Lateral Movement of Pipelines on a Soft Clay Seabed: Large Deformation Finite Element Analysis

Large deformation finite element analysis using the commercial software ABAQUS has been performed to study the lateral response of pipelines on a soft seabed. Initially, pipe soil interaction simulations are presented for the case of ideal soil, with non-softening strength. Lateral resistance profiles and trajectories of the pipe during lateral motion are investigated for different initial embedment of the pipe. A more realistic soil model incorporating the effects of strain rate and strain softening is then explored. Lateral resistance profiles and trajectories of the pipes from this realistic model are compared with the ideal soil case. Finally, the concept of effective pipe embedment — which accounts for the geometric changes caused by the soil berm ahead of the pipe — is applied to both the ideal and realistic soil model responses. The normalized horizontal resistance response is shown to be linked to the effective embedment in a simple manner, regardless of the other soil and pipeline parameters. This provides a useful contribution towards the development of a general model for describing large-amplitude lateral pipe-soil interaction, taking due account of the effects of changing geometry and soil strength.