An Experimental and Numerical Study of Prefabricated Vertical Drains as a Liquefaction Countermeasure for Mat-Founded Structures

Centrifuge experiments and parallel nonlinear numerical simulations were conducted to investigate the seismic response of potentially inelastic, multi-degree-of-freedom structures on layered, liquefiable soil deposits and the effectiveness of mitigation with prefabricated vertical drains (PVDs). Fully-coupled, 3D, nonlinear numerical simulations of the soil-foundation-structure system in centrifuge were performed in the finite element platform OpenSEES. Experimental results showed that PVDs can effectively speed up pore pressure dissipation after shaking and reduce building's settlement and tilt potential. PVD were, however, shown to increase roof accelerations, displacements, and drift ratios, which need to be considered in design. Although the numerical results showed some discrepancies in capturing the dissipation rate of excess pore pressure and foundation's residual tilt, they generally captured its settlement, particularly for thinner liquefiable layers. Future improvements are needed in the numerical models to better capture the rate of dissipation, volumetric strains due to sedimentation, and the localized deformations responsible for foundation's cumulative rotation over time.