Geotechnical characteristics of deep-sea sediments from the North Atlantic and North Pacific oceans

Brandes, Horst G.

doi:10.1016/j.oceaneng.2010.09.001

Cited by 37 publications

(15 citation statements)

References 14 publications

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“…This is particularly encouraging, as measured shear strength deviates from s u ¼ 1 . 5z kPa between 15 and 30 m (Brandes, 2011), and the available shear strength data extend only to 35 m. The most significant deviations from the measured embedment are for tests 8605 and 8610. However, the predictions are in excellent agreement with the measured profile over the initial 45 m of embedment, at which point the predicted and measured velocities deviate.…”

Section: Application To Full-scale Testsmentioning

confidence: 87%

“…Freeman & Burdett, 1986;Freeman & Schüttenhelm, 1990;Baudet & Ho, 2004;Brandes, 2011). These data indicate that the seabed sediments consist of thick turbidite layers of up to 5 m, alternating with thin (,10 cm) layers of pelagic sediments.…”

Section: Application To Full-scale Testsmentioning

confidence: 93%

“…This is in reasonable agreement with s u =ó 9 v % 0 : 31 and k ¼ 1 . 35 kPa/m reported by Brandes (2011) over the upper 15 m. In view of these studies, the undrained shear strength profile for the field predictions has been approximated by s u ¼ 1 . 5z kPa.…”

Section: Application To Full-scale Testsmentioning

confidence: 99%

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Penetration of dynamically installed anchors in clay

O’Loughlin¹,

Richardson²,

Randolph³

et al. 2013

Géotechnique

107

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This paper utilises centrifuge data to explore the penetration response of dynamically installed anchors in normally consolidated clay. The data indicate that for anchors with no flukes, expected anchor tip embedment depths are two to three times the anchor length for impact velocities approaching 30 m/s, with a strong dependence on the net density of the anchor and smaller dependence on the impact velocity. Total energy, defined as the sum of the kinetic energy of the anchor at the mudline and the potential energy released as it penetrates the seabed, is shown to be a useful quantity for comparing the embedment depth of anchors with markedly different geometries and mass, impacting the soil at different velocities. The centrifuge data were used to calibrate an analytical embedment model, based on strain-rate-dependent shearing resistance and fluid mechanics drag resistance. The merit of the anchor embedment model has been demonstrated by predicting the final embedment depths for a series of offshore field trials to within 4% of the measurements.

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Section: Application To Full-scale Testsmentioning

confidence: 87%

Section: Application To Full-scale Testsmentioning

confidence: 93%

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Penetration of dynamically installed anchors in clay

O’Loughlin¹,

Richardson²,

Randolph³

et al. 2013

Géotechnique

107

View full text Add to dashboard Cite

show abstract

“…Regional differences of the sediments among the study sites are explained by the turbidite and contourite variability (Haskell and Johnson 1993;Brandes 2011), water depth and the distance from the coast (Thistle et al 1985;Rex et al 2005Rex et al , 2006Smith et al 2008). Turbidites are fine sediments, derived from turbidity currents and are found in the Norwegian Sea.…”

Section: Discussionmentioning

confidence: 99%

Marine Environment Around Iceland: Hydrography, Sediments and First Predictive Models of Icelandic Deep-sea Sediment Characteristics

Ostmann¹,

Schnurr²,

Arbizu³

2014

Polish Polar Research

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Sediment samples and hydrographic conditions were studied at 28 stations around Iceland. At these sites, Conductivity−Temperature−Depth (CTD) casts were con− ducted to collect hydrographic data and multicorer casts were conducted to collect data on sediment characteristics including grain size distribution, carbon and nitrogen concentra− tion, and chloroplastic pigment concentration. A total of 14 environmental predictors were used to model sediment characteristics around Iceland on regional scale. Two approaches were used: Multivariate Adaptation Regression Splines (MARS) and randomForest regres− sion models. RandomForest outperformed MARS in predicting grain size distribution. MARS models had a greater tendency to over− and underpredict sediment values in areas outside the environmental envelope defined by the training dataset. We provide first GIS layers on sediment characteristics around Iceland, that can be used as predictors in future models. Although models performed well, more samples, especially from the shelf areas, will be needed to improve the models in future.

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“…It seems more likely that sound velocity would increase moderately with depth as the sediment lost water under increased sediment load. However, Brandes (2011) reports that water content actually increased with depth in a large-diameter core of brown clay recovered nearby, probably due to changes in clay mineralogy. Thus, the vertical gradients are uncertain, and the measurements of Hamilton and Bachman are the best estimates of sound speed.…”

Section: Methodsmentioning

confidence: 98%

Ocean Bottom Seismometer Augmentation in the North Pacific (OBSANP) - cruise report

Stephen¹,

Worcester²,

Udovydchenkov³

et al. 2014

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The Ocean Bottom Seismometer Augmentation in the North Pacific Experiment (OBSANP, June-July, 2013, R/V Melville) addresses the coherence and depth dependence of deep-water ambient noise and signals. During the 2004 NPAL Experiment in the North Pacific Ocean, in addition to predicted ocean acoustic arrivals and deep shadow zone arrivals, we observed "deep seafloor arrivals" (DSFA) that were dominant on the seafloor Ocean Bottom Seismometer (OBS) (at about 5000m depth) but were absent or very weak on the Distributed Vertical Line Array (DVLA) (above 4250m depth). At least a subset of these arrivals correspond to bottomdiffracted surface-reflected (BDSR) paths from an out-of-plane seamount. BDSR arrivals are present throughout the water column, but at depths above the conjugate depth are obscured by ambient noise and PE predicted arrivals. On the 2004 NPAL/LOAPEX experiment BDSR paths yielded the largest amplitude seafloor arrivals for ranges from 500 to 3200km. The OBSANP experiment tests the hypothesis that BDSR paths contribute to the arrival structure on the deep seafloor even at short ranges (from near zero to 4-1/2CZ). The OBSANP cruise had three major research goals: a) identification and analysis of DSFA and BDSR arrivals occurring at short (1/2CZ) ranges in the 50 to 400Hz band, b) analysis of deep sea ambient noise in the band 0.03 to 80Hz, and c) analysis of the frequency dependence of BR and SRBR paths. On OBSANP we deployed a 32 element VLA from 12 to 1000m above the seafloor, eight short-period OBSs and four long-period OBSs and carried out a 15day transmission program using a J15-3 acoustic source. WHOI -2014 -03 OBSANP -Cruise Report

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Geotechnical characteristics of deep-sea sediments from the North Atlantic and North Pacific oceans

Cited by 37 publications

References 14 publications

Penetration of dynamically installed anchors in clay

Penetration of dynamically installed anchors in clay

Marine Environment Around Iceland: Hydrography, Sediments and First Predictive Models of Icelandic Deep-sea Sediment Characteristics

Ocean Bottom Seismometer Augmentation in the North Pacific (OBSANP) - cruise report

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