0
Research Papers: Offshore Geotechnics

Seabed Interaction Modeling Effects on the Global Response of Catenary Pipeline: A Case Study

[+] Author and Article Information
Hany Elosta

Technip Norge AS,
P.O. Box 603 Kjørboveien 14 & 16,
Sandvika, NO-1303, Norway

Shan Huang, Atilla Incecik

University of Strathclyde,
100 Montrose Street,
Glasgow, G4 0LZ, United Kingdom

Contributed by the Ocean, Offshore, and Arctic Engineering Division of ASME for publication in the JOURNAL OF OFFSHORE MECHANICS AND ARCTIC ENGINEERING. Manuscript received June 18, 2013; final manuscript received March 9, 2014; published online April 15, 2014. Assoc. Editor: Dong S. Jeng.

J. Offshore Mech. Arct. Eng 136(3), 032001 (Apr 15, 2014) (8 pages) Paper No: OMAE-13-1058; doi: 10.1115/1.4027177 History: Received June 18, 2013; Revised March 09, 2014

A steel catenary riser (SCR) attached to a floating platform at its upper end encounters oscillations in and near its touchdown zone (TDZ), which results in interaction with the seabed. Field observations and design analysis of SCRs show that the highest stress and greatest fatigue damage occurred near the touchdown point where the SCR first touches the seabed soil. The challenges regarding the fatigue damage assessment of an SCR in the TDZ are primarily because of the nonlinear behavior of SCR–seabed interaction and considerable uncertainty in seabed interaction modeling and geotechnical parameters. Analysis techniques have been developed in the two main areas: SCR–seabed interaction modeling and the influence of the uncertainty in the geotechnical parameters on the dynamic response and fatigue performance of SCRs in the TDZ. Initially, this study discusses the significance of SCR–seabed interaction on the response of an SCR for deepwater applications when subjected to random waves on soft clay using the commercial code OrcaFlex for nonlinear time domain simulation. In the next step, this study investigates the sensitivity of fatigue performance to geotechnical parameters through a parametric study. It is proven that employing the improved lateral SCR–seabed interaction model with accurate prediction of soil stiffness and riser penetration with cyclic loading enables us to obtain dynamic global riser performance in the TDZ with better accuracy. The fatigue analyses results prove that the confounding results indicated by the previous research studies on the SCR in the TDZ are due to different geotechnical parameters imposed with the seabed interaction model. The main benefit of employing nonlinear seabed approach is to capture the entity of realistic soil interaction behavior in modeling and analysis and to predict the likelihood of the fatigue damage of the SCR with seabed interaction, thereby minimizing the risk of the loss of the containment with the associated environmental impact.

Copyright © 2014 by ASME
Your Session has timed out. Please sign back in to continue.

References

Figures

Grahic Jump Location
Fig. 1

Soil model characteristics for different modes

Grahic Jump Location
Fig. 2

Lateral pipe soil interaction using trilinear model

Grahic Jump Location
Fig. 3

(a) SCR–seabed interaction problem, (b) schematic of TDZ attached with hysteretic nonlinear soil springs, and (c) riser–soil model

Grahic Jump Location
Fig. 4

Dynamic SCR–soil contact resistance in far load case

Grahic Jump Location
Fig. 5

SCR–seabed interaction response in the TDZ at an arc length 1410 m

Grahic Jump Location
Fig. 6

Dynamic SCR lateral oscillation for beam seas in TDZ (3 h simulation)

Grahic Jump Location
Fig. 7

SCR–seabed lateral interaction at an arc length 1225 m

Grahic Jump Location
Fig. 8

Influence of lateral soil models on riser penetration

Grahic Jump Location
Fig. 9

Y–displacement of SCR at the TDP

Grahic Jump Location
Fig. 10

DNV S-N curve in seawater/cathodic protection

Grahic Jump Location
Fig. 11

Fatigue life for SCR in the TDZ for different SCF values

Grahic Jump Location
Fig. 12

Effect of linear soil stiffness on SCR cumulative fatigue damage in the TDZ

Grahic Jump Location
Fig. 13

Normalized maximum stiffness effect on fatigue life in the TDZ at arc length 1217.5 m

Grahic Jump Location
Fig. 14

Normalized maximum stiffness effect on trench deepening in the TDZ

Grahic Jump Location
Fig. 15

Influence of maximum normalized stiffness and soil suction ratio on the predicted fatigue life

Tables

Errata

Discussions

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related Journal Articles
Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In