Drilled Shaft Axial Design Values: Predicted Versus Measured Response in a Calcareous Clay

Camp, William M.; Mayne, Paul W.; Brown, Dan

doi:10.1061/40601(256)108

Cited by 11 publications

(5 citation statements)

References 8 publications

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“…Data from a nearby site in the same Cooper Marl but at a shallow depth (less than 9 m) have higher values of Q tn > 40 and plot more in the SC and SD regions and with values of U 2 as high as 50. The high K G * and U 2 values indicate significant microstructure consistent with cementation from the high carbonate content (Camp et al 2002). The high Q tn values suggest a relatively high apparent OCR (>4) and possible dilative behaviour, whereas the high U 2 values show a more contractive behaviour at high shear strains consistent with a cemented soil.…”

Section: Soils With Significant Microstructurementioning

confidence: 72%

“…Figure 15 shows SCPTu data to a depth of 50 m at the Cooper River Bridge site in Charleston, South Carolina (Camp et al 2002), where the soil below a depth of 22 m is Cooper Marl, which is a stiff calcareous plastic clay or silt of Eocene to Oligocene age (ϳ30-40 million years ago). The SCPTu data from 22 to 50 m plot predominately in the transitional-contractive (TC) region of the Q tn -F r chart and the claylike-contractive (CC) region of the Q tn -U 2 chart with an average K G * = 580.…”

Section: Soils With Significant Microstructurementioning

confidence: 99%

See 1 more Smart Citation

Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an update

Robertson¹

2016

Can. Geotech. J.

306

237

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A soil classification system is used to group soils according to shared qualities or characteristics based on simple cost-effective tests. The most common soil classification systems used in geotechnical engineering are based on physical (textural) characteristics such as grain size and plasticity. Ideally, geotechnical engineers would also like to classify soils based on behaviour characteristics that have a strong link to fundamental in situ behaviour. However, existing textural-based classification systems have a weak link to in situ behaviour, since they are measured on disturbed and remolded samples. The cone penetration test (CPT) has been gaining in popularity for site investigations due to the cost-effective, rapid, continuous, and reliable measurements. The most common CPT-based classification systems are based on behaviour characteristics and are often referred to as a soil behaviour type (SBT) classification. However, some confusion exists, since most CPT-based SBT classification systems use textural-based descriptions, such as sand and clay. This paper presents an update of popular CPT-based SBT classification systems to use behaviour-based descriptions. The update includes a method to identify the existence of microstructure in soils, and examples are used to illustrate the advantages and limitations of such a system.Key words: cone penetration test (CPT), soil classification, microstructure, case histories.Résumé : Un système de classification des sols est utilisé pour grouper des sols selon les qualités partagées ou les caractéristiques basées sur des essais efficaces peu coûteux. Les systèmes de classification de sol les plus courants utilisés en génie géotechnique sont basés sur des caractéristiques physiques (textures) tels que la taille des grains et la plasticité. Idéalement, les ingénieurs géotechniques tiennent également à classer les sols en fonction des caractéristiques comportementales qui ont un lien étroit aux comportements fondamentaux in situ. Cependant, les systèmes existants de classification basés sur la texture ont un maillon faible au comportement in situ, car ils sont mesurés sur des échantillons perturbés et remaniés. Les essais faits au moyen de pénétration au cône (« cone penetration test » CPT) ont gagné en popularité pour les études de sites en raison des mesures rentables, rapides, continues et fiables. Les systèmes de classification basée sur le CPT les plus courants sont basés sur les caractéristiques du comportement et sont souvent appelés une classification de type de comportement de sol (« soil behaviour type » SBT). Toutefois, une certaine confusion existe puisque la plupart de systèmes de classification SBT basés sur le CPT utilisent des descriptions axées sur la texture, comme le sable et l'argile. Cet article présente une mise à jour des systèmes populaires de classification SBT basés sur le CPT, afin d'utiliser les descriptions basées sur le comportement. La mise à jour inclut une méthode pour identifier l'existence de microstructures dans les sols et ...

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Section: Soils With Significant Microstructurementioning

confidence: 72%

Section: Soils With Significant Microstructurementioning

confidence: 99%

Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an update

Robertson¹

2016

Can. Geotech. J.

306

237

View full text Add to dashboard Cite

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“…Many series of undrained triaxial compression (CIUC) tests with porewater pressure measurements were performed on the Cooper Marl by several consulting groups and testing firms, with over 100 triaxial tests completed. Results indicate that generally ranges from 40°to 46°with a mean = 43° (Camp et al 2002a(Camp et al , 2002b. The calcareous clay studied at the Arthur Ravenel Bridge site has a mean Fig.…”

Section: Cooper Marl Charleston South Carolinamentioning

confidence: 96%

Effective friction angle of clays and silts from piezocone penetration tests

Ouyang

Mayne

2018

Can. Geotech. J.

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An existing effective stress limit plasticity solution for piezocone penetration tests (CPTu) is calibrated to evaluate the effective stress friction angle ([Formula: see text]) for undrained conditions for a variety of fine-grained soils ranging from natural lean to plastic clays and clayey silts from marine, alluvial, lacustrine, deltaic, and glaciofluvial origins. Data from 105 clay sites are compiled to examine the CPTu-interpreted [Formula: see text] values in comparison with laboratory benchmark values obtained from undrained consolidated anisotropic (CAUC) and undrained compression (CIUC) triaxial tests made on undisturbed samples. An approximate inversion of the theoretical solution is developed to allow profiles of [Formula: see text] to be evaluated with depth. Five well-documented case studies in Illinois, Louisiana, South Carolina, Ireland, and Massachusetts are presented to illustrate the application of the solution. Lastly, results from 1g chamber tests involving kaolin and kaolinitic–silica mixtures tested by miniature piezocone probes are shown for additional verification.

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“…This material appears as a sandy calcareous clay of Oligocene age, with a very high calcium carbonate content between 60 to 80% (Camp, et al 2002). This material appears as a sandy calcareous clay of Oligocene age, with a very high calcium carbonate content between 60 to 80% (Camp, et al 2002).…”

Section: Case Study Applications In Claysmentioning

confidence: 97%

In-situ test calibrations for evaluating soil parameters

Mayne¹

2006

Characterisation and Engineering Properties of Natural Soils

116

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The interpretation of in-situ geotechnical test data needs a unified approach so that soil parameters are evaluated in a consistent and complementary manner with laboratory results. A common thread in assessing in-situ tests is the focus on the geologic stress history, often expressed by the overconsolidation ratio (OCR). For clays, the OCR can be measured by consolidation tests on undisturbed samples, yet for sands is rather problematic to address. For 6 clays, a hybrid cavity expansion -critical state model is used to match responses measured CPT, CPTu, and DMT. Specifically, tip stress, sleeve friction, penetration porewater pressures, and flat dilatometer readings are fitted by parametric input of OCR, void ratio, friction angle, rigidity index, and compressibility parameters. The undrained shear strength (s u ) of clays is best handled via critical-state concepts. Discussions are included for pressuremeter, vane, and T-bar tests. For sands, select empirical methods derived from laboratory chamber testing on reconstituted clean quartz and siliceous sands are reviewed, specifically for effective friction angle φ , OCR, and K 0 . In a novel look, a special set of undisturbed (frozen) sand samples from 15 locations in Japan, Canada, Italy, Norway, and China is used to check interrelationships for the following in-situ penetration tests: SPT, CPT, and V s . Stiffness of all soils begins with the small-strain shear modulus (G 0 = G max = ρ T V 2 s ) that can be used together with strength (s u or φ ) to evaluate stiffness over a range of strains. Supplementary testing by PMT and/or DMT can provide intermediate stiffnesses for tuning of modulus reduction schemes, as well as independent assessments of K 0 and OCR.

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Drilled Shaft Axial Design Values: Predicted Versus Measured Response in a Calcareous Clay

Cited by 11 publications

References 8 publications

Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an update

Cone penetration test (CPT)-based soil behaviour type (SBT) classification system — an update

Effective friction angle of clays and silts from piezocone penetration tests

In-situ test calibrations for evaluating soil parameters

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