Seismic Analysis of Retaining Wall Subjected to Surcharge: A Modified Pseudodynamic Approach

Abstract

The rise in failure of retaining walls subjected to dynamic loads is of increasing concern in earthquake-prone areas. The purpose of this study is to establish a closed-form solution for seismic active thrust and its distribution on a retaining wall subjected to surcharge stresses. The proposed method considers dynamic properties of the backfill soil to capture more realistic behavior. An upward propagating SH wave obeys boundary constraints, owing to surcharge acting on the surface of the backfill. Both the incident wave and the wave reflected from the surface of the backfill are considered in the analysis. An amplified SH wave is considered to estimate both inertial force due to surcharge and inertial force due to retained soil mass. Results obtained from limit equilibrium analysis are compared with those obtained by performing numerical analysis using finite-element modeling. It is observed that the frequency of the seismic wave plays an important role in estimating the seismic coefficient of earth pressure for different surcharge magnitudes. The study reveals that though the amplification of the wave is not much affected by the magnitude of the surcharge, consideration of the amplified wave when estimating the inertial force due to surcharge influences the total seismic active thrust. Obtained results are in good agreement with the well-established pseudostatic method. An attempt is made to study the effect of strain-dependent dynamic soil properties on seismic lateral coefficient for varying surcharge coefficients. This study definitively answers the question regarding the behavior of retaining wall with surcharge subjected to seismic loading that considers wave propagation.