9315694 Nazmy This research project addresses the reinforcement of soil excavations to resist earthquake shaking through the use of soil nailing. Soil nailing is an insitu soil reinforcement technique that has been tested and implemented during the past twenty years in a variety of civil engineering applications. The fundamental concept consists of placing in the ground passive inclusions (steel reinforcing bars) as the excavation proceeds, in order to restrain displacements, limit decompression during and after the excavation, and to form a nailed mass that can behave similarly to a soft retaining wall. Post-earthquake field investigations and laboratory studies have shown that soil-nailed structures are highly resistant to earthquake loading. However, to date, only limited studies have been conducted to evaluate their response and possible failure mechanisms under seismic loading. Such research is needed to develop reliable design methodologies. Given the increasing popularity of soil nailing, this research project will have considerable impact on the geotechnical design and construction industries. This project involves numerical analyses, laboratory experiments -- in which a geotechnical centrifuge is used to subject small-scale models to horizontal shaking -- and post earthquake observations. This integrated approach provides a thorough understanding of the seismic response of soil nailed systems, and will result in specific engineering guidelines for their seismic design. This is a collaborative project involving the University of California at Los Angeles and the Polytechnic University, New York, with the experiments being performed on the geotechnical centrifuge at Rensselaer Polytechnic Institute.