CAREER: Impact of Liquefaction-Induced Water Layers on Forward and Inverse Geoengineering Analyses

University Of Illinois At Urbana-Champaign, Urbana IL

Investigators

Abstract

The research objective of this Faculty Early Career Development (CAREER) project is evaluate water layer evolution during seismic shaking, as well as its impact on engineered structures. Ground failures related to liquefaction (e.g., lateral spreads, building settlement/tilting, floating of buried structures, flow slides) represent a significant and growing source of economic loss resulting from earthquakes. These failures damage nearly all forms of infrastructure, including lifeline and transportation facilities, building foundations, dams and levees, and waterfront structures. Understanding and mitigating these consequences is critical to maintaining resiliency following a major earthquake. However, some studies show that discrete layers of water may form within the subsurface during earthquakes, and these poorly understood ?water layers? may be responsible for a significant percentage of infrastructure damage. Therefore, it is imperative that the geo-profession answer questions such as: How and where do water layers form during earthquakes? If water layers form, how persistent and continuous are they? How do water layers influence engineering structures and our interpretation of prehistoric earthquakes? To answer these questions, an integrated field, laboratory, and centrifuge study will be undertaken to evaluate water layer evolution during seismic shaking, as well as its impact on engineered structures. The field studies will search for water layer signatures by examining numerous liquefaction sites in central and southern California and paleoliquefaction sites in the New Madrid and Wabash Valley seismic zones that are conducive to forming water layers during (or after) shaking. The laboratory and centrifuge studies will evaluate water layer formation under a wider variety of controlled conditions. The educational plan focuses on building engineering judgment in students through an ?integrated problem assessment? approach that involves fusing hands-on demonstrations (employing the laboratory equipment constructed for this project), expert-based forums, problem-based learning, cooperative learning, and creative thinking with traditional lectures and discussions. This integrated approach will better prepare students for engineering practice, where working in teams with experts from multiple disciplines to develop creative engineering solutions is commonplace. The broader impacts from this study include: (1) reducing economic losses related to earthquakes by developing tools to assess water layer formation so that proper mitigation measures can be adopted; (2) providing fundamental input to seismic hazard analysis in regions of the United States (such as the central and eastern U.S.) where paleoliquefaction studies provide the primary basis for these analyses; and (3) developing a new breed of engineers and students who blend expertise from multiple disciplines (including geotechnical engineering, earthquake engineering, engineering geology, engineering seismology, sedimentology, hydrology, and engineering mechanics) using ?engineering judgment? and ?integrated problem assessment? to address geohazards and mitigate their impacts.