Project Summary

In California, it is common practice to analyze the seismic response of levees using Newmark sliding block analysis procedures, which are intended to evaluate permanent shear deformations (DRMS, 2009). However, actual displacement mechanisms remain poorly understood and the Newmark procedure may not be an effective simplified procedure for this complex problem. This poor understanding of how to simulate levee response is rooted in unusually sparse observations of levee performance during past earthquakes. Geotechnical engineers typically work towards analysis procedures for various problems based on observed field performance during earthquakes; lacking such data we can only speculate on how to evaluate these hazards. The general objective of this project is to begin to fill this knowledge gap using levee performance data from the 2007 Niigata, Japan earthquake. Numerous levees were strongly shaken during this earthquake, and data on the performance of those levees was gathered by the jurisdictional government agencies. We propose a two-step research plan for this project. First, we propose to generate a GIS database of the Niigata study region containing levee locations, levee height, data on levee performance prior to and following the Niigata event, geologic descriptions of the surficial materials underlying the levees, and ground shaking intensity. Second, having compiled the database, we will “mine” the data to identify conditions giving rise to relatively high rates of levee damage. For example, we would expect levee deformations to increase with levee height and ground shaking level, and to have some dependence on the foundation soil condition as well. Such relationships will be quantified as a result of this research, and its products will include the database established using Google Earth and a written report. The report will provide an assessment of factors that influence damage rates in levees, typical levee deformation modes, an identification of candidate sites for more detailed, follow-up investigations in subsequent research, and the results of the interviews on emergency response and levee seismic design procedures in Japan.