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Doctoral Research:

Aging of Granular Geomaterials and Contact Maturing Under Multiphysics Conditions (University of Michigan, Ann Arbor)

 

Funding:

National Science Foundation, Awards #1129009 & #1537222

RC Hurt Doctoral Fellowship, University of Michigan

Rackham Graduate Student Travel Grant, University of Michigan

Rackham Graduate Student Research Grant, University of Michigan

Itasca Educational Partnership Grant, Itasca Consulting Group, MN

Summary:

For more than three decades, sand has been observed to alter its engineering properties over time, but no consensus has been reached on the driving mechanisms behind this phenomenon. The aging process in sand has been observed to be sensitive to multiphysics conditions, including the presence and chemical content of pore fluid, temperature, and the mechanical loading. An better understanding of the mechanisms of this process is of vital importance to the advancement of some key areas in civil engineering, including renewable energy, geological CO2 sequestration, foundation stability, and natural hazards mitigation. In the center of this study is a static fatigue hypothesis which states that delayed fracturing of micro-morphological features on grain surfaces at contacts, such as asperities and mineral debris, is a key contributor to aging of silica sand.

Objective: 

  • Investigate what are the mechanisms of sand aging in multiphysics conditions by testing the static fatigue hypothesis, by means of a combination of experimental and numerical methods.

Key Results: 

  1. Micro-scale laboratory experiments were conducted to study time-dependent response of inter-grain contacts under sustained loads; they produced the first set of data of its kind.

  2. Laboratory experiments on sand grain assemblies were performed to provide evidence that the contact behavior induces aging effects in sand; factors affecting rates of aging, such as loads, pore fluid acidity and grain sizes were explored.

  3. Simulations of a single inter-grain contact were performed with the distinct element method, and possible consequences of contact fatigue/maturing were demonstrated.

  4. Finally, a preliminary finite element framework was developed to explore the evolution of grain surface textures to shed light on the effects of pore fluid chemistry on aging rates. 

Journal Publications:

  1. Michalowski, R.L.*, Wang, Z., Nadukuru, S.S., Mesri, G., and Kane, T. (2019). Maturing of Contacts and Ageing of Silica Sand. Géotechnique, 69(8), pp.748-749. (DOI: https://doi.org/10.1680/jgeot.18.d.004).

  2. Wang, Z. and Michalowski, R.L.* (2018). An Apparatus for Testing Static Fatigue at Sand Grain Contacts. Geotechnical Testing Journal, 41(3), pp.448-458. (DOI: https://doi.org/10.1520/gtj20170251). 

  3. Michalowski, R.L.*, Wang, Z., and Nadukuru, S.S. (2018). Maturing of Contacts and Ageing of Silica Sand. Géotechnique, 68(2), pp.133-145. (DOI: https://doi.org/10.1680/jgeot.16.p.321).

  4. Wang, Z. and Michalowski, R.L.* (2015). Contact Fatigue in Silica Sand—Observations and Modeling. Geomechanics for Energy and the Environment, 4, pp.88-99. (DOI: https://doi.org/10.1016/j.gete.2015.07.003). 

micro_aging-01.png

Above: Particle-Scale Experiments

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Above: Mesoscale Experiments

aging_DEM_GETE-01.png

Above: Discrete Element Modeling of Contact Maturing (Microfracturing) at Microscopic Scale

Contact

Zhijie Wang
3700 O'Hara St., Pittsburgh, PA 15261
Email: zhijiewang@pitt.edu
Website: http://www.zhijiewang.org

©2024-2026 by Zhijie Wang

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