Bidisperse submerged landslides impacting pipelines over an erodible seabed

The increasing development of deep-sea resources and the installation of subsea pipelines have raised significant concerns regarding submarine landslides, which pose substantial threats to pipeline integrity. In erodible seabed environments, the dynamic behavior of landslides is governed by complex interactions among multi-component particles, and their impact mechanisms on pipelines remain poorly understood. Therefore, accurately assessing the impact of landslides on pipelines in such conditions is of great importance for ensuring the safety of deep-sea pipelines. To address this issue, a coupled CFD-DEM (computational fluid dynamics-discrete element method) simulation framework is developed, integrating fluid flow, multi-component landslide particles, and erodible seabed. The model is validated using classical benchmark cases, and the impact processes of landslides on the pipelines are systematically investigated. Results indicate that seabed permeability, landslide particle size, pipeline position, and the particle composition of both the landslide body and the seabed significantly influence impact behavior. The interactions between polydisperse granular systems and erodible seabed produce impact characteristics that differ markedly from those observed on rigid seabed. This study provides a theoretical basis for evaluating the risks of submarine landslides' impact on pipelines and offers practical guidance for disaster prevention and engineering design.