A series of effective stress analyses are performed on a caisson type quay wall in Kobe port, which were severely damaged during 1995 Hyogoken-nanbu earthquake. The quay wall displaced about 4~5m seaward and settled about 2m. The effective stress model used in the analyses is based on multiple mechanism model defined in strain space, which takes into account the effect of rotation of principal stress axis during cyclic loading. The model parameters for the analyses are determined by referring to the various geotechnical investigations including in-situ freezing soil sampling performed in Kobe port.
　The computed deformation of the quay wall shows about 3.5m horizontal displacement and about 1.5m settlement, which are consistent with the observed deformation after the earthquake. The analysis indicated that a half of these deformations are induced by a purely large inertia force due to the large earthquake motion and the excess porewater pressure generation in the soils behind and beneath the caisson increased the deformation to the level of those observed. A series of parametric study show that the computed deformation by the effective stress model agrees with the estimated deformation based on the case history data of caisson walls using Noda and Uwabe's empirical method.