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Field Application of IPS for Liquefaction Mitigation

July 7, 2016

CEE Professors Mishac Yegian and Akram Alshawabkeh were awarded a $342K NSF grant for "Field Application of Induced Partial Saturation (IPS) for Liquefaction Mitigation".

Abstract Source: NSF

Catastrophic effects of earthquakes on our built environment including, buildings, bridges, dams, and power plants, are often caused by ground failures due to soil liquefaction. Liquefaction refers to the loss of bearing capacity of saturated sandy soils to support structures during earthquakes. Existing techniques that can be used to prevent occurrence of liquefaction are very costly and can only be implemented at new sites and only at existing structures. There is a critical need to develop a cost-effective and practical liquefaction prevention technology that can be applied to new sites as well as sites with existing structures resting on liquefiable soils. This research will explore advancing an innovative concept referred to Induced Partial Saturation (IPS) in which water saturation of a liquefiable sands is reduced, thus preventing its failure during earthquakes. Induced Partial Saturation involves injection of a gas generating chemical solution into the liquefiable sandy ground, leading to controlled generation of oxygen gas bubbles within the pores of the sand through transport and reactivity of the solution, thus reducing water saturation in the ground. Research conducted by this team at Northeastern University demonstrated that partial saturation of sands indeed prevents the occurrence of liquefaction. The outcome of this research will advance IPS as a technically feasible, practical, and cost-effective field technique for liquefaction mitigation. IPS will have broad impacts, including reducing earthquake risk worldwide. Also, the fundamental knowledge gained will have significant benefits in enhancing technologies for remediation and restoration of contaminated groundwater, a major problem with significant impacts on human health. Furthermore, this research will continue to create unique opportunities for middle and high school students and teachers to participate in activities in the researchers' earthquake engineering laboratory, promoting science and engineering through demonstrations and hands-on structural model creation and testing. The research outcomes will be published and made available through the researchers' website. The data and finding of this research will be uploaded to the NSF-supported NHERI Data Depot.

The goal of this research is to investigate and advance Induced Partial Saturation as a feasible field technique for liquefaction mitigation. To achieve this goal, the following three primary research tasks will be conducted: 1) Evaluation of behavior of liquefaction susceptible field sands treated by IPS, 2) Development of numerical simulation to model the IPS process under real field conditions, and 3) Evaluation of the performance of field experiments at a testbed at the Dedham campus of Northeastern University to advance fundamental knowledge on IPS treated sands and to verify the developed numerical simulation. The research tasks will lead to new fundamental knowledge on inducing partial saturation under real field conditions, and on the behavior of field sands to IPS treatment. The research will also create opportunities to develop field tools and methods for implementation of IPS as well as numerical simulation software to determine design concepts and parameters for field application of IPS as an earthquake liquefaction mitigation measure.