Numerical Study of Liquefaction-Induced Uplift of Underground Structure

Abstract

A finite-difference modeling was performed to investigate the liquefaction-induced uplift of an underground structure. The liquefaction-induced uplift of a 5 m diameter underground structure buried at a depth of 5.5 m was analyzed. The soil was modeled using the elastic-perfectly plastic Mohr–Coulomb model by incorporating the Finn–Byrne pore-pressure formulation. The pore pressure and uplift response of the underground structure obtained using sinusoidal input motion were validated by comparing centrifuge tests and numerical analysis results reported in the literature. The responses obtained using a scaled-up 2015 Nepal-Gorkha earthquake accelerogram and equivalent sinusoidal motion were compared and were found to be similar. Further parametric analysis was carried out to study the effect of the characteristics of the input motion on the uplift of the structure. The numerical results revealed that the primary reason for the uplift of the underground structure was the generation of pore pressure at the invert of the structure. It also was found that significant liquefaction-induced uplift displacement of the underground structure occurred for input motion with a peak input acceleration more than 0.22g and a frequency less than 0.75 Hz.