Bedform evolution around a submarine pipeline and its effects on wave-induced forces under regular waves

Xu, Jishang; Li, Guangxue; Dong, Ping; Shi, Jianghong

doi:10.1016/j.oceaneng.2009.10.002

Cited by 30 publications

(10 citation statements)

References 24 publications

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“…The equilibrium scour depth, also defined as ultimate scour depth (e.g., see [21,25]), is the maximum depth observed under the pipeline when the scour process reaches a steady state, i.e. when the bed shear stress under the pipeline becomes constant and equal to an undisturbed value (e.g., see [8,18]).…”

Section: Theoretical Analysismentioning

confidence: 99%

“…A second experiment, carried out in the wave flume of the laboratory of Shengli Petroleum Manage Bureau (China) and described in [25] and [28] (hereafter XU10 and ZH11, respectively), aimed at investigating the soil behavior around a pipeline that was either half buried or resting on the seabed. The authors defined the tested soils as sand (d 50 = 0.287), sandy silt (d 50 = 0.057) and silt (d 50 = 0.034), each characterized by a specific clay content.…”

Section: Available Experimental Datamentioning

confidence: 99%

“…We first analyze some laboratory tests carried out by Vijaya Kumar et al [21], Xu et al [25] and Zhou et al [28] that focused on the scouring around a horizontal cylinder lying on a cohesive bed, subject to waves and currents. The specific purpose is that of finding a new formula for the prediction of the equilibrium scour depth under submarine pipelines.…”

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Scour depth under pipelines placed on weakly cohesive soils

Postacchini

Brocchini

2015

Applied Ocean Research

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Section: Theoretical Analysismentioning

confidence: 99%

Section: Available Experimental Datamentioning

confidence: 99%

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Scour depth under pipelines placed on weakly cohesive soils

Postacchini

Brocchini

2015

Applied Ocean Research

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“…For a partially buried cylinder, both hydrodynamic forces and the flow features have been reasonably researched (Jacobsen, Bryndum & Bonde 1989;Cokgor & Avci 2001;Gao et al 2011;Akoz 2012). Due to its natural process, the hydrodynamic loading is usually studied concurrently with the bed-form evolution and the pipe-soil interaction (Xu et al 2010;Gao, Gu & Jeng 2003). For a cylinder buried in an impermeable bed, the reduction in the force coefficient were found to be substantial, especially for the in-line force (Jacobsen et al 1989).…”

Section: Introductionmentioning

confidence: 99%

The hydrodynamic forces on a circular cylinder in proximity to a wall with intermittent contact in steady current

Tong

Cheng

et al. 2017

Ocean Engineering

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We present a three-dimensional Large Eddy Simulations (LES) study on the hydrodynamics of a circular cylinder close to a wall. Intermittent gaps between the cylinder and wall, forming spanning and non-spanning sections along the span are considered. This geometry setting represents an idealized model of pipelines laid on an uneven seabed. As compared to that of the corresponding spanwise-uniform cylinders, the drag coefficient on spanning sections is generally smaller, while the drag on non-spanning sections is slightly larger. Large amplitudes of the sectional forces are observed, partially due to the variations of the gap flow under the spanned sections. Flow deflection from the non-spanning section to the spanning section induces changes in local force and pressure distributions. Despite these changes, the mean force on the cylinder with intermittent contact as a whole is shown to be reasonably estimated by pro rata of forces from spanwiseuniform cylinders over the parameter space considered in this study. Keywords:hydrodynamic force submarine pipeline zebraic spanning steady flow

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“…The variation of vertical force with different depth of burial was provided in figures but nothing is described on why the trend of vertical wave force was different from the horizontal force variation due to different burial of the pipeline. Xu et al (2010) has carried out studies on bed form evolution around a submarine pipeline and its effects on wave-induced forces under regular waves. The aim of the study was to investigate the scour formation around a submarine pipeline initially, either resting on or half buried in the seabed under regular wave action by means of a series of wave tank experiments, and to evaluate the influence of the scour on the hydrodynamic forces exerted on the pipeline.…”

Section: Introductionmentioning

confidence: 99%

An approach to estimate the optimal depth of burial of crude oil pipelines for different marine conditions in Kuwait

Neelamani¹,

Al-Banaa²

2014

J Engin Res

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Crude oil export is the main business in Kuwait. To transfer the crude oil from land to the ships moored in deeper marine water, submarine pipelines are used. Kuwait is also planning to increase the export to 4.0 million barrel/day in the future and hence need more export terminals, which in turn need more submarine pipelines. One of the challenging problems here is selection of optimum burial depth of the submarine pipeline for the prevailing design condition and soil type. The optimum burial depth of submarine pipeline is the depth at which the pipeline will be stable during the design environmental conditions. It depends on the reduction of wave forces due to burial in the seafloor. Also, the wave forces on the pipeline at any depth of burial depend on the wave characters, hydraulic properties of the sea bed soil and all other marine environmental parameters. Physical modeling is used as tool for assessing the wave forces on the pipeline model for a wide range of wave conditions, for different burial depths and for four types of cohesion-less soil types from Kuwaiti coastal area, covering hydraulic conductivity in the range of 0.286 to 1.84 mm/s. It is found that for all the four soil types, the horizontal wave force reduces with increase in depth of burial, whereas the vertical force generally increases for half buried condition, mainly due to the significant change in the magnitude as well as the phase lag between the hydrodynamic water pressures on the top and bottom of the pipe. Among the soils, well graded soil is found to be good for half burial of pipeline, since the least vertical force is experienced for this soil type. On the other hand, uniformly graded and low hydraulic conductivity soil (like Al-Koot soil with hydraulic conductivity of 0.286 mm/s) attracts the maximum vertical force for half burial case. But, such soil type is found to be good for full burial or further increase of burial, since it is found to attract less vertical wave force, when compared to the soils with high hydraulic conductivity (1.84 mm/s from Shuaiba coast). From the detailed investigations and case study analysis, the minimum safe burial depth for a 1.0 m steel pipe is 1.5 m to 2.0 m for transporting crude oil in Kuwaiti marine environment. The results of this study can be used to select the minimum safe burial depth in a range of cohesionless soils and for a range of marine wave conditions. DOI 10.7603/s40632-014-0013-0 An approach to estimate the optimal depth of burial of crude oil pipelines for different marine conditions in Kuwait 44

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Bedform evolution around a submarine pipeline and its effects on wave-induced forces under regular waves

Cited by 30 publications

References 24 publications

Scour depth under pipelines placed on weakly cohesive soils

Scour depth under pipelines placed on weakly cohesive soils

The hydrodynamic forces on a circular cylinder in proximity to a wall with intermittent contact in steady current

An approach to estimate the optimal depth of burial of crude oil pipelines for different marine conditions in Kuwait

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