The Wallace Hayward Baker Award, established in 2000 by the Geo-Institute of the American Society of Civil Engineers, is given to an individual who demonstrates “ingenious innovation in the field of ground modification.” Ingenious innovation is what Wally Baker was known for, a fact that this year’s recipient knows on a personal level.
Kyle Rollins, a Brigham Young University professor of civil engineering, is the 2018 recipient of the award. Rollins’ father taught Wally Baker in college at BYU, and so, for Rollins, earning this recognition in innovation in ground modification is not only a culmination of earned praise for hard work, but it’s also a lifelong dream.
“[Getting this award] is a big honor,” Rollins said. “My dad would always speak highly of Wally Baker and all the good things he was doing, and I always wanted to be like that someday.”
In his more than thirty year career as a civil engineer, Rollins certainly has accomplished a lot of good. His work on ground modification is making a big difference in the world of construction. Rollins has worked to improve good ground conditions for building on in three distinct ways: keeping collapsible soils from settling too much, improving horizontal resistance in soft soils, and preventing liquefaction damage.
“There are a lot of problems that can happen when you try to build something like a dam or an embankment for a roadway or a high rise structure,” Rollins said. “Sometimes, to combat the potential for collapsible soils, we’ll put deep columns of steel or concrete down into the earth. That can solve the problem, but it is really expensive. Trying to use a cheaper alternative doesn’t always work. The millennium tower in San Francisco that’s tilted eight degrees or so is a prime example of using a cheaper alternative that doesn’t work.”
Different types of soil require different approaches of improvement. Collapsible soil, for instance. If collapsible soil gets wet, a ten-foot layer of it could sink down a whole foot. Building anything on top of soil like that would be disastrous. To try and fix this issue in a more cost-effective way, Rollins and his team worked on developing deep dynamic compaction.
“Deep dynamic compaction means we’ll drop weights down on the surface, which will compact the surface and send a stress wave down that compacts the soil deeper into the ground,” Rollins said. “These weights might be 30 tons and are dropped from about 70 feet in the air repeatedly. We drop it in a grid pattern, every eight feet we’ll drop it, then move it, then drop it again.”
Dropping these weights creates craters that need to be filled, but Rollins and his team have developed equations to predict how deep the craters will be so they know how much material will be needed to fill them. But at the end of the day, deep dynamic compaction can negate any collapsible potential in soils fifteen to twenty feet below the surface, so any craters are well worth the results.
The next type of ground modification Rollins worked on deals with improving horizontal resistance in soft soils. Rollins said there’s a lot of soft clay-soil like this in the valleys in the Western United States.
“If we have soft soil, we have to resist horizontal forces from earthquake loading,” Rollins said. “The usual way to handle this type of soil is to drill steel columns down into the earth. To strengthen them, we can use additional steel columns, but we have to pay the cost of putting them down and patching them all together. I had the idea to try and improve the ground around those existing piles so that we can save money and not have to put more steel columns in.”
Some of his ideas included mixing the soil with cement and creating gravel columns down the side of the soil. With this type of soil, they only needed to improve the horizontal resistance about five to ten feet deep. To try out their ideas, Rollins and his team conducted tests.
“We did testing out in the west side of Salt Lake Valley,” Rollins said. “When we build embankments in Salt Lake Valley it will probably settle 2 or 3 feet. The soil is really compressible. We tested soil with and without the treatment method we’d developed. We increased the capacity by 170,000 lbs., a total of 60 percent increase. We did this kind of testing using a variety of different strategies and produced a report that people now reference for their own projects.”
The final ground condition Rollins and his team combated is liquefaction. Liquefaction occurs when the soil turns into quicksand during an earthquake. Rollins talked about an earthquake sequence in New Zealand that included several earthquakes of magnitude six or higher. The liquefaction was so extensive that it caused buildings to settle and cars to sink into the ground.
“There were about 140,000 properties damaged, and 51,000 of those were due to liquefaction,” Rollins said. “New Zealand needed to recover; they had 40 billion dollars’ worth of economic impact and 13 billion of that was due to liquefaction. Fifteen thousand homes were condemned. They knew they needed to reconstruct, but how were they going to do it economically?”
They eventually decided on a plan to improve a ten- or twelve-foot-deep layer of soil in the hopes that building a house on top of that would still stand, even with the ground ten or so feet below it being liquefied. They asked Rollins and his team to help them with a study to test that idea. The largest challenge the team faced was figuring out how to test something like that, large-scale.
“You can put some instruments in the ground and hang around until and earthquake hits,” Rollins said. “Or you can do a little scale model that people may or may not believe. The strategy we settled on was to set off small explosive charges in the ground to simulate an earthquake. Then we could add foundation elements in the ground, so once that soil is liquefied, we can push the foundations around and see how they behave.”
They tested their experiment results by shaking the ground layer of soil after the explosions went off to see if the foundations were secure. They were.
With resounding success in each ground modification technique he’s designed, Rollins is quite worthy of the Wallace Hayward Baker Award. But he isn’t going to take all the credit for this achievement.
“Each project I’ve talked about has three or four students behind it,” he said. “The quality of the students at BYU is exceptional. The students are the people that really drive this work.”