Devastating effects of ground failure, due to liquefaction of water saturated sands, on the built environment has been widely observed during most moderate to large size earthquakes. There is an urgent need to develop a cost effective liquefaction prevention method that can be applied to new sites as well as sites with existing structures. Researchers at Northeastern University, the University of Texas at Austin, Boise State University, the University of California at Santa Barbara, the University at Buffalo and the USGS will collaborate to develop an innovative and practical field technique for liquefaction mitigation by inducing partial saturation (IPS) in otherwise fully saturated liquefiable sands. The goals of this research are twofold: 1) to conduct fundamental research exploring the feasibility of inducing partial saturation under field conditions, by injecting very low concentration of sodium percarbonate solution, and through transport and reactivity slowly generate oxygen gas bubbles in sands; and, 2) to demonstrate the effectiveness of IPS in preventing the occurrence of liquefaction. The research will take advantage of unique experimental and field facilities of NSF's Network for Earthquake Engineering Simulation (NEES) to acquire fundamental knowledge on the behavior of partially saturated sands and to develop enabling technologies to verify the effectiveness of IPS as a liquefaction prevention method. The research program will achieve its goal by integrating small- and large-scale laboratory investigations, field tests and numerical simulation. NEES facilities to be utilized are the 1-g laminar box at NEES@Buffalo, the T-Rex shaker at NEES@Utexas and the wildlife field site at NEES@UCSB. Data from this project will be archived and made available to the public through the NEES Project Warehouse/data repository.
The outcome of this research will have world-wide impact on human safety and protection of property from earthquake hazards. Also, this research will enhance oxygen delivery systems used in bioremediation of contaminated ground. The research is a collaboration between faculty and students in the fields of earthquake and geoenvironmental engineering. Such collaborations will benefit undergraduate and graduate students in science and engineering and promote interdisciplinary education and research. Educational tools using the research facility will be developed to heighten the public's awareness of earthquake risk and promote interest in science and engineering to underrepresented communities. This award is part of the National Earthquake Hazards Reduction Program (NEHRP).
Preventing Ground Failure Due to Liquefaction During Earthquakes Devastating effects of earthquakes on the built environment are often due to ground failure associated with liquefaction. Liquefaction is loss of bearing capacity of water-saturated sandy soils leading to failure of engineered structures. While a number of measures to prevent liquefaction have been developed in practice, such mitigation techniques are often very costly and inapplicable to sites with existing structures. The National Science Foundation has awarded Northeastern University a $1.2M research grant to develop an innovative, cost-effective, and practical field technique for liquefaction mitigation. Small- and large-scale laboratory and field tests have demonstrated that generating gas bubbles in saturated sands, thus inducing partial saturation (IPS), prevents the occurrence of liquefaction during earthquakes. Also, minute gas bubbles, once introduced within the void spaces of sands, remain entrapped even under strong ground shaking. This research has advanced the IPS technique to field applications, which involves injection of a solution with very low concentration of an eco-friendly chemical, and through ground water flow and chemical reactivity slowly generate oxygen gas bubbles within a fully saturated liquefaction susceptible sand deposit. The development and implementation of this cost-effective and practical field technique for prevention of ground failure due to liquefaction will have world-wide impact on human safety and protection of property from earthquake hazard. A provisional US patent of IPS has been secured. The research program is under the directorship of Profs. Yegian and Alshawabkeh at Northeastern University, in collaboration with Prof. Thevanayagam of State University of New York at Buffalo, Prof. Stokoe of the University of Texas at Austin, Dr. Steidl of the University of California at Santa Barbara, and Prof. Youd, formerly at Bingham Young University. The research utilized the unique experimental and field facilities of NSF's George E. Brown Jr. Network for Earthquake Engineering Simulation (NEES). This award was part of the National Earthquake Hazard Reduction Program (NEHRP).
