Scour below a subsea pipeline in time varying flow conditions

Zhang, Qin; Draper, Scott; Cheng, Liang; An, Hongwei

doi:10.1016/j.apor.2015.10.003

Cited by 16 publications

(7 citation statements)

References 34 publications

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“…Hence, the present experiments are in line with the conclusion of , that the scour depth following a change in flow conditions will tend to a new equilibrium based solely on the new wave condition. This conclusion is similarly backed by other experimental (Bayraktar et al, 2016;Zhang et al, 2016Zhang et al, , 2017 and numerical (Fuhrman et al, 2014;Bayraktar et al, 2016) research. Fuhrman et al (2014) also found that the equilibrium bed profiles (i.e.…”

Section: Scour Depth Time Series and Profilessupporting

confidence: 80%

“…Local pipeline scour and/or backfilling processes due to current and/or waves have been commonly studied both experimentally (e.g. Sumer and Fredsøe, 1990;Zhang et al, 2016;Bayraktar et al, 2016) as well as numerically (e.g. Brørs, 1999;Liang and Cheng, 2005;Kazeminezhad et al, 2012;Zanganeh et al, 2012;Fuhrman et al, 2014;Larsen et al, 2016).…”

Section: Introductionmentioning

confidence: 99%

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Generalized time scale for wave-induced backfilling beneath submarine pipelines

Bastian

Carstensen

Sui

et al. 2019

Coastal Engineering

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Section: Scour Depth Time Series and Profilessupporting

confidence: 80%

Section: Introductionmentioning

confidence: 99%

Generalized time scale for wave-induced backfilling beneath submarine pipelines

Bastian

Carstensen

Sui

et al. 2019

Coastal Engineering

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show abstract

“…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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“…The operating speed and precision for installing pipelines and other deep-sea equipment need to constantly improve to adapt to increasing developmental requirements [1,2]. Vessel motion and installation are highly sensitive to environmental changes during pipeline installation [3,4]. It is essential to acquire a better understanding of the marine environment during installation to provide these operations with higher accuracy, which can significantly help with planning pipeline installation.…”

Section: Introductionmentioning

confidence: 99%

Monitoring and Analysis of Wave Characteristics during Pipeline End Termination Installation

et al. 2019

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Pipeline end termination (PLET) installation is an essential part of offshore pipe-laying operation. Pipe-laying operations are sensitive to pipe-laying barge motion and marine environmental conditions. Monitoring the field environment can provide a reasonable basis for planning pipe-laying. Therefore, the measurement and analysis of sea wave motion is helpful for the control and operational safety of the pipeline and vessels. In this study, an environmental monitoring system was established to measure wave motion during PLET operation. Fourier transforms were used to process images that were acquired by ultra-high-frequency X-band marine radar to extract wave parameters. The resulting wave spectra, as measured each minute, were used to simulate real-time wave data and calculate wave characteristics and regressed wave frequency and direction spectrum throughout the PLET operation. The regressed frequency, spectral density, and direction spectra were compared with the theoretical spectra to evaluate their similarity and find the most similar spreading function in the operational area (the South China Sea). Gaussian fitting of real-time wave data was tested while using a classical method. The marginal distribution and joint density of the wave characteristics were estimated and then compared with theoretical distributions to find the most suitable model for improving marine environmental forecasting.

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Scour below a subsea pipeline in time varying flow conditions

Cited by 16 publications

References 34 publications

Generalized time scale for wave-induced backfilling beneath submarine pipelines

Generalized time scale for wave-induced backfilling beneath submarine pipelines

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

Monitoring and Analysis of Wave Characteristics during Pipeline End Termination Installation

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