The fatigue life of a Steel Catenary Riser (SCR) near its touch-down zone is
substantially affected by its interaction with the seabed. Hence, accurate estimate of its
fatigue life requires the understanding and realistic modeling of the interaction between
them.
The interaction between SCR and the seabed depends on many factors, such as soil
properties, riser characteristics, and the development of trenching at the seafloor.
Existing approaches for modeling the seabed in interaction with a SCR approximate the
seabed soil by a linear or nonlinear spring and a dashpot which respectively represent the
stiffness and damping of the soil. However, they do not take into account certain
phenomena resulting from plastic deformation or degradation of the seabed soil, such as
trenching. In this study, a more realistic approach is developed for simulating the
interaction between a SCR and the seabed soil. In addition to the use of a realistic P-y
curve (where P stands for the supporting or resistance force of the seafloor and y for the
vertical penetration of the riser into the soil) to simulate the soil deformation during its interaction with a riser, it considers the development of a trench caused by continuous
poundings of a riser on the seabed and then its feedback effect on the variation of the
bending moment along the riser.
In this study, it has been found that trenching underneath a SCR may decrease the
maximum variation of bending moment near its touch-down zone. Since the variation of
the moment dictates the fatigue damage to the SCR, the results based on this approach
indicate that the trenching development at the seabed may increase the fatigue life of a
SCR and therefore, it may have important application to the design of a SCR.
| Identifer | oai:union.ndltd.org:tamu.edu/oai:repository.tamu.edu:1969.1/ETD-TAMU-2010-12-9016 |
| Date | 2010 December 1900 |
| Creators | Nakhaee, Ali |
| Contributors | Zhang, Jun |
| Source Sets | Texas A and M University |
| Language | en_US |
| Detected Language | English |
| Type | Book, Thesis, Electronic Dissertation, text |
| Format | application/pdf |
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