Sweeping behaviour of shallowly-embedded pipeline during cyclic lateral movement

Takatani, Tomiya

doi:10.1201/b10132-124

Cited by 1 publication

(2 citation statements)

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“…From the illustrations presented above, supported by further analysis detailed in Westgate et al (2009Westgate et al ( , 2010aWestgate et al ( , 2010b, the lay rate has a significant effect on as-laid embedment, as shown in simplified form in Figure 10. The local embedment is greatest, relative to nominal embedment (i.e.…”

Section: Observed Field Embedmentmentioning

confidence: 78%

“…The sleeper crossing process has been examined in detail in another study (Westgate et al 2010b), which presents numerical analyses showing the basis for the slight asymmetry observed. The observations suggest that both dynamic lay effects and the sleeper crossing process itself should be considered in assessing pipeline embedment adjacent to sleepers, since this has an important influence on the lateral buckling response which the sleeper is intended to control.…”

Section: Observed Field Embedmentmentioning

confidence: 99%

See 1 more Smart Citation

Pipeline Laying and Embedment in Soft Fine-grained Soils: Field Observations and Numerical Simulations

Westgate¹,

White²,

Randolph

et al. 2010

Proceedings of Offshore Technology Conference

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The as-laid embedment of offshore pipelines governs several aspects of pipeline design and lay route architecture. The observed as-laid embedment in soft soils is greater than would be predicted based on the static penetration resistance of the seabed using the in situ soil strength. Empirical 'dynamic embedment factors' are used to scale up this calculated embedment to estimate the as-laid value. The source of this discrepancy is dynamic lay effects, including the form and duration of any dynamic vessel and pipeline movements, and the seabed soil conditions. This study presents data to support an improved methodology to estimate the likely range of as-laid pipeline embedment. Existing theoretical models are reviewed, using aslaid pipeline survey data from five pipelines across two soft fine-grained soil sites. It is shown how the dynamic embedment in the field can be estimated by accounting separately for (i) a reduction in soil strength due to pipeline motions in the touchdown zone and (ii) an increase in the pipeline catenary bearing pressure due to vessel and pipeline dynamics. This represents a more robust methodology than the common industry practice of applying an empirical dynamic embedment factor to the calculated static embedment. Guidance on the pipeline embedment that occurs when the usual lay process is interrupted is also provided, for example at sleeper crossings and during weather-related downtime, in-line tee connections, abandonment and recovery activities, and pipeline termination assembly connections.

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Section: Observed Field Embedmentmentioning

confidence: 78%

Section: Observed Field Embedmentmentioning

confidence: 99%