Analysis and design of EPS-geofoam embankments for seismic loading

The use of block-molded expanded polystyrene (EPS-block) geofoam as a lightweight-fill material for highway embankments is a relatively mature geotechnology with more than 30 years history of successful application worldwide. Basic analysis and design procedures are now well established and documented, and current research and development efforts are focused on making incremental improvements. One such area of improvement relates to analysis and design for seismic loading. The recent construction of several EPS-geofoam highway embankments on the Central Artery/Tunnel (CA/T) Project in Boston, well known as the 'Big Dig', resulted in an opportunity to advance the state of practice for EPSgeofoarn embankments subjected to seismic loading. In particular, a newly recognized behavioral mode referred to as seismic rocking was identified and found to govern the design of these fills for internal stability. This behavioral mode is described in this paper in the context of summarizing the current state of knowledge with respect to seismic analysis and design of EPS embankments.