Seismic Remediation of Seawall by Engineered Geomaterial

Abstract

In response to severe damages that occurred due to the recent earthquakes in Japan, a strategy was adopted to increase the seismic resistance of the retaining structures in the port areas using an engineered geomaterial. The engineered geomaterial is comprised of the dredged material obtained from the seabed close to the project site, air foam to control the density, and portland cement to fill the voids and glue the soil particles together. The idea is to reduce the lateral pressure behind the damaged retaining structures and to reduce the risk of liquefaction by using a nonliquefiable material. The objective of this paper is to present the use of an engineered geomaterial to reconstruct a damaged caisson-type seawall project that moved 0.8 to 3.8 m in the horizontal direction and settled 1.1 to 2.5 m due to the Kobe earthquake. The engineering properties of the engineered geomaterial are monitored and reported up to 10 months after the construction. Relationships are developed to correlate various laboratory and field tests related to the engineered geomaterial. The restoration strategy adopted for this project represents an effective use of low quality dredged soil for construction purposes in the port and coastal areas.