Field Applications of Induced Partial Saturation (IPS) for Liquefaction Mitigation NSF Project

Field Applications of Induced Partial Saturation (IPS)
for Liquefaction Mitigation
NSF Project

Overview:

During the past few years, there have been increased research efforts aimed at developing new and innovative liquefaction mitigation measures. Biological and chemical treatment techniques have shown good promise. The PI and Co-PI have been investigating the benefits of Induced Partial Saturation (IPS) as a liquefaction mitigation measure. IPS involves the injection and transport of a gas generating chemical solution in liquefaction susceptible sand, and through reactivity oxygen gas bubbles are generated in-situ, thus inducing partial saturation. The PI and Co-PI’s research results from tests on IPS treated small laboratory as well as large sand specimens in the laminar box of NEES@Buffalo (research that was funded by NEES/NSF) clearly demonstrated the technical feasibility of IPS as a liquefaction mitigation measure. These laboratory tests and an exploratory field test (collaborated with NEES@UT and NEES@UCSB) also identified the need to develop fundamental knowledge of IPS treatment and its benefits under real field conditions. The proposal addresses this need with the aim to develop IPS as a feasible field technique for liquefaction mitigation. After successful completion of this proposed phase of the research, the plan is to request funds to explore the benefits of IPS through field research in Christchurch, New Zealand.

Intellectual Merit:

The goal of the proposed research is to investigate IPS as a potentially feasible field technique for liquefaction mitigation. To achieve this goal, the following three primary research areas have been identified: 1) Behavior of IPS treated real sands under field conditions. In this task, the effects of sand gradation, particle size and shape, relative density, in-situ anisotropic permeability and its reduction due to gas generation, ground water quality and PH, and overburden stress, on induced partial saturation will be investigated, 2) Numerical simulation of IPS under field implementation. In this task, the software SUTRA-Bubble developed under the NEES/NSF grant will be expanded to simulate field implementation of IPS, using multiple injection and extraction tubes in heterogeneous soil profile with anisotropic permeability, and 3) Field treatment of sands by IPS: Test Bed. In this task, the Northeastern University suburban Dedham campus will be utilized as a test bed. The site has loose to medium dense sands and was used to a limited extent to test a portable drilling equipment purchased during the NEES grant. In this task, the knowledge gained from Tasks 1 and 2 will be verified in the field. A field electric conductivity probe for in-situ determination of degree of saturation will be developed and tested. A dynamic cone that was developed but not tested during the NEES grant will be improved and tested to explore its ability to evaluate the effect of IPS on in-situ liquefaction potential.

Broader Impact:

The outcomes of this research will advance IPS as a technically feasible and practical field technique for liquefaction mitigation. It will have a broad impact on reducing earthquake risk worldwide. The fundamental knowledge gained on inducing partial saturation and behavior of partially saturated sands can have a broader application in geo-environmental engineering practice. The developed electric conductivity probe to map in the field the spatial distribution of partial saturation can have benefits in general geotechnical, geotechnical earthquake, and environmental engineering practice. The PI and Co-PI will continue their active involvement in outreach and recruitment activities targeted to minorities and women, using the shaking table facility and their research outcomes. Annually, over 2000 middle and high school students and teachers go through the shaking table facility as part of College of Engineering Women in Engineering, Building Bridges, STEM Education, NSF Young Scholars and NSF PRISM programs. The PI and CO-PI are committed to continue disseminating their research results through variety of venues including technical publications, seminars, professional magazines, web-sites, and public media.