Improving the prediction of scour around submarine pipelines

Zhang, Zhiyong; Shi, Bing; Guo, Yakun; Chen, Daoyi

doi:10.1680/jmaen.2015.22

Cited by 7 publications

(7 citation statements)

References 18 publications

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“…Seen from Figure 14, the predicted values using Equation (6) were also in good agreement with the measured values and the relative error was also within 20%. As discussed in 3.3, the maximum scour depth under the bidirectional tidal current was on average 80% of that under the unidirectional steady current.…”

Section: Prediction Of Maximum Scour Depthsupporting

confidence: 70%

“…Local scour around submarine pipelines is a typical scour phenomenon in a marine environment. In past decades, extensive studies have been carried out to investigate the scour mechanism, scouring process and scour protection around submarine pipelines [1][2][3][4][5][6][7][8]. Mao (1986) [9] studied the scour characteristics under a steady current in an experimental flume and discussed the effect of vortices on the onset of scour.…”

Section: Introductionmentioning

confidence: 99%

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Scale Model Experiment on Local Scour around Submarine Pipelines under Bidirectional Tidal Currents

Zhang

Guo

Yuanping

et al. 2021

JMSE

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In nearshore regions, bidirectional tidal flow is the main hydrodynamic factor, which induces local scour around submarine pipelines. So far, most studies on scour around submarine pipelines only consider the action of unidirectional, steady currents and little attention has been paid to the situation of bidirectional tidal currents. To deeply understand scour characteristics and produce a more accurate prediction method in bidirectional tidal currents for engineering application, a series of laboratory scale experiments were conducted in a bidirectional current flume. The experiments were carried out at a length scale of 1:20 and the tidal currents were scaled with field measurements from Cezhen pipeline in Hangzhou Bay, China. The experimental results showed that under bidirectional tidal currents, the scour depth increased significantly during the first half of the tidal cycle and it only increased slightly when the flow of the tidal velocity was near maximum flood or ebb in the following tidal cycle. Compared with scour under a unidirectional steady current, the scour profile under a bidirectional tidal current was more symmetrical, and the scour depth in a bidirectional tidal current was on average 80% of that under a unidirectional, steady current based on maximum peak velocity. Based on previous research and the present experimental data, a more accurate fitted equation to predict the tidally induced live-bed scour depth around submarine pipelines was proposed and has been verified using field data from the Cezhen pipeline.

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Section: Prediction Of Maximum Scour Depthsupporting

confidence: 70%

Section: Introductionmentioning

confidence: 99%

Scale Model Experiment on Local Scour around Submarine Pipelines under Bidirectional Tidal Currents

Zhang

Guo

Yuanping

et al. 2021

JMSE

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“…Offshore Pipelines have been one of key offshore installations for the offshore oil and gas industry, due to the growth of development of marine resources. In the marine environments, the existence of a pipeline changes the flow pattern and promotes the ability of sediment transport, which further affects the scour process [1][2][3]. The development of scour beneath pipelines can cause a free spanning pipeline that will cause further structural damage.…”

Section: Introductionmentioning

confidence: 99%

The Role of 2D Seepage on Sediment Incipient Motion around a Pipeline

Zhai

Jeng

Guo

2021

JMSE

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Pipelines have been used as one of the main transportation methods for the offshore industry, with increasing activities in marine resources recently. Prediction of seabed instability is one of key factors that must be taken into consideration for an offshore pipeline project. As the first step of the scour process, sediment incipient motion has been intensively studied in the past. Most previous investigations didn’t consider the wave-induced seepage in the elevation of sediment motion. In this paper, two-dimensional seepage was considered to modify the conventional Shields number and its associated impact on sediment incipient motion around the trenched pipeline was investigated. Both flat and sloping seabeds are considered. The numerical results indicated that a peak or valley of the modified Shields number was formed below the pipeline and horizontal seepage flow tremendously impact the sediment motion in the vicinity of the pipeline. Parametric analysis concludes: the influence of the seepage around the pipeline becomes more significant in a large wave, shallow water in a seabed with large shear modulus and permeability, and larger pipeline diameter and smaller flow gap ratio. This will make soil particles be more easily dragged away from the seabed.

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“…However, with the increase in computing power, the ability to model scour numerically is becoming more routine. In this issue, the paper by Zhang et al (2016) clearly demonstrates the ability to model scour around subsea pipelines, albeit with the uncertainty related to insufficient field measurements against which to compare.Protecting the coast and coastal infrastructure against damaging storms and/or tsunami events requires careful design. The paper by Anastasaki et al (2016) investigates the performance of single-layer concrete units through numerical simulation using a combined finite-element method and discrete-element method (FemDem) approach.…”

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confidence: 99%

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confidence: 99%

Editorial

Harris¹

2016

Proceedings of the Institution of Civil Engineers - Maritime En

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It is an honour to be taking over as chair of Maritime Engineering's editorial advisory panel. I would like to thank Kevin Burgess as former chair for the direction he has given the journal and for ensuring the continued success of the journal in providing a forum to share experiences of best practice, lessons learnt, innovative and novel techniques and methods and understanding.Having served previously as a panel member under the direction of Brian O'Connor and Rachel Fowler when the journal was relaunched a number of years ago, it feels a little like returning home. With an early career spent as a researcher before moving into consultancy, 29 years on I find myself looking back on how things have changed both within academia and industry and how meeting future challenges in maritime infrastructure will require partnerships between government, industry and universities.As engineers and scientists we live and work in world that is continually being reshaped through natural and anthropogenic action. With continued expansion in global population, these processes may sometimes be at odds with the demands of society and it is the responsibility of engineers and scientists to help manage the dynamic environment in which we live and to work to ensure the competing demands for finite resources can be satisfied in a sustainable manner. In addition to this, the dynamic and energetic environments in which these processes take place occur under a changing climate. From the tidal limit to the open oceans, the need to understand better the many processes that drive these changes is as relevant today as it was for those engineers and scientists who have gone before us.With a significant increase in seabed infrastructure being constructed (cables, pipelines, subsea structures, offshore structures) geohazards such as seismic events, landslips and submarine mass failures pose a risk to this infrastructure. Tsunamis, whether earthquake generated, which is the primary trigger (of the order of 70-80%), or resulting from slope failures either land based or subsea, can be enormously destructive, with loss of lives and damage to infrastructure such as occurred during the great Alaska earthquake of 1964 (Plafker et al., 1969). Therefore, the paper by Jaimes et al. (2016) in this issue is pertinent and important in proposing a methodology to identify tsunami hazard through the development of regional flood hazard maps, allowing the results to be used for coastal management, tsunami mitigation measures and more detailed risk analysis.Scour is also a hazard, and is both a hydrodynamic and geotechnical process as it relates to the movement of the seabed sediment as a result of the flow of water away from a structure, while the soil conditions are described by geotechnical parameters concerning the reduction in ground level around a structure.A scour hazard assessment may be performed at a variety of levels. In its most simplistic form this could consist of an analysis of seabed features such as bedforms to identify seabed mobility in sands...

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Improving the prediction of scour around submarine pipelines

Cited by 7 publications

References 18 publications

Scale Model Experiment on Local Scour around Submarine Pipelines under Bidirectional Tidal Currents

Scale Model Experiment on Local Scour around Submarine Pipelines under Bidirectional Tidal Currents

The Role of 2D Seepage on Sediment Incipient Motion around a Pipeline

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