[Truncated abstract] This thesis described research into the pipe-soil interaction forces during large movements of deep-water pipelines, using numerical methods. Vertical penetration, lateral break-out and steady-state lateral resistances were investigated with the help of numerical models using a large deformation approach implemented within the ABAQUS finite element software and sophisticated soil constitutive models. The large deformation finite element methodology is based on a periodic remeshing and interpolation technique which was developed for this research to incorporate the effects of changes in the strength and geometry of the seabed during large movements of the pipelines. Soil constitutive model that accounts for strain rate effects and remoulding were implemented to simulate realistic behaviour. Coupled pore-fluid stress analyses were also carried out using the modified Cam Clay plasticity model to investigate the effects of drainage and consolidation on interaction forces. The initial vertical penetration of a seabed pipeline is an important parameter for design of these pipes against lateral buckling and other design conditions. The penetration rate and strain softening have marked effects on the resistance experienced during vertical penetration. A simple elastic perfectly plastic soil constitutive model was modified to incorporate these effects to identify the equivalent shear strength of the soil. A parametric study considering wide range of parameters was conducted and the results were unified when the vertical penetration resistance was normalised using this equivalent shear strength. Simplified equations are presented for ease of application. Lateral pipe-soil interactions were also studied to observe the effects of the initial embedment and different pipe weights.
|Qualification||Doctor of Philosophy|
|Publication status||Unpublished - 2012|