The Uplift Resistance of an Offshore Pipeline and the Effect of Soil Homogeneity

Offshore pipelines are often considered one of the most reliable fluidized fuel transportation systems. However, the transporting fuel with enhanced temperature induces thermal stress in the pipeline, which further threatens to buckle and rupture the offshore pipelines. In the current study, the buckling resistance behaviour of an offshore pipeline is studied using a finite element package (PLAXIS 2D). Furthermore, a comparison of uplift resistances for the homogeneous and normally consolidated (NC) soil beds is performed to understand the effect of soil homogeneity. The numerical model is validated with the past studies, and a good match is obtained. Moreover, different soil and installation parameters are varied to perform a parametric study and investigate the pipeline uplift resistance behaviour. Two different buckling resistance (Pu) behaviours of the pipeline are obtained in pre-peak and post-peak conditions for both homogeneous and NC soil bed conditions. The magnitudes of Pu for homogeneous and NC soil conditions are compared, and the changes in Pu are reported and justified. The variation of the Pu with different parameters (soil unit weight and embedment depth ratio) is also described using the failure mechanism of the soil around the pipeline.