Carbonate Content: An Index Property for Ocean Sediments

Demars, Kenneth R.; Nacci, V.A.; Kelly, William E.; Wang, M.C.

doi:10.4043/2627-ms

Cited by 19 publications

(11 citation statements)

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“…Obviously, this apparent overconsolidation effect due to carbonate cementation was responsible for insignificant settlement during the period beyond 1991. Such low values were reported earlier by Demars et al (1976). …”

Section: Pore Pressure Parametersupporting

confidence: 76%

Strength Behavior of Naturally Cemented Marine Clay Due to Change in Ground Water Level

Moses

Rao

2008

Marine Georesources & Geotechnology

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The change in strength and deformation behavior of a typical marine clay deposit formed under shallow water is presented and discussed for the conditions of changing water table. This is a costal marine clay deposit with moderate carbonates along the east coast of India. The soil samples were taken from tidal flats where the sea had receded some time back, and the behavior of this deposit had been studied for the conditions of 1976, with high water table, and for the conditions of 2001, with depleted water table. Undisturbed soil samples were taken from sheeted open test pits. Standard consolidation and triaxial shear tests were conducted. Consolidation tests conducted on the samples taken for 1976 conditions with high water contents indicate that cementation effect are erased out under moderate stresses. Beyond this stress range, it behaves like soft, normally consolidated clay. In contrast, the results obtained from samples taken during 2001, with depleted water table, clearly indicate that the soil behaves like an over-consolidated one, and the improvement in the system is due to the chemical bonding and desiccation.

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Section: Pore Pressure Parametersupporting

confidence: 76%

Strength Behavior of Naturally Cemented Marine Clay Due to Change in Ground Water Level

Moses

Rao

2008

Marine Georesources & Geotechnology

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“…Carbonate content of deep-ocean soils also appears to effect the <£' value. Demars et al (1976) found that <£' values increased from about 28° to 31° when carbonate content increased from around 25% to more than 60%.…”

Section: Sediment Strengthmentioning

confidence: 95%

“…These values probably indicate the presence of a substantial amount of highly plastic clay minerals, such as montmorillonite, among the skeletal Downloaded by [University of Calgary] at 15:55 30 March 2015 debris, rather than plasticity inherent in the pure ooze. Demars et al (1976) found that, for calcareous oozes obtained from the eastern portion of the Atlantic Ocean, specimens with carbonate contents greater than 40% exhibit granular behavior, and specimens with carbonate content less than 40% exhibit cohesive behavior. Keller and Bennett (1973) carried out Atterberg limit tests on calcareous ooze samples from DSDP sites 158, 160, 161, and 162 with a resulting spread of plasticity values similar to those indicated for calcareous oozes in Figure 2.…”

Section: Sediment Plasticity and Mineralogymentioning

confidence: 97%

“…Valent's conclusions should be equally applicable to siliceous oozes. Recently, Demars et al (1976) proposed a relationship between C c and the plasticity index for calcareous oozes, based on the results of more than 30 consolidation tests. Lee (1973c) proposed a correlation for C e , water content, and void ratio of diatom oozes, but notes that this correlation is probably only valid for siliceous soils.…”

Section: Consolidation Characteristicsmentioning

confidence: 99%

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Geotechnical properties of deep continental margin soils

Davie

Fenske

Serocki³

1978

Marine Geotechnology

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The engineering properties of deep continental margin sediments were determined on a worldwide basis. Deep Sea Drilling Project (DSDP) core data and material were utilized from over 900 cores obtained from 89 sites, primarily on the continental margins. Cores were recovered from penetrations to 200 m in water depths averaging 3000 m. Supplementary laboratory testing on selected cores was directed toward determining index properties and shear strength properties of the sediments. The study included a literature review of deep-sea soil properties, the results of which are to be used by DSDP to evaluate foundation conditions for reentry cones with long casing strings. The results will also be used for a feasibility study of an ultradeepwater marine riser and wellcontrol system. The marine sediments examined can be divided into three main types: clay, calcareous ooze, and siliceous ooze. Sediment distribution consisted of 48% calcareous ooze, 43% clay, 6% siliceous ooze, and 3% volcanic ash. Because of the sample disturbance inherent in the deepwater coring operation, emphasis was placed on analyzing sediment properties not significantly affected by changes in in situ stresses and structure caused by sampling. Averages and ranges in values of water content and unit weight are presented for the three main sediment types. Plasticity and strength characteristics are discussed in detail and the elastic and compression properties are outlined. The geotechnical properties of deep continental margin soils are summarized.

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“…Several researchers (e.g. Demars et al 1976;Agarwal et al 1977) have identified parameters that affect the engineering behaviour of calcareous soils (e.g. carbonate content, crushability, degree of cementation and index properties).…”

Section: Introductionmentioning

confidence: 99%

Laboratory investigations to assess the feasibility of employing a novel mixed-in-place offshore pile in calcareous deposits

Doherty

Spagnoli

Doherty

2015

Ships and Offshore Structures

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Calcareous sands are typical of warmer seas and are encountered in several high growth locations around the world. Despite having high frictional resistance with friction angles exceeding those of siliceous sands, the in situ behaviour is characterised by particle damage and extreme contraction at high confining stresses. This behaviour results in very low values of skin friction for driven piles in calcareous deposits, where the contraction dominates the pile response. The MIxed Drilled Offshore Steel (MIDOS) pile is a novel mixed-in-place technology which has many advantages over driven steel piles and conventional drilled-and-grouted (D&G) piles. The MIDOS is based on the deep-mixing technology normally used as an onshore ground improvement technique. The mechanical technology and in situ pile performance were successfully demonstrated during an in situ test in silica sand. A laboratory based study was undertaken to assess the MIDOS performance in calcareous sand. Geotechnical tests, grout tests and steel-grout pull out tests were performed to assess the sands and to model the behaviour at the interface of the steel reinforcement and the grout body. These preliminary results demonstrate that the frictional shaft resistance at the pile-soil interface is comparable for both silica and calcareous sands, and as there is no stress relief or contraction during the installation process, the geotechnical performance of the MIDOS pile is deemed comparable for both soil types tested.

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Carbonate Content: An Index Property for Ocean Sediments

Cited by 19 publications

References 0 publications

Strength Behavior of Naturally Cemented Marine Clay Due to Change in Ground Water Level

Strength Behavior of Naturally Cemented Marine Clay Due to Change in Ground Water Level

Geotechnical properties of deep continental margin soils

Laboratory investigations to assess the feasibility of employing a novel mixed-in-place offshore pile in calcareous deposits

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