ABSTRACT

The dynamic response of gravity type of quay wall was analyzed by means of Finite Element Method (FEM) with a focus on the inter action between caisson and backfill ground. First, the fundamental vibration property of the quay wall is examined, and the FEM model is calibrated, so as to simulate the observed behavior in a micro tremor measurement. Next, the behavior of earth pressure on caisson from backfill ground in the course of liquefaction is analyzed, and the significant effect of liquefaction on the stability of quay wall is indicated through the comparative examination of the analytical results.

INTRODUCTION

The port and harbor facilities such as gravity type quay wall have been frequently and severely damaged in the destructive earthquakes. This type of damage is associated with the liquefaction and flow failure of the backfill ground of caissons (e.g., JGS, 1994; Inagaki, et al., 1996; Kamon, et al., 1996). On the other hand, the quay walls whose backfill ground had been treated and not been liquefied, could have survived the sever shakes in earthquakes (JGS, 1994; Hokkaido Development Bureau, 1996). This trend implies that the earth pressure the caisson is subjected to is different depending on the occurrence of the liquefaction. The authors conducted some series of shaking table tests on model quay walls focusing on the effects of liquefaction in the backfill ground; Kohama et al., 1998a, 1998b: Miura et al., 2000. They found the significance of the occurrence of liquefaction in backfill ground. The movement of the caisson was found to be quite different depending on whether liquefaction occurred in the backfill ground or not. The fluctuating earth pressure on the caisson back suppressed the movement of the caisson when liquefaction did not occur and the backfill ground retained a certain level of stiffness.

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