Numerical investigation of seabed response around submarine buried pipelines considering spatially heterogeneous seabed properties

Submarine pipelines are critical infrastructure for transporting oil and gas resources in marine engineering. Wave-induced pressure can generate oscillatory and residual pore pressure responses within the seabed, potentially leading to seabed liquefaction and threatening pipeline stability. Existing numerical models, often based on homogeneous or layered-homogeneous assumptions, typically solve oscillatory and residual responses separately. This approach not only neglects their coupled effects but also fails to adequately account for seabed spatial heterogeneity. This study establishes a fully dynamic coupled model for wave-pipeline-seabed interaction, which explicitly accounts for spatial heterogeneity of seabed parameters and the feedback mechanism of pore pressure accumulation. The proposed model is applied to investigate the response of buried pipelines across varying soil properties, revealing the critical influence of pipeline embedment depth ratio and seabed particle size on seabed liquefaction patterns. The pipeline’s impact on pore pressure is found to be most pronounced at moderate embedment depths. Furthermore, a pivotal shift in the governing mechanism is identified with particle size: the pipeline suppresses oscillatory pressure in coarse-grained seabeds, whereas it markedly amplifies residual pressure accumulation in fine-grained seabeds. The study also reveals that the soil property differences between the trench backfill zone and the undisturbed zone, formed by engineering disturbances, significantly affect soil stability around the pipeline. While trench heterogeneity generally has a limited effect on the liquefaction depth, it significantly reduces the spatial extent of the liquefied zone.