Pipe–seabed interaction

David White, Mark Bransby

Research output: Chapter in Book/Conference paperEntry for encyclopedia/dictionary

Abstract

Subsea pipelines rest on or in the seabed, and therefore their behavior and condition depends on pipe–seabed interactions. Pipelines expand and contract during operation and can also be loaded by hydrodynamic action, turbidity flows, or debris flows. These actions are resisted by seabed reaction forces in the vertical, axial, and lateral directions.

In some situations, the pipeline may be deliberately buried, for example, to allow overtrawling, provide thermal insulation, or prevent expansion‐induced buckling. However, in many cases, the pipeline may be laid directly onto the seabed. It may self‐bury through the action of sediment transport, remain only partially embedded into the soil, or some intermittent combination of these effects along its route.

Assessments of pipe–seabed interaction forces for all the abovementioned burial conditions begin with estimation of the as‐laid (or as‐constructed) embedment. Classical methods such as limit plasticity underpin solutions for embedment and the limiting pipe–soil resistance in each direction. The critical uncertainties are usually the operative soil strength—which is affected by the seabed disturbance during the lay (or backfilling) process and throughout the operating life—and the pipeline embedment (or cover depth). Specific geotechnical testing technologies have evolved to reduce uncertainties in pipe–seabed assessments, including tools for determining the near‐seabed (and disturbed) soil strength and the pipe–soil interface strength at very low stresses. The associated analysis methods also aim to quantify the variability of the seabed reaction forces along the pipeline.

The above mentioned predictions of pipe–seabed interaction behavior are performed to feed into structural analyses of the pipeline, which often use a reliability‐based framework. Pipe–soil interaction assessments require close collaboration between the pipeline and geotechnical experts due to the inherent influence of soil–structure interaction, as well as the aim of tailoring the geotechnical assessment to address the particular design criticalities, which vary depending on the seabed and pipeline conditions.
Original languageEnglish
Title of host publicationEncyclopedia of Maritime and Offshore Engineering
Place of PublicationUK
PublisherJohn Wiley & Sons
ISBN (Electronic)9781118476406
DOIs
Publication statusPublished - 2018

Fingerprint

soil strength
buckling
debris flow
plasticity
sediment transport
turbidity
soil
hydrodynamics
disturbance
prediction
method
contract
effect
thermal insulation
analysis

Cite this

White, D., & Bransby, M. (2018). Pipe–seabed interaction. In Encyclopedia of Maritime and Offshore Engineering UK: John Wiley & Sons. https://doi.org/10.1002/9781118476406.emoe536
White, David ; Bransby, Mark. / Pipe–seabed interaction. Encyclopedia of Maritime and Offshore Engineering. UK : John Wiley & Sons, 2018.
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White, D & Bransby, M 2018, Pipe–seabed interaction. in Encyclopedia of Maritime and Offshore Engineering. John Wiley & Sons, UK. https://doi.org/10.1002/9781118476406.emoe536

Pipe–seabed interaction. / White, David; Bransby, Mark.

Encyclopedia of Maritime and Offshore Engineering. UK : John Wiley & Sons, 2018.

Research output: Chapter in Book/Conference paperEntry for encyclopedia/dictionary

TY - CHAP

T1 - Pipe–seabed interaction

AU - White, David

AU - Bransby, Mark

PY - 2018

Y1 - 2018

N2 - Subsea pipelines rest on or in the seabed, and therefore their behavior and condition depends on pipe–seabed interactions. Pipelines expand and contract during operation and can also be loaded by hydrodynamic action, turbidity flows, or debris flows. These actions are resisted by seabed reaction forces in the vertical, axial, and lateral directions.In some situations, the pipeline may be deliberately buried, for example, to allow overtrawling, provide thermal insulation, or prevent expansion‐induced buckling. However, in many cases, the pipeline may be laid directly onto the seabed. It may self‐bury through the action of sediment transport, remain only partially embedded into the soil, or some intermittent combination of these effects along its route.Assessments of pipe–seabed interaction forces for all the abovementioned burial conditions begin with estimation of the as‐laid (or as‐constructed) embedment. Classical methods such as limit plasticity underpin solutions for embedment and the limiting pipe–soil resistance in each direction. The critical uncertainties are usually the operative soil strength—which is affected by the seabed disturbance during the lay (or backfilling) process and throughout the operating life—and the pipeline embedment (or cover depth). Specific geotechnical testing technologies have evolved to reduce uncertainties in pipe–seabed assessments, including tools for determining the near‐seabed (and disturbed) soil strength and the pipe–soil interface strength at very low stresses. The associated analysis methods also aim to quantify the variability of the seabed reaction forces along the pipeline.The above mentioned predictions of pipe–seabed interaction behavior are performed to feed into structural analyses of the pipeline, which often use a reliability‐based framework. Pipe–soil interaction assessments require close collaboration between the pipeline and geotechnical experts due to the inherent influence of soil–structure interaction, as well as the aim of tailoring the geotechnical assessment to address the particular design criticalities, which vary depending on the seabed and pipeline conditions.

AB - Subsea pipelines rest on or in the seabed, and therefore their behavior and condition depends on pipe–seabed interactions. Pipelines expand and contract during operation and can also be loaded by hydrodynamic action, turbidity flows, or debris flows. These actions are resisted by seabed reaction forces in the vertical, axial, and lateral directions.In some situations, the pipeline may be deliberately buried, for example, to allow overtrawling, provide thermal insulation, or prevent expansion‐induced buckling. However, in many cases, the pipeline may be laid directly onto the seabed. It may self‐bury through the action of sediment transport, remain only partially embedded into the soil, or some intermittent combination of these effects along its route.Assessments of pipe–seabed interaction forces for all the abovementioned burial conditions begin with estimation of the as‐laid (or as‐constructed) embedment. Classical methods such as limit plasticity underpin solutions for embedment and the limiting pipe–soil resistance in each direction. The critical uncertainties are usually the operative soil strength—which is affected by the seabed disturbance during the lay (or backfilling) process and throughout the operating life—and the pipeline embedment (or cover depth). Specific geotechnical testing technologies have evolved to reduce uncertainties in pipe–seabed assessments, including tools for determining the near‐seabed (and disturbed) soil strength and the pipe–soil interface strength at very low stresses. The associated analysis methods also aim to quantify the variability of the seabed reaction forces along the pipeline.The above mentioned predictions of pipe–seabed interaction behavior are performed to feed into structural analyses of the pipeline, which often use a reliability‐based framework. Pipe–soil interaction assessments require close collaboration between the pipeline and geotechnical experts due to the inherent influence of soil–structure interaction, as well as the aim of tailoring the geotechnical assessment to address the particular design criticalities, which vary depending on the seabed and pipeline conditions.

U2 - 10.1002/9781118476406.emoe536

DO - 10.1002/9781118476406.emoe536

M3 - Entry for encyclopedia/dictionary

BT - Encyclopedia of Maritime and Offshore Engineering

PB - John Wiley & Sons

CY - UK

ER -

White D, Bransby M. Pipe–seabed interaction. In Encyclopedia of Maritime and Offshore Engineering. UK: John Wiley & Sons. 2018 https://doi.org/10.1002/9781118476406.emoe536