Assessment of Seismic Displacement of Quay Walls

Abstract

Quay walls are the important retaining structures offshore used to retain the port facilities on one side and seawater on the other side. Their safety and desired level of performance is most essential for the social and economic growth of a country. It is extremely important that they perform well in all environments and under all forces. Any damage to such structures can result in serious problems to the functioning of ports creating enormous economic loss and inconvenience. The performance of quay walls during earthquakes is under serious scrutiny as they have failed miserably under seismic loading all over the globe, with no exception under Indian conditions (Gujarat earthquake, 2001, Andaman Islands during Sumatra Earthquake, 2004). Performance-based design is gaining considerable importance in the design of geotechnical structures such as foundations, embankments, slopes, and retaining walls, especially under extraordinary loading conditions such as earthquakes. It is rational to consider displacement or deformation as one of the criteria in addition to force-based concept in the seismic design of these structures with no exception to quay walls. Considering these aspects, this paper attempts to present the seismic performance of quay wall system using GEOSTUDIO with emphasis on the permanent horizontal displacement of quay wall. For this purpose, a typical quay wall system comprising of foundation soil, backfill soil, and the quay wall is analyzed in a 2D plane strain environment subjected to varying levels of earthquake motion. The effects of varying properties of backfill and foundation soils on the performance of quay wall are highlighted. The study also includes the consideration of liquefying backfill on the displacement of quay wall. It has been observed that liquefaction of backfill soil is the major culprit for the large displacement of quay wall towards the sea during an earthquake. The study can help in the progress towards performance-based design of geotechnical structures under earthquake loading.