As part of a five-year study, OU researchers will conduct an earthquake simulation in northeastern Oklahoma and attempt to learn more about how earthquakes affect bridge structures in quake-prone areas later this month.

Amy Cerato, OU assistant geotechnical engineering professor and researcher on the project, said she and her team hope to find a less expensive way to protect existing structures.

“It’s very expensive to go in and retrofit old bridges and buildings with new foundations,” Cerato said. “Our goal is to retrofit existing foundations with a cement deep soil mix to try to stabilize and strengthen those existing piles when earthquakes happen.”

Started in 2008, the project will kick into high gear with a large-scale field test set to occur sometime in mid-September when the cement is strong enough, said K.K. Muraleetharan, lead researcher on the project.

There are two steel pipes buried 21 feet at the test site, provided by Iowa State University. These steel pipes are called pile foundations, and they will be shaken by a simulator.

“We just have one shot, so that is what we are getting ready for,” Muraleetharan said. “The test pushes a simulator on top of the pile. One is in just regular clay, and one in regular cement so we can compare them.”

The whole idea of the project is to use cement to improve soft soil.

The team mixes cement with the soft layer of clay using a machine to introduce the cement and the water into the soil, said Gerald Miller, OU geotechnical engineering professor and researcher on the project.

“We’re looking to see how these piles behave when they are pushed laterally,” Miller said. “Miami was kind of the ideal site, just enough soft clay but not too much.”

The project is funded by a $1.2 million grant from the National Science Foundation and is set to expire in 2012, Muraleetharan said.

Iowa State, San Jose State University, Clemson University, Earth Mechanics Inc. and Advanced GEOSolutions Inc. are all involved in the project, with OU leading the way.

Along with field testing, the team is also conducting simulations in the world’s largest centrifuge at the University of California-Davis. Cerato and some of her graduate students were there last summer to run tests for the project.

“We put a small model into the centrifuge and spin it at a very high G,” Muraleetharan said. “While it is spinning, we shake the thing to see how it reacts.”

Through field testing, small model testing in centrifuges, and computer simulations, the team hopes to compile enough data at the end of its project to make useful recommendations.

“We want to educate the public and state transportation departments on how they can take care of their buildings and bridges during an earthquake,” Cerato said.

There are also plans towards the end of the project to create simplified analysis techniques and guidelines for the people who will be implementing bridge and structure construction in the coming years.

“The idea is to not do just tests. Eventually you have to bring that into some implementable guidelines,” Muraleetharan said. “That’s why we have two companies which are high-end consulting firms, one on ground modification and one on seismic design, as part of our team.”