Effects of density of geofoam cushion on seismic performance of the retaining wall: Experimental study

In recent years, three important factors have been taken into account in designing safe and useful retaining walls in seismically active regions: cost, environment and earthquake performance. One of the improvement methods defined in the literature is the inclusion of the lightweight, compressible cushion layer behind the retaining wall. The lightweight materials as tire waste-sand mixtures and EPS Geofoam have various advantages such as low unit weight, low bulk density, and high vibration absorption capacity. EPS Geofoam has recently been proposed as a seismic cushion, which is an energy absorption layer due to the higher damping properties of lightweight materials depending on their density compared to the sand. This study covers the evaluation of the shaking table experiments performed on a 1/25 scaled wall model in the rigid-sided plexiglass soil box. This study aims to determine the effects of geofoam density on the seismic performance of the retaining wall with the cushion under real earthquake motion. Shaking table test results of the retaining wall with cushion are compared with the uncushioned case. Test results revealed that the cushion density has an important effect on improving the seismic performance of the wall.