The Effect of EPS Geofoam Thickness on the Seismic Performance of Quay Walls

Abstract

Water front engineering structures have experienced earthquake induced damages from minor to catastrophic scales during the past few decades. Previous major earthquakes including the 1995 Kobe earthquake, the 1999 Kocaeli earthquake and the 2011 Tohoku earthquake showed that ports and all of its structural components are exposed to a great seismic risk. Thus, great attention should be paid by means of seismic performance in the design phase of such facilities. EPS geofoam inclusion as one of the several improvement methods can increase the seismic performance of the quay walls. It is a well-known method to reduce the magnitude of earthquake-induced dynamic forces against rigid earth retaining wall structures. The aim of this numerical study is to determine the effects of using different thicknesses of EPS geofoam cushion on the seismic performance of quay walls. Non-linear dynamic analyses were performed using the PLAXIS software. During the analyses, real earthquake records were used. Evaluation of the results reveal that inclusion of EPS geofoam as a seismic buffer decreases earthquake-induced dynamic forces against the rigid quay wall model successfully in comparison of the nominally identical structure with no compressible cushion layer. Increasing cushion thickness was found to have a positive effect on the selected performance indicators. More importantly transmitted peak accelerations within the quay wall model are reduced up to 84%. One limitation of using lightweight-compressible materials behind rigid walls may be the possibility of increased displacements and rotations which should be controlled carefully.