Development of numerical model of wrap-faced walls subjected to seismic excitation

Abstract

ABSTRACT: Reinforced-soil walls offer an excellent solution to many problems associated with earth-retaining structures, especially under seismic conditions. This paper presents the seismic response of wrap-faced reinforced soil-retaining walls through numerical models. The development of numerical models for simulating shaking-table tests on wrap-faced, reinforced soil-retaining walls, and their application in investigating the seismic response of physical wall models, are presented. Numerical models of the wrap-faced reinforced-soil walls are simulated using the program FLAC3D. The soil is modelled as an elasto-plastic Mohr–Coulomb material, coded with stress-dependent hyperbolic soil modulus parameters. The shear behaviour of granular soils under cyclic loading is modelled using a non-linear and hysteretic constitutive relation that follows the Massing rule. The reinforcement is modelled as a geogrid shell structural element. Various interfaces are also considered for proper interaction between dissimilar elements. The results obtained from the numerical simulations are validated with those of experimental studies reported in the literature. The horizontal and vertical displacements and octahedral shear strains are determined along the length of the backfill to study the location of failure surfaces within it. It is observed that the deformation of a wrap-faced wall subjected to dynamic excitation consists of three different modes of failure: shear deformation within the reinforced zone, relative compaction near the end of the reinforcement, and a compound failure surface extending to the backfill zone. The position of the compound failure surface within the retained zone depends on the excitation levels. The effects of the length of reinforcement on the failure modes are also studied.