Bridges under pressure

Scientists at the University of California (UC), Davis have compiled the most detailed experimental data yet seen on how liquefaction-induced downdrag can add to the structural load applied to a pile foundation during earthquake shaking.

Their dataset was awarded a 2022 DesignSafe Dataset Award, which recognized the dataset's diverse contributions to natural hazards research.

The dataset was also made publicly available on the NHERI DesignSafe cyberinfrastructure.

"This research will help in predicting how much settlement pile foundations will have if piles go through liquefiable deposits," said dataset co-author Bruce Kutter, a professor emeritus at UC Davis.

"Our research also helps our understanding of this phenomenon move more strongly in a direction where we can account for the and the structure as a system from the foundation, all the way to the superstructure," said dataset co-author Katerina Ziotopoulou, an associate professor at UC Davis.

Modern bridges are supported by large columns called piles that are driven deep into the ground. Liquefaction, which is the loss of soil strength due to the development of excess pore water pressures during earthquake shaking, can make the normally stable sand layer under the bridge pile lose their shear strength.

A soil-pile-bridge system dataset was awarded a 2022 DesignSafe Dataset Award. It investigates how liquefaction-induced downdrag can add to the structural load applied to a pile foundation during earthquake shaking. The data was generated by inducing liquefaction in scale soil models in the University of California, Davis Geotechnical Centrifuge. Their dataset includes two well-documented experiments, one with uniform and the other with interbedded liquefiable deposits. Credit: Sinha et al.

Left: Sumeet and Bruce inspecting the model (from the SKS02 test) after testing and gradually excavating. Right: Sumeet, Bruce and Katerina next to consolidation press preparing the model for SKS02. Credit: Sinha et al.

Close-up of excavated model showing evidence of sand boil due to liquefaction going through the impermeable crust. Credit: Sinha et al.