Large Deformation Analysis of Lateral Pipeline-Backfill-Trench Interaction by Remeshing and Interpolation Technique with Small Strain Model (RITSS)-Paper

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The study develops a two-dimensional large-deformation finite-element framework using the remeshing and interpolation technique with small strain (RITSS) to examine lateral pipeline movement. It investigates both interaction among a pipeline, trench backfill and native seabed, and the effects of pore-pressure generation and consolidation in clay. The models were compared with published centrifuge tests.<br /><br />For trenched pipelines, the model reproduced measured force–displacement responses more closely than several conventional theoretical solutions, particularly as the pipe moved from weaker backfill into stronger native soil. Simulations showed evolving shear bands, ground heave and settlement; failure patterns varied with burial depth. The results demonstrate that trench geometry and backfill properties can substantially alter soil deformation and lateral resistance.<br /><br />The coupled consolidation framework predicts excess pore pressures around a moving pipe, including negative pressures (suction) behind it. These pressures influence failure mechanisms and mobilized resistance. Its predictions generally agreed with centrifuge data and established guideline curves, though resistance was somewhat overpredicted in the consolidation comparisons. Differences between normalized resistance results also indicate that backfill and trench effects can reduce ultimate resistance relative to a uniform-soil case.<br /><br />Overall, the RITSS-based approach provides a useful tool for modeling large pipeline displacements and progressive soil failure, while accounting for trench effects and drainage behavior that simplified design methods may overlook.

Keywords

pipeline lateral movement

large-deformation finite element

RITSS

trench backfill

native seabed

pore pressure generation

clay consolidation

centrifuge tests

soil resistance

shear bands