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New Method to Prevent Soil Liquefaction to Undergo Full-Scale Testing at UB
June 22, 2012
A new method to prevent soil liquefaction will undergo large-scale testing at the University at Buffalo (UB) as part of a three-year project funded by a $1.2 million grant from the National Science Foundation’s George E. Brown, Jr. Network for Earthquake Engineering Simulation (NEES).
Soil liquefaction typically occurs when shaking from an earthquake causes the pressure of water contained in sandy soils to greatly increase, resulting in a temporarily weaker soil that cannot support structures. Current methods used to mitigate the problem can be expensive and impractical for treating liquefied soils, especially for areas under existing buildings and bridges.
The NEES project, highlighted in ASCE’s May 2012 issue of Civil Engineering, involves the advanced testing of a new process called Induced Partial Saturation (IPS). The new method, which promises a more targeted and efficient way to treat affected areas under existing structures, works by pumping a solution into the otherwise liquefiable loose saturated soil that releases tiny bubbles of oxygen gas that, in turn, help create partially saturated soil. Sandy soils containing small amounts of such tiny gas bubbles are more resistant to liquefaction. Collaborators on the project include Northeastern University, UB, Boise State University and the University at Texas.
“This method is an improvement over existing methods because it is more economical and can be implemented even in a built environment under buildings,” says Sabanayagam Thevanayagam, Professor of Civil, Structural and Environmental Engineering, who is leading the research at UB. “In addition, the solution developed to be used in this process is environmentally friendly, so there is no concern about putting harmful chemicals in the ground,” adds Mishac Yegian, the Project Director and Professor of Civil and Environmental Engineering at Northeastern University.
Large-scale testing of the IPS process will take place in UB’s Structural Engineering and Earthquake Simulation Laboratory (SEESL) this summer. The tests will utilize the lab’s geotechnical laminar box, which was designed at UB for soil-foundation-structure interaction studies at or near full scale. With a depth of 6 meters and a capacity to hold 150 tons of sand, the box can simulate the effects of soil liquefaction in real-world ground conditions subjected to strong earthquake shaking.
Thevanayagam says the results of the geotechnical laminar box tests will be an accurate indicator of whether the process will be successful in the field. Once testing at UB is complete, field tests will be conducted at a NEES site in Southern California in an area that contains liquefiable soils and is prone to earthquakes. The outcome of this research could provide a valuable solution worldwide to one of the devastating and costly effects of earthquakes.
For more information, view the NSF Project Abstract for “Induced Partial Saturation (LPS) Through Transport and Reactivity for Liquefaction Mitigation.”
SEESL’s geotechnical laminar box, which can hold 150 tons of sand, will be used to simulate the effects of soil liquefaction.