Experimental investigation of the equilibrium scour depth below submerged pipes both in live-bed and clear-water regimes under the wave effect

Dogan, Mustafa; Aksoy, Aysegul Ozgenc; Arisoy, Yalçìn; Güney, Mehmet Şükrü; Abdi, Vahid

doi:10.1016/j.apor.2018.08.010

Cited by 12 publications

(3 citation statements)

References 12 publications

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“…Over the last decade, a large number of AI approaches have been employed prosperously to obtain an accurate estimation of the local scour depth below pipelines exposed to currents and regular waves. In fact, Artificial A large number of experimental studies have been carried out to better understand scouring mechanisms at submarine pipelines; the papers from [4][5][6][7][8][9][10][11][12][13][14] in the references section are some examples. Generally, all the experimental studies were carried out in three distinctive flow conditions: (1) Current, (2) regular wave, and (3) combined current and wave.…”

Section: Introductionmentioning

confidence: 99%

Exploring 3D Wave-Induced Scouring Patterns around Subsea Pipelines with Artificial Intelligence Techniques

Najafzadeh

Oliveto

2021

Applied Sciences

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Subsea pipelines carry oil or natural gas over long distances of the seabed, but fluid leakage due to a failure of the pipeline can culminate in huge environmental disasters. Scouring process may take place beneath pipelines due to current and/or wave action, causing pipeline suspension and leading to the risk of pipeline failure. The resulting morphological variations of the seabed propagate not only below and normally to the pipeline but also along the pipeline itself. Therefore, 3D scouring patterns need to be considered. Mainly based on the experimental works at laboratory scale by Cheng and coworkers, in this study, Artificial Intelligent (AI) techniques are employed to present new equations for predicting three dimensional current- and wave-induced scour rates around subsea pipelines. These equations are given in terms of key dimensionless parameters, among which are the Shields’ parameter, the Keulegan–Carpenter number, relative embedment depth, and wave/current angle of attach. Using various statistical benchmarks, the efficiency of AI-models-based regression equations is assessed. The proposed predictive models perform much better than the existing empirical equations from literature. Even more interestingly, they exhibit a clear physical consistence and allow for highlighting the relative importance of the key dimensionless variables governing the scouring patterns.

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Section: Introductionmentioning

confidence: 99%

Exploring 3D Wave-Induced Scouring Patterns around Subsea Pipelines with Artificial Intelligence Techniques

Najafzadeh

Oliveto

2021

Applied Sciences

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“…Scour under an underwater pipeline has been previously investigated both experimentally and numerically. Laboratory experiment studies have focused on the onset of scour [2,3], tunnel and lee-wake erosion [4], the mechanism of three-dimensional scour hole development [5,6], the spanwise scour propagation rate [7][8][9], and the equilibrium scour depth [10]. Numerical simulation has also been widely used in the investigations on the aspects above [11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Visualization of the Onset of Scour under a Pipeline in Waves

et al. 2020

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This paper visualizes the onset of scour under a pipeline in regular waves and studies the mechanism in this process. After the test started, the sand particles near the downstream mudline began to oscillate periodically, probably due to the distribution pattern of the seepage hydraulic gradient under the pipeline as well as asymmetric waves. As the wave height gradually increased, the sand under the pipeline began to oscillate at increasing amplitude and the coverage of oscillation extended upstream. Some sand rushed out from the bottom of the pipeline, and the sand oscillated almost symmetrically around the bottom line of the pipeline thereafter. The oscillation amplitude of the sand particles continued to rise, probably due to a decrease in the seepage path under the pipeline and loosened sediment in the oscillation. The scour onset occurred after more sand rushed out from under the pipeline. The visualization results reproduced the delay in the scour onset reported previously, and related the delay to the aforementioned increase in sediment oscillation amplitude. This visualization can improve the understanding of the scour onset mechanism, and can serve as a guide to further investigate the critical conditions of scour onset and scour control countermeasures for offshore structures.

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“…Many investigations have focused on the two-dimensional scour under a pipeline, wherein the currents or waves are assumed to propagate towards the pipeline perpendicularly and the properties of the pipeline and the sediment are supposed to be identical along the pipeline [2]. These investigations have focused on the mechanism of the onset of scour [3,4], the equilibrium scour depth [5][6][7], the time scale of tunnel erosion [8][9][10], and field observations and tests [11,12]. Numerical simulation is also widely adopted in researches on the two-dimensional scour hole development process [13][14][15][16].…”

Section: Introductionmentioning

confidence: 99%

Visualization Tests on Variation of Scour Front under a Pipeline in Steady Currents

Xie

Zhu

2019

JMSE

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The intersection of the span shoulder and the scour hole under a pipeline, also called the scour front, can affect the scour hole extension rate and the bearing capacity of the span shoulder, which is associated with pipeline spanning and failure. Studies on scour front evolution are limited due to technical restrictions. In this study, visualization experiments on three-dimensional scour under a pipeline in steady currents were performed to reveal the evolution of the scour front at the beginning of scour process, and the parametric effects on the scour front pattern. The angle of scour front witnessed a steady drop at the start of the scour development process and fluctuated gently thereafter. This can be attributed to the decrease in the blockage effect over time. A gravitational movement was observed on the downstream end of the scour front, which is associated with the variation of fluid pressure along the scour front. The scour front pattern was described by the angle between the scour front and the streamwise direction. Parametric analysis showed that the averaged scour front angle climbs as the Froude number increases and the pipeline embedment drops. This phenomenon can be expounded by the intensified flow deflection near the span shoulder due to the enhancement of the pipeline blockage effect, caused by the ascending Froude number and descending pipeline embedment. The results of this study can be adopted in future mechanism investigations on the scour hole propagation rate and the failure analysis on the span shoulder.

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Experimental investigation of the equilibrium scour depth below submerged pipes both in live-bed and clear-water regimes under the wave effect

Cited by 12 publications

References 12 publications

Exploring 3D Wave-Induced Scouring Patterns around Subsea Pipelines with Artificial Intelligence Techniques

Exploring 3D Wave-Induced Scouring Patterns around Subsea Pipelines with Artificial Intelligence Techniques

Visualization of the Onset of Scour under a Pipeline in Waves

Visualization Tests on Variation of Scour Front under a Pipeline in Steady Currents

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