Acoustic and physical property relationships in marine sediment

Bachman, Richard T.

doi:10.1121/1.392429

Cited by 72 publications

(60 citation statements)

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“…Along the 150m contour, grab sample measurements [1] show a mean grain size of 0.0156 mm (φ=6). While having a mean grain size is useful, there are large uncertainties in converting a grain size to geoacoustic properties [2] as shown in Fig 2. These uncertainties then translate to large propagation uncertainties as shown in Figure 3 (using RAM); at 10 km range the uncertainties are ~50 dB at the 95% confidence level. In some sense, this is an under-estimate of the uncertainties inasmuch as the uncertainty and variability along-track of the grain size estimate was not considered.…”

Section: Resultsmentioning

confidence: 99%

Predicting the Impact of Seabed Uncertainty and Variability on Propagation Uncertainty

Holland¹

2008

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LONG TERM GOALSDevelop capability for quantifying, predicting and exploiting (QPE) the impact of seabed uncertainty on sonar system performance. OBJECTIVESThe objectives are to: 1) develop techniques required to create a 2D geoacoustic uncertainty model (2D-GeUM) over an operationally significant area, 2) demonstrate techniques to create 2D-GeUM in area off northeast coast of Taiwan, and 3) demonstrate ability of 2D-GeUM to predict propagation uncertainty. APPROACHIn order to predict the impact of seabed geoacoustic uncertainties and variability on propagation uncertainty along a radial of interest, a 2D geoacoustic uncertainty model (2D-GeUM) is required. Such a model quantifies depth-and range-dependent geoacoustic properties and their uncertainties over the area of interest. For the QPE experiment, this will be in an area northeast of Taiwan, ~50 km x 50 km, including part of the Chilung shelf, the East China Sea shelf and upper slope.The approach exploits direct-path wide-angle seabed reflection data and geologic modeling as the basis for generating the 2D-GeUM. The components of the approach are shown in cartoon form in Figure 1. The 2D-GeUM is the key model for predicting the impact of seabed uncertainties and variability on TL uncertainties along a specified radial. Early results using data from a different shallow water area are very promising in terms of capturing the correct propagation uncertainties.

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Section: Resultsmentioning

confidence: 99%

Predicting the Impact of Seabed Uncertainty and Variability on Propagation Uncertainty

Holland¹

2008

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“…Or d'une manière générale, les mesures expérimen-tales de célérité des ondes sur des sédiments naturels donnent des valeurs supérieures à celles de WOOD (GREFFARD, 1969 ;HAMILTON et al, 1982 ;BACHMAN, 1985 ;ORSI et DUNN, 1990...). LAUGHTON (1957) à partir de l'étude de la compaction de divers sédiments naturels introduit pour sa part le concept d'incompressibilité de structure k = k w .…”

Section: Rappels Théoriquesunclassified

“…Il s'agit essentiellement de l'influence de la granulo métrie qui transparaît. Les études réalisées sur divers sédiments naturels ont donné de bonnes corrélations entre les paramètres grain moyen et pourcentage de grossiers sur la vitesse du son (GREFFARD, 1969 ;HAMILTON et al, 1982 ;BACHMAN, 1985). La relation vitesse-teneur en carbonate parfois observée est en grande partie due à la nature en majorité cal caire de la fraction grossière.…”

Section: Vitesse D U So N Et Porositéunclassified

Vitesse du son dans les sédiments marins durant les premiers stades du tassement

Guillaume¹,

Morlier²,

Viguier³

1991

Rev. Fr. Geotech.

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RésuméLa vitesse du son est mesurée dans des sédiments marins lors d'une étude expé-rimentale du tassement. Durant la phase de sédimentation, la vitesse du son diminue légèrement, puis lors de la phase de compaction elle s'accroît avec ta charge et la réduction de porosité (modèles de WOOD (1941) et de NOBES (1989). Le suivi du phénomène met en évidence le réarrangement graduel de la structure des particules et l'apparition de la rigidité pour une porosité seuil (environ 0,70). La différence de comportement acoustique entre les matériaux argileux et carbonatés résulte essentiellement de la granulométrie qui contrôle la réorganisation des grains. AbstractAn experimental study which measure the sound velocity during the settling of marine sediments is presented. In the first step the sound velocity slightly decrease during decantation stage, in the second step it increases with loading and porosity reduction during compaction stage [WOOD (1941) and NOBES (1989) models). The follow of the process shows the progressive rearrangement of particules structure and the acquisition of rigidity appears at a threshold porosity (about 0.70). Acoustical behaviour of argileous and calcareous sediments mainly differs owing to grain-size distribution which control the particles reorganization.• 351, cours de la Libération, 33405 Talence. 50N° 57 REVUE FRANÇAISE DE GÉOTECHNIÛUE

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“…Figure 5 shows that the densities of sediment in the shallow are larger than that of the deep area. Because the density is related with median particle diameter: the density increases with the increase of median particle diameter [22]. According to the sedimentary differentiation, the coarse-grained sediment or heavy particles settle down at first, in the shallow area, and fine-grained sediment or light ones will deposit in the distance, in the deep area.…”

Section: Wet Bulk Densitymentioning

confidence: 99%

Seafloor Sediment Study from South China Sea: Acoustic & Physical Property Relationship

et al. 2015

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Seafloor sediments of different geographical areas in the southern South China Sea (continental shelf, continental slope, and Okinawa Trough) were gravity cored at 21 locations. Sound velocities (V) of the samples were measured at 15-cm increments immediately upon retrieval, and porosity, wet bulk density, and mean grain size were measured later in the laboratory. Empirical equations from previous studies were applied to predict V of sediment samples from the measured physical properties and it was found that the sound velocities derived from the existing equations did not closely match the measured sound velocities. Therefore empirical equations were reconstructed based on the measured data that represent the relationships between physical and acoustic properties of the different geographical area in the study area. Possible explanations for the discrepancies between the measured data and those of previous studies were investigated and found that physical properties, sediment types, geographical area, etc. are important factors that influence sound velocity. The empirical equations of this report should be preferred for prediction of sediment sound velocity for high-frequency acoustic experiments.

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Acoustic and physical property relationships in marine sediment

Cited by 72 publications

References 0 publications

Predicting the Impact of Seabed Uncertainty and Variability on Propagation Uncertainty

Predicting the Impact of Seabed Uncertainty and Variability on Propagation Uncertainty

Vitesse du son dans les sédiments marins durant les premiers stades du tassement

Seafloor Sediment Study from South China Sea: Acoustic & Physical Property Relationship

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