Fully Coupled Effective Stress Analysis of Pipeline Response Considering Dynamic Permeability during Liquefaction

Liquefaction-induced ground failure poses severe risks to the structural integrity of buried lifelines. While pipeline behavior in liquefiable soils has been widely studied, current design guidelines often overlook the complex hydromechanical coupling, specifically local flow and permeability variations, during earthquake loading. This study addresses this gap by implementing a specific state-dependent permeability algorithm (via FISH) within a two-dimensional fully coupled effective stress framework using the PM4Sand constitutive model. Unlike conventional undrained analyses, this approach captures the transient variation in hydraulic conductivity during excess pore-water pressure generation. Results demonstrate that neglecting these dynamic permeability effects can lead to an underestimation of pipeline uplift by up to 30%, significantly increasing the risk of upheaval buckling. Furthermore, the analysis investigates critical design parameters, including the pipeline material, internal operating pressure, relative density, and ground motion characteristics (near-field versus far-field). The findings indicate that internal pressure plays a significant role in stability and that current design protocols may require adjusted safety factors to ensure asset resilience against liquefaction-induced buoyancy.