Performance evaluation of PM4Sand model for simulation of the liquefaction remedial measures for embankment

Abstract

Non-linear seismic deformation analyses of an earth embankment founded on liquefiable soil were performed using the FLAC 2D and PM4Sand as the constitutive model to simulate the seismic behaviour of loose sand foundation. PM4Sand model was calibrated to the cyclic behaviour of Nevada 120 sand. The untreated embankment-foundation system was subjected to three sinusoidal shaking events. Though the computed deformations are in reasonable agreement with measured results, the excess pore pressures (EPP) in the central foundation region were found to be overpredicted. The temporal variation of sand permeability was considered for the simulation of untreated sand deposit supporting the embankment. The low effective stresses computed to be regained following the dissipation of EPP for the case with variable sand permeability implies that the numerical model is not capable of accounting the shear-induced dilation in the foundation soil underlying the embankment. So, the class-C1 simulations were performed to evaluate the numerical model by adjusting the dilation parameters in the model. Following this, the three different liquefaction mitigation measures such as dense sand columns within the foundation soil, gravel berms along the side slopes of the embankment, and vertical sheet piles below the embankment toes were simulated and comparisons with experimental data are reported.