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115606 - Predicting scour beneath subsea pipelines from existing small free span depths under steady currents.pdf (2.51 MB)

Predicting scour beneath subsea pipelines from existing small free span depths under steady currents

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posted on 2023-05-19, 03:35 authored by Lee, JY, McInerney, J, Remo Cossu, Zhi Quan LeongZhi Quan Leong, Alexander Forrest
An equation was developed to predict current-induced scour beneath subsea pipelines in areas with small span depths, S. Current equations for scour prediction are only applicable to partially buried pipelines. The existence of small span depths (i.e. S/D < 0.3) are of concern because the capacity for scour is higher at smaller span depths. Furthermore, it is impractical to perform rectification works, such as installing grout bags, under a pipeline with a small S/D. Full-scale two-dimensional Computational Fluid Dynamics (CFD) simulations were performed using the Reynolds-averaged Navier–Stokes approach and the Shear Stress Transport k-ω turbulence model. To predict the occurrence of scour, the computed maximum bed shear stress beneath the pipe was converted to the dimensionless Shields parameter, and compared with the critical Shields parameter based on the mean sediment grain size. The numerical setup was verified, and a good agreement was found between model-scale CFD data and experimental data. Field data were obtained to determine the mean grain size, far field current velocity and to measure the span depths along the surveyed pipe length. A trend line equation was fitted to the full-scale CFD data, whereby the maximum Shields parameter beneath the pipe can be calculated based on the undisturbed Shields parameter and S/D.

History

Publication title

Journal of Ocean Engineering and Science

Pagination

61-75

ISSN

2468-0133

Department/School

Australian Maritime College

Publisher

Elsevier

Place of publication

Netherlands

Rights statement

Copyright 2017 Shanghai Jiaotong University. Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0) https://creativecommons.org/licenses/by-nc-nd/4.0/

Repository Status

  • Open

Socio-economic Objectives

Pipeline transport

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