Numerical Evaluation of a Bottom Plate Countermeasure Against Pipeline Uplift in Liquefiable Ground

Pipelines buried in liquefiable ground are vulnerable to uplift, which can cause serious damage. Various countermeasures have been proposed to mitigate pipeline uplift, some of which have adverse effects. Prior centrifuge model tests have shown that a bottom plate countermeasure (BPC), in which a horizontal plate is installed beneath the pipe, effectively suppresses uplift. In this study, finite element method analyses were performed to examine the behavior of the surrounding soil under BPC application and to evaluate the effects of plate length, burial depth, ground conditions, and input acceleration. The analyses showed that the BPC enlarged the soil region resisting pipeline uplift by extending the shear surface deeper into the horizontal plate and farther outward from the pipe. Because of this resistance mechanism, the BPC was particularly effective under shallow burial conditions, where reduced overburden load made pipelines more susceptible to uplift. Analyses considering field pipeline installation practices, with the pipeline embedded in a sand-backfilled trench within non-liquefiable native ground, also showed that uplift with the BPC was limited to approximately 1 mm or less, demonstrating strong uplift suppression. These results confirm the applicability of the BPC and provide a basis for future field implementation.