Study of Liquefaction Damages of Quay-Walls and Breakwaters During Kobe Earthquake

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Tanaka, Yasuo; Yagiura, Y.; Shimokawa, K.; Higashi, S.; Kishida, T.; Mizuwake, N.
University of Missouri--Rolla
Geotechnical Engineering
conference paper description
During Kobe Earthquake, very extensive damages of harbor facilities such as quay-wall and breakwater occurred in Kobe Port and also along the coastal areas between Kobe and Osaka cities. Major causes of the damages were the liquefaction of sands underlying and behind the concrete caisson and also strong earthquake shaking force on the caisson. The degree of damage varied considerably depending on location and also on the size of structure. In order to understand the mechanism of damage as well as the factors that controlled the degree of damage, it was necessary to examine and analyze the case records of damages of these structures. This paper describes the result of such study on liquefaction damage of quay-walls and breakwaters. Through the study, it was found that the movement of sand at shallow depth below the caisson base is mainly responsible for a large settlement of caisson, but the mode of deformation is different between quay wall and breakwater. Also an effective stress liquefaction analysis was performed on the damaged quay-walls and breakwaters in order to check the applicability of effective stress liquefaction analysis on damage assessment. It was found that the effective stress analysis may be used to establish the overall trend of damage variation with the intensity of seismic motion, but problems exist in setting the dynamic parameters for the analysis, such as damping parameters, in order to obtain a reliable result.