Effect of Soil Spring Pipe–Soil Interaction Behavior on the Mechanical Response of Pipe under Soil Displacement

The soil spring pipe–soil interaction (SSPSI) model is crucial for quantifying the relationship between permanent ground deformation and the forces acting on buried pipelines. The accuracy of this model directly influences the reliability of the pipeline’s mechanical response. The most common approach to modeling SSPSI involves determining soil spring stiffness using the American Lifelines Alliance (ALA) guidelines and then analyzing pipeline deformation. However, the axial soil resistance values provided by the ALA are often underestimated, and they fail to account for resistance softening behavior. Additionally, the lateral soil resistance does not reflect the uneven distribution around the pipe’s circumference, leading to discrepancies between the model’s predictions and real-world pipeline behavior. To overcome these limitations, this paper introduces a three-dimensional mechanical response model for buried pipelines based on an improved SSPSI framework. The study investigates the influence of variations in ultimate soil resistance, resistance-softening effects, and circumferential nonuniformity on pipeline mechanical responses. Specifically, it evaluates the impacts of these factors on pipeline bearing capacity under four commonly adopted failure criteria. The findings indicate that lateral nonuniform soil springs are particularly critical for accurately capturing pipeline responses, including deformation, displacement, strain, and displacement-resisting capacity. In contrast, omitting axial soil spring softening does not substantially affect the practical engineering prediction of pipeline mechanical responses, provided the ultimate axial soil resistance values are accurately determined. These insights offer important guidance for the effective design and evaluation of oil and gas pipelines.