SEISMIC RESPONSE OF STEPPED RETAINING WALL

Abstract

Retaining structures are widely implemented civil engineering structures utilized to retain backfill soil material. The assessment of lateral thrust plays a notable role in proper selection and design of earth retaining structures. Prior research studies have documented various modes of failure experienced by conventional retaining walls, subjected to different loading scenarios. The implication of seismic loading tends to induce additional lateral thrust and hence due consideration of such elevated thrust needs to be accounted in order to safeguard these structures from catastrophic failures. This present study focuses on the stability evaluation of a novel type earth retaining structure i.e., stepped retaining wall, under active condition subjected to static as well as seismic loading. This study comprises of active force assessment on an inclined wall with the implementation of force polygon method. The critical angle of the failure surface was obtained corresponding to the case of maximum active force acting on the inclined wall. The horizontal coefficient of active earth thrust i.e., ka, obtained through the force polygon method has been validated with the Coulomb's active lateral earth pressure coefficient. Further, the active lateral thrust at various heights along the wall as well as total active force deduced using Coulomb's computation has been validated with the help of Finite Element Modelling using ABAQUS software. Parametric study has also been carried out to evaluate the Factor of Safety (FOS) against sliding and overturning conditions for stepped wall having heights of 10m and 15m respectively by varying the friction angle of backfill soil as well as interface friction between soil and wall. Idealization of stepped wall has been accomplished by considering three different simplified models with the help of numerical modelling. The horizontal force obtained from both numerical as well as analytical studies pertaining to the idealized models were compared with the results of finite element modelling of stepped wall. Parametric investigations have also been accomplished in this study by varying the backfill soil friction angle (Φ), interface friction between soil and wall (δ), height of water table in the backfill soil.