Effect of Touchdown Trench Modelling on SCR Fatigue Life

2018 5th International Conference on Coastal and Ocean Engineering

Hu, G.^1 ; Shi, C.^2 ; Zhao, Y.^2

Dalian Maritime University, Dalian, China^1

School of Petroleum Engineering, China University of Petroleum, Qingdao, China^2

关键词: Analytical equations;    Equilibrium conditions;    Industry practices;    Soil stiffness;    Steel catenary risers;    Survey data;    Touch Down Zone;    Touch-down zones;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/171/1/012020/pdf
DOI  :  10.1088/1755-1315/171/1/012020

来源: IOP

【 摘 要 】

Touchdown zone (TDZ) is one of the most critical fatigue hot spot for a Steel Catenary Riser (SCR). In current industry practice, a flat profile is always used when modelling the seabed surface. However, survey data shows that trenches are formed at SCR touch down zone after riser installation. It is important to understand the impact of trench modelling for fatigue life at TDZ. This paper presents a SCR TDZ fatigue life comparison between a flat and trenched seabed profile using Finite Element Analysis (FEA) models based on linear soil stiffness. The trenched seabed is modelled in its assumed equilibrium condition using an analytical equation derived from non-linear hysteretic analysis in the literature. Further analyses are conducted for more parameters. The objective of this study is to determine if a linear seabed model with trenched profile can improve TDZ fatigue life of an SCR when compared to an SCR on a flat seabed surface.