Abstract
Earthquake observation is conducted at the site of a reinforced-concrete retaining wall with expanded polystyrol (EPS) backfill. The EPS was adopted since the bearing capacity of the site is not large enough for an ordinary soil embankment. The records show that the EPS backfill vibrates almost in the same mode with the ground and that the tensile force of anchor is negligibly small. A finite element analysis is also conducted and the results of the analysis agree well with the observation. Stability analysis of the retaining wall reveals that if the current stability analysis method for the ordinary gravity-type retaining walls is applied to the EPS retaining walls, the safety factors for sliding and overturning become unreasonably small.
