Next Generation Liquefaction (NGL)
Procedures for engineering assessment of liquefaction hazards are based to a large extent on the interpretation of field performance data from sites that have or have not experienced ground failure attributable to liquefaction. However, the number of case histories supporting liquefaction procedures is remarkably small. Given the small number of most relevant case histories, it is no surprise that existing databases are incomplete, meaning they cannot constrain important components of engineering predictive models. This unfortunate situation can now be profoundly improved by order-of-magnitude increases in the size and quality of field performance data sets. The database expansion is to a large extent associated with the devastating earthquakes during 2011 in Japan and New Zealand, which caused a great deal of damage attributable to liquefaction and its effects. However, numerous other earthquakes have produced data that has not yet been considered in most of the current liquefaction triggering and effects models, including the 1999 events in Turkey and Taiwan, 2004 and 2007 events in western Japan, the 2010 event in Chile, and 2010-2011 Canterbury earthquakes in New Zealand.
The Next-Generation Liquefaction (NGL) project was launched to (1) substantially improve the quality, transparency, and accessibility of case history data related to ground failure; (2) provide a coordinated framework for supporting studies to augment case history data for conditions important for applications but poorly represented in empirical databases; and (3) provide an open, collaborative process for model development in which developer teams have access to common resources and share ideas and results during model development, so as to reduce the potential for mistakes and to mutually benefit from best practices. This approach is motivated in part by the success of the Next-Generation of Attenuation (NGA) models for ground motion prediction, which has followed this approach and has had substantial global buy-in and broad application.
The project is a collaborative effort among research organizations in nations having both substantial liquefaction risk and interested researchers with the necessary expertise. At this time, the PEER center in California is the lead organization, with partnerships with University of Canterbury Quake Center (UCQC) in New Zealand, the National Center for Research in Earthquake Engineering (NCREE) in Taiwan, and multiple agencies in Japan (Center for Urban Earthquake Engineering, CUEE; Building Research Institute, BRI; Port and Airport Research Institute, PARI; Public Works Research Institute, PWRI). The project has been overseen by a management committee including Professors Steven L. Kramer and Jonathan P. Stewart from PEER.