Seismic Rotational Stability of Waterfront Retaining Wall Using Pseudodynamic Method

Abstract

Design of waterfront retaining walls under seismic conditions is an important topic of research among the geotechnical engineering fraternity, and recently there have been studies in which the stability of rigid waterfront retaining walls has been assessed. However, an important aspect of seismic rotational stability of such walls is still missing from the literature archives. The present study shows the importance of rotational displacements for the design of the rigid waterfront retaining wall. Consideration has been made for the calculation of the hydrodynamic pressure as well as the seismic forces, both due to the seismic pressure and seismic wall inertia. These seismic forces have been calculated using the pseudodynamic approach. The free water condition has been considered in the analysis, and thus the hydrodynamic pressure has been considered to exist on the downstream face of the retaining wall as well, and a well-known expression approximating the effect of the inertia of the water due to the earthquake has been used for the estimation of this hydrodynamic pressure force. Simple expressions for the calculation of rotational displacement both during and after the earthquake have been proposed, and typical results have been obtained. It is observed that with an increase in the ratio of the water level to the total height of the wall from 0.50 to 1.00 the rotational displacement of the wall increases by about 110%. Similar trend of an increase in the value of the rotational displacement was observed for an increase in the values of the horizontal and vertical seismic acceleration coefficients. Also, the parametric study carried out in the analysis suggested that the rotational displacement is sensitive to other parameters such as the upstream water height, pore pressure ratio, soil, and wall friction angles. Due to nonavailability of the results in which rotational stability of the waterfront retaining wall under the seismic conditions has been studied, the results from the present analysis seem to bring out a unique approach.