This project is part of the NSF/USGS initiative within the National Earthquake Hazard Reduction Program (NEHRP) to investigate the effects of the Loma Prieta earthquake of 17 October 1989. It continues the research that was initiated the day following the Loma Prieta earthquake, namely to collect the perishable data on the seismic performance of soil nailed walls in the San Francisco Bay area. Soil nailing is a construction procedure used to shore vertical soil cuts for temporary or permanent purposes. Soil nailing differs from conventional soldier pile and tie-back shoring systems in many ways. The technique was first used in California in the San Francisco area, where numerous temporary and permanent walls have been constructed in the past 5 to 6 years. The major concern in California with soil nailed walls is their performance during earthquakes. The main objective of this follow-on project is to analyze the data collected so as to obtain a better understanding of the behavior of soil nailed walls when subjected to seismic forces. Data collected following the earthquake are being compared with the pre- earthquake data to determine the changes in the wall and soil movements, and in the nail resistance. The performance is being evaluated with respect to soil conditions, wall geometry and construction, and ground motions.
