Field Measurements to Investigate Submerged Slope Failures

Duinen, Alexander van; Bezuijen, Adam; Ham, Geeralt van den; Hopman, Victor

doi:10.1007/978-3-319-00972-8_2

Cited by 6 publications

(6 citation statements)

References 8 publications

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“…The equation for the bank safety calculation for a liquefied flow slide (Van den Ham et al , ; Deltares, ) follows

\begin{matrix} right F ({SC}_{liquefaction}) & left = {(\frac{H_{normalf}}{24})}^{2.5} \cdot {(\frac{5}{\cot α_{normalf}})}^{5} \cdot {(\frac{1}{10})}^{- 10 (0.05 + ψ)} & right \\ right & left \cdot \frac{V_{local}}{V_{WS}} \cdot \frac{{SC}_{avg}}{L_{normalm}} {km yr}^{- 1} \end{matrix}

where ψ is the state parameter as a function of a cone penetration test according to the relation by Shuttle and Jefferies (), which is the average value of the state parameter in the soil layers between top and toe of the submerged slope, with a (cumulative) thickness of 5 m having the loosest packing (highest ψ ). A negative ψ indicates dense, dilative soils, whereas a positive ψ indicates loose contractive soils (see also Van Duinen et al , ). ψ is compared to the general value of 0.05 for the Western Scheldt (Van den Ham et al.…”

Section: Methodsmentioning

confidence: 99%

“…() argued that collapse of the slopes was dominated by breaching, there is no information on the actual process. Therefore, we considered that half of all flow slides were pure liquefaction flow slides, while the other half concerned pure breach flow slides (Van den Ham et al , , Van Duinen et al , ; Deltares, ). Eventually, the bank safety assessment could be written as follows:

\begin{matrix} right F_{SC} & left = [0.5 {(\frac{H_{normalR}}{24})}^{2.5} {(\frac{5}{\cot α_{normalR}})}^{5} + 0.5 {(\frac{H_{normalR}}{24})}^{5} {(\frac{5}{\cot α_{normalR}})}^{5}] & right \\ right & left \cdot \frac{V_{local}}{V_{WS}} {km yr}^{- 1} \end{matrix}

where the other variables are excluded, as these are considered to be constant within the Western Scheldt.…”

Section: Methodsmentioning

confidence: 99%

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Location and probability of shoal margin collapses in a sandy estuary

Dijk

Mastbergen

Ham

et al. 2018

Earth Surf Processes Landf

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Channel bank failure, and collapses of shoal margins and beaches due to flow slides, have been recorded in Dutch estuaries for the past 200 years but have hardly been recognized elsewhere. Current predictions lack forecasting capabilities, because they were validated and calibrated for historic data of cross-sections in specific systems, allowing local hindcast rather than location and probability forecasting. The objectives of this study were to investigate where on shoal margins collapses typically occur and what shoal margin collapse geometries and volumes are, such that we can predict their occurrence. We identified shoal margin collapses, generally completely submerged, from bathymetry data by analyzing digital elevation models of difference of the Western Scheldt for the period 1959-2015. We used the bathymetry data to determine the conditions for occurrence, specifically to obtain slope height and angle, and applied these variables in a shoal margin collapse predictor. We found 299 collapses along 300 km of shoal margin boundaries over 56 years, meaning that more than five collapses occur on average per year. The average shoal margin collapse body is well approximated by a 1/3 ellipsoid shape, covers on average an area of 34 000 m 2 and has an average volume of 100 000 m 3 . Shoal margin collapses occur mainly at locations where shoals take up a proportionally larger area than average in the cross-section of the entire estuary, and occur most frequently where lateral shoal margin displacement is low. A receiver operating characteristic curve shows that the forecasting method predicts the shoal margin collapse location well. We conclude that the locations of the shoal margin collapses are well predicted by the variation in conditions of the relative slope height and angle within the Western Scheldt, and likely locations are at laterally relatively stable shoal margins. This provides hypotheses aiding the recognition of these features in sandy estuaries worldwide.

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“…The equation for the bank safety calculation for a liquefied flow slide (Van den Ham et al , ; Deltares, ) follows

\begin{matrix} right F ({SC}_{liquefaction}) & left = {(\frac{H_{normalf}}{24})}^{2.5} \cdot {(\frac{5}{\cot α_{normalf}})}^{5} \cdot {(\frac{1}{10})}^{- 10 (0.05 + ψ)} & right \\ right & left \cdot \frac{V_{local}}{V_{WS}} \cdot \frac{{SC}_{avg}}{L_{normalm}} {km yr}^{- 1} \end{matrix}

Section: Methodsmentioning

confidence: 99%

\begin{matrix} right F_{SC} & left = [0.5 {(\frac{H_{normalR}}{24})}^{2.5} {(\frac{5}{\cot α_{normalR}})}^{5} + 0.5 {(\frac{H_{normalR}}{24})}^{5} {(\frac{5}{\cot α_{normalR}})}^{5}] & right \\ right & left \cdot \frac{V_{local}}{V_{WS}} {km yr}^{- 1} \end{matrix}

where the other variables are excluded, as these are considered to be constant within the Western Scheldt.…”

Section: Methodsmentioning

confidence: 99%

Location and probability of shoal margin collapses in a sandy estuary

Dijk

Mastbergen

Ham

et al. 2018

Earth Surf Processes Landf

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“…The Dutch dredging industry in the 1970s first identified breaching as an important production mechanism for stationary suction hopper dredgers. Currently, breaching is incorporated into corresponding safety assessments of dikes in the Netherlands, as it is an important failure mechanism [8].…”

Section: Breaching Flow Slidesmentioning

confidence: 99%

“…The existing literature reports many historical cases of large submarine flow slides worldwide (e.g., [3][4][5][6]). There is a long history of flow slide events in the Netherlands [7], particularly in the southwestern estuary of the Netherlands (Zeeland), where hundreds of flow slides have been observed since 1800 [8]. However, the observations were made after the flow slides had already occurred, as their timing is unpredictable, implying that the temporal development of the failure was not monitored.…”

Section: Introductionmentioning

confidence: 99%

Breaching Flow Slides and the Associated Turbidity Current

Alhaddad

Labeur

Uijttewaal

2020

JMSE

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This paper starts with surveying the state-of-the-art knowledge of breaching flow slides, with an emphasis on the relevant fluid mechanics. The governing physical processes of breaching flow slides are explained. The paper highlights the important roles of the associated turbidity current and the frequent surficial slides in increasing the erosion rate of sediment. It also identifies the weaknesses of the current breaching erosion models. Then, the three-equation model of Parker et al. is utilised to describe the coupled processes of breaching and turbidity currents. For comparison’s sake, the existing breaching erosion models are considered: Breusers, Mastbergen and Van Den Berg, and Van Rhee. The sand erosion rate and hydrodynamics of the current vary substantially between the erosion models. Crucially, these erosion models do not account for the surficial slides, nor have they been validated due to the scarcity of data on the associated turbidity current. This paper motivates further experimental studies, including detailed flow measurements, to develop an advanced erosion model. This will improve the fidelity of numerical simulations.

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“…On the 22 nd of July 2014, a large flow slide occurred along the tidal flat of Walsoorden profiling) were performed (Van Duinen et al, 2014). Pore-water pressure meters were installed in wells at 5m depth allowing continuous monitoring during the test (Mastbergen et al, 2016).…”

Section: Case Histories Of Breaching Flow Slidesmentioning

confidence: 99%

The influence of underwater embankment properties on breaching failures

Silva¹,

Rita²

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The influence of underwater embankment properties on breaching failures De invloed van de opbouw van onderwatertaluds op taludvervloeiing (met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. H.R.B.M. Kummeling, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op vrijdag 28 augustus 2020 des middags te 4.

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Field Measurements to Investigate Submerged Slope Failures

Cited by 6 publications

References 8 publications

Location and probability of shoal margin collapses in a sandy estuary

Location and probability of shoal margin collapses in a sandy estuary

Breaching Flow Slides and the Associated Turbidity Current

The influence of underwater embankment properties on breaching failures

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