Seismic response of lightly over-consolidated clay layers: Centrifuge experiments and numerical simulations

This study integrates centrifuge experiments and advanced numerical simulations to investigate the seismic response of lightly over-consolidated, low-plasticity clay layers, with a focus on evaluating the predictive capabilities of available numerical tools under various seismic scenarios. Centrifuge model tests were conducted on a deep clay profile reinforced with soil-cement (SC) grids and subjected to multiple shaking events, including scaled long-period and high-frequency real ground motions. A two-dimensional nonlinear dynamic analysis (NDA) using FLAC2D with PM4Silt and PM4Sand constitutive models is calibrated against experimental measurements. A detailed parametric study explores how variations in ground motion intensity and frequency content influence soil nonlinearity and excess pore pressure generation, providing insights into the dynamic behavior of soil under various shaking scenarios. Sensitivity analyses on undrained shear strength, damping ratio, and permeability highlights the dominant influence of shear strength on the response of cohesive soils. DEEPSOIL simulations match experimental results under moderate shaking but show limitations in capturing nonlinear effects under intense shaking. The findings emphasize the importance of advanced constitutive models for evaluating nonlinear seismic site response in cohesive soils and provide recommendations for geotechnical engineering practice.