Soil framework earns researcher prestigious medal for the second time
For a geological engineer, “soil” isn’t really a singular noun. Rather, it’s a complex system of particles and the liquids and gases that move among them, making for mechanical behavior that’s highly challenging to predict and understand with much precision.
Civil and Environmental Engineering and Geological Engineering Associate Professor William Likos has spent much of his career creating theoretical frameworks to conceptualize the volatile geometry and physics at play in unsaturated soils. These efforts have now twice earned him one of the most prestigious awards in his field.
Likos has been awarded the Norman Medal from the American Society of Civil Engineers for his paper “Pore-scale model for water retention and fluid partitioning of partially saturated granular soil.” Published in May 2013 in the Journal of Geotechnical and Geoenvironmental Engineering, the paper represents an advance in understanding soil at a very minute level.
"It's a step toward recognizing that soil is a system of particles rather than a continuous solid,” Likos says. “It's a step toward looking at soil behavior on the scale that really matters—the microscopic scale.”
The paper’s other significant attribute is that it conceptualizes soil as a multi-phase material—not one solid but in fact an every-varying interaction among solids, liquids, and gases. “What this paper does is propose a model where we can differentiate these phases at the pore scale,” Likos says. His next steps will be to use the paper’s framework to better understand several nuances of soil that interest him. He has already used it for a paper exploring how heat moves through partially saturated soils.
Likos previously won the Norman Medal in 2007, while on the faculty at the University of Missouri, for a paper that offered a framework for understanding how changes in moisture affect soil’s strength and volume. Now, he is the only UW-Madison faculty member to receive the Norman Medal, and one of very few people to have earned the award twice—no small feat, considering the award has been given out since 1872.
“That’s really a tremendous honor, to be on the same list as the people who are on that list,” Likos says.
One reason Likos’ frameworks are so valued in the field is that geological engineers are still trying to fully grasp some very basic aspects of soil behavior, such as why soil becomes weaker when it gets wetter. “It’s a simple question, but something we don’t really have a handle on right now,” he says.