The Mechanics of Scour in the Marine Environment

Sumer, B. Mutlu; Fredsøe, Jørgen

doi:10.1142/4942

Cited by 589 publications

(620 citation statements)

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“…This pressure drop further induces the seepage flow within the soil underneath the pipe. With the further increase of the current velocity, the critical state for onset of pipeline spanning is finally reached and a mixture of sand and water breaks through the space just at the downstream of the pipe [5] . In those small-scale flume experiments, it is very difficult to measure the pore pressure to obtain the distribution of the hydraulic gradients in the soil adjacent to the embedded pipe.…”

Section: Examination Of Blockage Effectsmentioning

confidence: 99%

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Flow-Pipe-Seepage Coupling Analysis of Spanning Initiation of a Partially-Embedded Pipeline

Gao

Luo

2010

J Hydrodyn

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Abstract:The initiation of pipeline spanning involves the coupling between the flow over the pipeline and the seepage-flow in the soil underneath the pipeline. The pipeline spanning initiation is experimentally observed and discussed in this article. It is qualitatively indicated that the pressure-drop induced soil seepage failure is the predominant cause for pipeline spanning initiation. A flow-pipe-seepage sequential coupling Finite Element Method (FEM) model is proposed to simulate the coupling between the water flow-field and the soil seepage-field. A critical hydraulic gradient is obtained for oblique seepage failure of the sand in the direction tangent to the pipe. Parametric study is performed to investigate the effects of inflow velocity, pipe embedment on the pressure-drop, and the effects of soil internal friction angle and pipe embedment-to-diameter ratio on the critical flow velocity for pipeline spanning initiation. It is indicated that the dimensionless critical flow velocity changes approximately linearly with the soil internal friction angle for the submarine pipeline partially-embedded in a sandy seabed.

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Section: Examination Of Blockage Effectsmentioning

confidence: 99%

“…In the past few decades, the mechanism of the initiation of pipeline spanning underneath pipelines in ocean environments has attracted numerous studies [5] . The onset of pipeline spanning around the pipeline in steady currents was mainly investigated experimentally, such as the studies by Mao [6] , Chiew [7] , and Sumer et al [8] .…”

Section: Introductionmentioning

confidence: 99%

Flow-Pipe-Seepage Coupling Analysis of Spanning Initiation of a Partially-Embedded Pipeline

Gao

Luo

2010

J Hydrodyn

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“…This is because no model for coupling two mechanisms has been available yet. To date, there is no model for the determination the oscillating shear stress at the instant during cyclic loading [11] . Therefore, we decouple two mechanisms in this study.…”

Section: Theoretical Formulationmentioning

confidence: 99%

Ocean waves propagating over a porous seabed: Residual and oscillatory mechanisms

et al. 2007

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Two mechanisms for the wave-induced pore pressures in a porous seabed, i.e. oscillatory and residual excess pore pressures, have been observed in laboratory experiments and field measurements. Most previous investigations have focused on one of the mechanisms individually. In this paper, an analytical solution for the wave-induced residual pore pressure, which is not available yet, is derived, and compared with the existing experimental data. With the new solution, a parametric analysis is performed to clarify the applicable ranges of two mechanisms. Then, a simplified approximation for the prediction of wave-induced liquefaction potential is proposed for engineering practice.seabed, pore pressure, residual, oscillatory, wave loading One of the important marine geotechnical engineering considerations for many engineering installations in oceanic environments, such as platform, pipeline and anchors, is the liquefaction potential of seabed due to ocean waves. Numerous examples of liquefaction have been reported in the literature, such as, floatation of pipeline during storm [1] , sinking of several measuring instructions in Mississippi Delta [2] and subsidence of offshore breakwaters at Niagata Coast, Japan [3] . Two significant mechanisms accounting for wave-induced soil response, including oscillatory pore pressure and residual pore pressure, have been observed in laboratory experiments and field measurements [4] , as shown in Figure 1. The first mechanism, termed as transient or oscillatory excess pore pressure, is accompanied by the attenuation of amplitude and the phase lag in pore pressure changes [5,6] . This mechanism is more important for unsaturated marine sediments and deeper water region. The second mechanism, termed as the residual pore pressure, is the build-up of excess pore pressure caused by contraction of the soil under the action of cyclic loading [7,8] . This mechanism is similar to the earthquake-induced pore pressure accumulation.Numerous investigations for ocean waves propagating over a porous seabed have been carried

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“…Scouring is one of the threats to the foundational stability of both riverine and maritime structures. Although flow-induced scour around bridge piers has received significant attention for many years, wave-induced scour around marine structures has not become a topic of interest to researchers till the 1990's (Bricker et al, 2012;Matutano et al, 2013;Negro et al, 2014;Sumer and Fredsøe, 2002;Whitehouse, 1998). The presence of marine structures in a coastal flow regime changes the flow pattern in the immediate neighbourhood of the structures.…”

Section: Introductionmentioning

confidence: 99%

“…Liquefaction is due to not only earthquakes, such as the catastrophic failures in Alaska andNiigata in 1964 (De Alba et al, 1976) or the recent disaster in Japan (Lai et al, 2013), but also waves. Momentary liquefaction occurs during the passage of wave troughs; more importantly, residual liquefaction occurs when the soil on the seabed is subjected to continuous wave loading (see Sumer and Fredsøe (2002) for a more in-depth explanation and Jeng (2003) for a comprehensive review).…”

Section: Introductionmentioning

confidence: 99%

Sinking of concrete modules into a sandy seabed: A case study

Muñoz-Pérez

Khan-Mozahedy

Neves

et al. 2015

Coastal Engineering

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a b s t r a c tThree submerged coastal structures on the sandy seabed at Santa Maria del Mar (SMM) Beach in Southwest Spain were monitored during the six months after installation, starting in November of 2005. The monitoring evaluated the self-burial phenomenon of the 40 precast modular concrete elements of the three structures. Assessment included scouring around the structures, their vertical movement, the sinking velocity of the modules and the resulting beach profiles. Pressure sensors and precision topographies permitted continuous monitoring of the self-burial process for the first time in a full-scale case. Comparison of two bathymetries (one performed immediately prior to installation and another performed six months after installation) indicated slight accretion of the seabed, whereas intermediate topographic surveys indicated extensive scouring around the structures. The three structures began sinking into the sandy bottom platform immediately after placement and continued until they reached the rocky bottom. This study implemented a new methodology using pressure sensors attached to the concrete modules to monitor the structural sinking. Unexpectedly, the average sinking speed was extremely rapid at approximately 3-6 cm/day; 50% of the height of the element was reached in three to six weeks. The results of this study are also compared with the results of other full-scale cases. Among other conclusions, data from this study indicated that the sinking rate of the modules in SMM Beach was one order of magnitude greater than the other values.

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The Mechanics of Scour in the Marine Environment

Cited by 589 publications

References 0 publications

Flow-Pipe-Seepage Coupling Analysis of Spanning Initiation of a Partially-Embedded Pipeline

Flow-Pipe-Seepage Coupling Analysis of Spanning Initiation of a Partially-Embedded Pipeline

Ocean waves propagating over a porous seabed: Residual and oscillatory mechanisms

Sinking of concrete modules into a sandy seabed: A case study

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