Effective-stress seismic analysis of a gravity multi-block quay wall

The seismic performance of an existing gravity quay wall consisting of concrete blocks is investigated using effective stress analysis. The study focuses on the effect of the uncertainty associated with the spatial variability of the material properties in the foundation and backfill zones on the horizontal displacements, settlements and rotations of the wall as well as of porewater pressure behind the wall. A modification of the comprehensive generalized plasticity Pastor-Zienkiewicz constitutive model is used for modelling the cyclic behavior of the sandy gravel and rockfill. Four different numerical models are considered in an extensive parametric study consisting of 180 analyses. The results show that, for constant average relative density, the effects of its spatial variability are smaller than the effects of the frequency characteristics of the earthquake excitation. Moreover, it is shown that a foundation of high relative density may decrease significantly settlements and rotation of the wall, but some reduced horizontal displacements caused partly by block-to-block sliding may still take place. Excess porewater pressures immediately behind the wall are mostly negative, increasing the soil resistance.