Numerical Simulation of Lightly Overconsolidated Clay Layers of Low Plasticity Subjected to Strong Shaking

Abstract

This study employs dynamic centrifuge testing and numerical modeling to assess the seismic response of a soft soil profile. The soil profile comprises a 23.4 m thick layer of lightly overconsolidated kaolinite clay overlying a 2.3 m dense sand layer. The centrifuge model underwent strong base shaking, and accelerations, pore pressures, and settlements were recorded at various depths. These experimental results are then compared to those obtained from a nonlinear dynamic analysis using the finite difference program FLAC. The clay layer is represented using the PM4Silt (Plasticity Model for Silt) constitutive model, calibrated based on laboratory test data. The numerical model yields reasonable predictions of accelerations at various depths, though it exhibits less nonlinearity compared to the centrifuge test. Pore pressures in the shallow clay layer match well between the physical and numerical models, but the simulation overpredicts pressures at greater depths. Despite some discrepancies between the experimental data and numerical results, the study demonstrates that numerical modeling, with appropriate calibration, can adequately replicate the seismic response of soft clay soil layers.