Computation of sliding displacements of seawalls under earthquake conditions

To understand the serviceability aspects of seawalls, it is essential to study the permanent displacements of seawalls that occur during the earthquakes. Studies in the existing literature have concentrated on displacements of retaining walls with dry backfills; to the authors’ observation there is no specific analytical investigation devoted to the earthquake-induced displacements of retaining walls with submerged backfills. This paper focuses on sliding displacements of gravity type seawall retaining a submerged backfill under active earth pressure condition during the earthquakes. The threshold seismic acceleration coefficients required for initiation of sliding and the amount of sliding displacement due to seismic loading are calculated by adopting Newmark’s sliding block method. One of the prime features of the study is the estimation of seismic inertia forces in the submerged soil and wall applying the modified pseudo-dynamic method. The comparison of the results obtained using the proposed analytical formulation with the existing literature found to be in good agreement. A comprehensive parametric study has been conducted to understand the effects of different parameters such as seismic horizontal and vertical acceleration coefficients, soil and wall friction angles, width of the wall, wall inclination and excess pore water pressure ratio.