Effect of Pipeline Burial Depth on Damage Response of Subsea Pipelines Under Anchor Interaction in Soft Clay Seabed

Subsea pipelines are vulnerable to anchor-induced structural damage during ship mooring operations, particularly from raising and dragging interactions.This study quantified the effects of the pipeline burial depth on the structural damage response under these two loading scenarios in a soft clay seabed.Three-dimensional finite element analyses were conducted using Abaqus/Explicit with the Coupled Eulerian-Lagrangian method, simulating a 6-ton stockless anchor on a soft clay seabed modeled using the Mohr-Coulomb constitutive model.Half-buried (1/2D, Case 1) and unburied (Case 2) conditions were compared using the equivalent plastic strain (PEEQ), von Mises stress, contact characteristics, and energy dissipation as primary damage indicators.In the raising scenario, both pipelines remained within the elastic regime (PEEQ = 0), but the unburied pipeline showed 44% higher von Mises stress, 58.7% greater lateral displacement, and 32% larger resulting displacement compared to the half-buried case.For the dragging scenario, the unburied pipeline showed 4.9 and 2.97 times higher PEEQ and peak contact pressure, respectively, while the half-buried pipeline exhibited 6.7 times more contact nodes and 61% higher plastic dissipation energy.These findings show that pipeline burial provides consistent protection under anchor dragging and raising conditions, underscoring the need for scenario-specific burial design standards.