrical shape of pore in a 2D case

• Finding the complex pore geometry in 3D using Euclidean Distance Transform (EDT) ?

• How particle size and shape change pore geometry?

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Applying an optimized

algorithm of local maxima

Nearest Neighbors Algorithm

EDT

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Artificial intelligence approach

A graphical abstract how to employ GSP to predict soil properties by considering the comprehensive information attained by spatial statistics.

Intellectual Merit

• Applying GSP to study different properties of packed soil particles.

• Integrating computer science techniques into geotechnics. Such as: Machine Learning, network or graph analysis, …

• To develop rapid and accurate techniques to compute packed soil properties, and validate them with the trivial cases.

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Broader Impacts

• Filter Media (water purification, drainage system)

• Soft Matter (viscosity - rate of motion is a function of packing)

• Agriculture (Fruit Packing)

Thank You!

Publications:

Fuggle, Andrew R., M. Mahdi Roozbahani, and J. David Frost. "Size Effects on the Void Ratio of Loosely Packed Binary Particle Mixtures." Geo-Congress 2014 Technical Papers@ sGeo-characterization and Modeling for Sustainability. ASCE.

Roozbahani, M. Mahdi, Lori Graham Brady, and J. David Frost. "Mechanical trapping of fine ‐particles in a medium of mono sized randomly packed spheres." ‐ International Journal for Numerical and Analytical Methods in Geomechanics (2014).