The research builds on previous cooperative work supported by NSF through MCEER with Japanese colleagues, supervised by Professor T.D. O'Rourke as the U.S. team leader and Professor Masanori Hamada of Waseda University as the Japanese team leader. The research program involved 27 U.S. and 38 Japanese universities, governmental agencies, utilities, and engineering and construction firms. It resulted in the publication a two case history volumes, documenting permanent ground deformation and lifeline performance during 10 US and Japanese earthquakes (Hamada and O'Rourke, 1992; O'Rourke and Hamada, 1992).

Among the most notable accomplishments of the U.S.-Japan cooperative research is the use of stereo pair air photos before and after an earthquake to perform photogrammetric analysis of large ground deformation. This process has literally revolutionized the way engineers and geologists evaluate soil displacements by providing a global view of deformation, which allows patterns of distortion to be quantified and related to geologic and topographic characteristics.

Another major accomplishment of the U.S.-Japan research has been the development of models and computer codes that provide for nonlinear material and geometric analyses of pipeline and pile foundation response to permanent ground deformation. An example of such a model is B-STRUCT, a computer program developed at Cornell that can evaluate the performance of single piles and pile groups. It has been tested successfully against pile load test data and field measurements of pile deformation caused by lateral spread during Japanese earthquakes. Model refinements have also been accomplished by means of systematic calibration and validation with centrifuge tests performed at RPI.

Research under the Mitigation of Urban Earthquake Disasters Program has involved on the US side: Cornell, RPI, and USC. Waseda University, University of Tokyo, Kyoto University, Yamaguchi University, and the Tokyo Institute of Technology have been involved on the Japanese side.

The research has developed an analytical model and design procedure for foundation piles subjected to large lateral ground deformation triggered by liquefaction. The model involves the use of p-y curves, but avoids the empiricism associated with the selection of degradation coefficients or reduction factors. To obtain a proper p-y characterization of the reaction between laterally deformed liquefied soil and an embedded pile, triaxial extension is recognized as the most appropriate analogue for the loading conditions. A suite of undrained triaxial extension tests was carried out using Nevada sand to establish the relevant strength and deformation parameters (Goh and O'Rourke, 1999). Using the material parameters obtained from these tests, 2-D finite difference analyses were performed to develop strain-softening p-y curves. Application of these p-y curves to the analyses of centrifuge experiments involving lateral spread effects on piles yields good agreement between the computed and measured responses. The strain-softening model provides excellent predictions of the measured peak and residual moments. Furthermore, the computed soil pressure diagrams agree well with the recommendations made by the Japan Road Association, which were calibrated using case histories from 1995 Kobe earthquake (Goh and O'Rourke, 2000).

The cooperative research effort involved the organization of the 7th US-Japan Workshop on Earthquake Resistant Design of Lifeline Facilities and Countermeasures Agreement Soil Liquefaction in Seattle, WA, and subsequent publication of the workshop proceedings (O'Rourke, et al., 1999). This workshop was the seventh in a series of workshops and published proceedings. Published proceedings of the workshops (Hamada and O'Rourke, 1992, 1996; O'Rourke and Hamada; 1989, 1991, 1996) provide for a state-of-the-art assessment of the technology pertaining to large ground deformation and lifelines. With over 3500 pages, the US/Japan workshop proceedings represent a substantial resource and one of the most significant collaborative efforts in geotechnical and lifeline engineering. An eighth workshop is currently being planned for Tokyo, Japan in 2002.