Seismic behaviour of U-shaped retaining walls in non-liquefiable and liquefiable soils

This paper investigates the seismic performance of U-shaped retaining walls under seismic loading in liquefiable and non-liquefiable soils. Two-dimensional nonlinear finite element models are developed in PLAXIS 2D software. The behaviour of the dry sand soil in the model is simulated using the Hardening Soil Model with Small Stiffness (HSsmall) material model, which can represent the nonlinear behaviour and increased stiffness at small strains of soils and is validated against experimental data. Meanwhile, the UBC3D-PLM material model simulates the liquefiable sand behaviour under seismic loading. The numerical model is employed to investigate the effect of relevant design parameters on the retaining wall seismic response. The effects of wall flexibility, soil strength, stiffness, earthquake frequency content, and peak ground acceleration on the seismic response of the U-shaped retaining wall and both liquefiable and non-liquefiable sandy soils are investigated. Key findings indicate that wall flexibility and soil conditions strongly influence seismic wall deflections and earth pressures, with liquefiable soils showing more notable changes in seismic lateral pressures. Additionally, low-frequency seismic motions significantly impact seismic pressures, mainly through variations in energy dissipation. • Soil liquefaction reduces surface acceleration across soil layers in the presence of retaining walls. • Seismic flexural wall response increases in loose sand compared to dense sand due to soil relative density. • Wall rigidity affects deflections in non-liquefiable soils and seismic pressures in liquefiable soils. • Low-frequency earthquakes cause higher seismic pressures due to reduced damping.