Critical transportation infrastructure (e.g., buried pipelines and tunnels) may be susceptible to soil liquefaction hazards following seismic events. Liquefaction-induced uplift can significantly compromise structural stability and serviceability, requiring reliable quantification of uplift displacement for performance-based design and risk assessment. To address this need, this study presents a simplified analytical model to estimate liquefaction-induced uplift of underground structures. The model is derived from Newton’s second law of motion to establish a time-history formulation of uplift displacement. The key innovation is to explicitly connect uplift behavior to the time-dependent evolution of excess pore pressure and viscous resistance, rather than assuming a fully liquefied state with constant viscous resistance. Two models are analyzed: a constant-viscosity model and a time-dependent-viscosity model that incorporates an exponential function to describe the recovery of viscous resistance during pore pressure dissipation. This framework enables uplift displacement to be evaluated directly from pore pressure evolution, providing a more physically interpretable representation of post-liquefaction behavior. The proposed equations are validated using eight experimental cases reported in the literature, including centrifuge and shaking table tests on buried pipelines and circular underground structures, as well as an independent 1-g shaking table test conducted in this study. Results show that time-dependent viscosity is particularly important for relatively shallow and lightweight structures, while simplified constant-viscosity representations remain adequate for heavier and stiffer underground structures.
Yeh et al. (Tue,) studied this question.