CAREER: Passive Site Remediation for Mitigation of Liquefaction Risk - From Concept to Technology

Drexel University, Philadelphia PA

Investigators

Abstract

"Passive Site Remediation for Mitigation of Liquefaction Risk - From Concept to Technology" The overall objective of this CAREER award is to demonstrate the practical feasibility of a new concept using passive remediation to mitigate the risk of soil liquefaction at critical facilities and lifelines; and concurrently to incorporate education and outreach activities that will increase public awareness, and especially that of female students of the challenges of engineering in general, and geotechnical and geoenvironmental engineering in particular, and to engage the students' excitement and creativity in solving complex engineering problems. Passive site remediation is integrally related to groundwater processes, including transport of stabilizers through the groundwater (the inverse of contaminant transport). The idea is to slowly inject a stabilizing material at the up-gradient edge of a site and deliver the stabilizer to the liquefiable area using the groundwater flow. Extensive soil liquefaction occurred in the 1995 Kobe earthquake, especially at the Kobe Port. The cost of repair has been estimated to be more than $11 billion, and the port operations were essentially halted for months. Of particular concern are developed sites where traditional ground improvement methods are difficult or impossible to implement. The aim of the project is to demonstrate the practical viability of passive site remediation by conducting laboratory and pilot-scale experiments; developing implementation technology for its deployment; investigating verification tools to assess the improvement achieved; modifying a numerical modeling code for use with gelling fluids; and upon successful completion, producing a design manual for practical application. The practical feasibility is being investigated using column and pilot-scale experiments. The column experiments are done to determine the optimal geochemical and physical conditions where passive site remediation could be employed. A cross-disciplinary pilot-scale research facility will be constructed at Drexel University for 3-dimensional modeling of passive site remediation techniques. It will be used to develop optimal methods for stabilizer delivery, and evaluate verification tools for assessing the improvement achieved. The contaminant transport code RT3D will be modified to account for variable-density, variable-viscosity gelling fluids, and subsequently used for numerical modeling. The code will be calibrated using the data from the column and pilot-scale experiments, and used to conduct predictive modeling, and eventually be used to develop design and analysis procedures. The ultimate goal of the outreach and education is to promote creativity and inspire imagination among several groups: undergraduate engineering students, the Drexel student chapter of the Society of Women Engineers (SWE), and elementary school girls from the Philadelphia area. Passive site remediation techniques could have broad application for developed sites susceptible to soil liquefaction, and to many environmental remediation problems.