Scour development around a jacket structure in combined waves and current conditions compared to monopile foundations

Welzel, Mario; Schendel, Alexander; Hildebrandt, Arndt; Schlurmann, Torsten

doi:10.1016/j.coastaleng.2019.103515

Cited by 48 publications

(55 citation statements)

References 20 publications

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“…As mentioned previously, the present tests were part of a larger investigation, in which the time dependent development of the scour around the jacket at different locations was measured and analyzed (cp. [12]). For this, measurements were carried out by means of echo sounding transducers with a diameter of ~1cm around pile 1 and pile 3 as well as in between the piles.…”

Section: Methodsmentioning

confidence: 99%

“…These echo sounders are additionally illustrated in Figure 2. For more detailed information about the experimental setup and procedure refer to Welzel et al [12]. As mentioned previously, the present tests were part of a larger investigation, in which the time dependent development of the scour around the jacket at different locations was measured and analyzed (cp.…”

Section: Methodsmentioning

confidence: 99%

“…It should be noted that the present physical model tests were part of a fundamental study previously described in [12]. While Welzel et al [12] focused on local scour depths, measured for a wide range of wave, wave-current and steady current conditions, the present study concentrates on the volume-based assessment of spatial erosion processes in the near-field and vicinity of the structure.…”

Section: Introductionmentioning

confidence: 95%

“…Even though the bed topography was measured, these studies were more focused on the local scour development for specific conditions rather than on the spatial scour development on a global extent. A literature study on model tests and field studies related to jacket-type foundations can be found in Welzel et al [12].…”

Section: Introductionmentioning

confidence: 99%

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Volume-Based Assessment of Erosion Patterns around a Hydrodynamic Transparent Offshore Structure

et al. 2019

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The present article presents results of a laboratory study on the assessment of erosion patterns around a hydrodynamic transparent offshore foundation exposed to combined waves and currents. The model tests were conducted under irregular, long-crested waves in a scale of 1:30 in a wave-current basin. A terrestrial 3D laser scanner was used to acquire data of the sediment surface around the foundation structure. Tests have been conducted systematically varying from wave- to current-dominated conditions. Different volume analyzing methods are introduced, which can be related for any offshore or coastal structure to disclose physical processes in complex erosion patterns. Empirical formulations are proposed for the quantification of spatially eroded sediment volumes and scour depths in the near-field and vicinity of the structure. Findings from the present study agree well with in-situ data stemming from the field. Contrasting spatial erosion development between experimental and in-situ data determines a stable maximum of erosion intensity at a distance of 1.25 A, 1.25 times the structure’s footprint A, as well as a global scour extent of 2.1–2.7 A within the present study and about 2.7–2.8 A from the field. By this means, a structure-induced environmental footprint as a measure for erosion of sediment affecting marine habitat is quantified.

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 95%

Section: Introductionmentioning

confidence: 99%

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Volume-Based Assessment of Erosion Patterns around a Hydrodynamic Transparent Offshore Structure

et al. 2019

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“…As an additional reference value for the scouring rate, the time scale T int is given in Table 2. The time scale is calculated as the integrated scour depth over time, an approach also applied by Fredsøe et al [21], Fuhrmann et al [22] or Welzel et al [23]:…”

Section: Time Development and Scouring Rate Of Maximum Scour Depthmentioning

confidence: 99%

Role and Impact of Hydrograph Shape on Tidal Current-Induced Scour in Physical-Modelling Environments

Schendel

Welzel

Hildebrandt

et al. 2019

Water

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For physical model tests, the time-varying characteristics of tidal currents are often simplified by a hydrograph following a shape of a unidirectional current or by resolving the tidal velocity signal into discrete steps of constant flow velocity. The influence of this generalization of the hydrograph's shape on the scouring process in tidal currents has not yet been investigated systematically, further increasing the uncertainty in the prediction of scour depth and rate. Therefore, hydraulic model tests were carried out to investigate and quantify the influence of the hydrograph shape on the scouring processes under tidal currents. Several different hydrographs including those with continuously changing velocities, constant unidirectional currents, square-tide velocities and stepped velocity time series were analyzed. Results show that the scouring process in tidal currents is characterized by concurrent sediment backfilling and displacement which can only be reproduced by hydrographs that incorporate a varying flow direction. However, if only a correct representation of final scour depths is of interest, similar scour depths as in tidal currents might be achieved by a constant, unidirectional current, provided that a suitable flow velocity is selected. The effective flow work approach was found capable to identify such suitable hydraulic loads with reasonable practical accuracy.

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GWK+: Erweiterung des Großen Wellenkanals – Analyse des Einlaufbereichs

2021

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Der notwendige Ausbau maritimer erneuerbarer Energien bedingt die eingehende Untersuchung von strukturellen Belastungsgrenzen und potenziellen Umwelteinflüssen von Offshore‐Strukturen. Großmaßstäbliche Versuchseinrichtungen nehmen hierbei eine wichtige Rolle ein, da nur hier Belastungen, die sich mit der Expansion von Offshore‐Strukturen in größere Wassertiefen ergeben, realitätsnah untersucht werden können. Von besonderer Bedeutung für die Bemessung von Offshore‐Strukturen ist eine realistische Abbildung der komplexen Überlagerung von Wellen und Strömung, die bisher nur in wenigen Versuchseinrichtungen großmaßstäblich möglich ist. Mit der Erweiterung des Großen Wellenkanals (GWK) in Hannover zum GWK+ wird ab 2022 die erste Versuchsanlage dieser Art in Deutschland zur Verfügung stehen. Die Planung und Konstruktion der Einleitung einer zusätzlichen Strömung in einen Wellenkanal mit dem Ziel der Erreichung natürlicher Strömungszustände stellt eine große Herausforderung dar. Als wesentliche strömungstechnische Komponente soll daher in diesem Beitrag die Entwicklung der Strömungseinleitung in den erweiterten GWK vom Entwurf bis hin zu einer Optimierung durch ein eigens hierfür geschaffenes 1:10‐Modell beschrieben werden. Einblicke in die Umsetzung, die strömungstechnischen Herausforderungen sowie die Optimierung der Strömungseinleitung in einen Wellenkanal mittels Leitwände und verstellbarer Lamellen sowie die Passfähigkeit eines 1/15‐Potenzgesetzes für das vertikale Strömungsprofil werden gegeben.

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Scour development around a jacket structure in combined waves and current conditions compared to monopile foundations

Cited by 48 publications

References 20 publications

Volume-Based Assessment of Erosion Patterns around a Hydrodynamic Transparent Offshore Structure

Volume-Based Assessment of Erosion Patterns around a Hydrodynamic Transparent Offshore Structure

Role and Impact of Hydrograph Shape on Tidal Current-Induced Scour in Physical-Modelling Environments

GWK+: Erweiterung des Großen Wellenkanals – Analyse des Einlaufbereichs

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