Performance of cyclic cone penetration tests in chalk

Diambra, Andrea; Ciavaglia, Francesca; Harman, Alistar; Dimelow, Chris; Carey, John; Nash, Dft

doi:10.1680/geolett.14.00050

Cited by 21 publications

(7 citation statements)

References 3 publications

(3 reference statements)

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“…Fugro, 2012b) and the performance of two cyclic CPTs (Diambra et al, 2014). Two typical CPT profiles 45 in the vicinity of the two tested piles are reported in Figure 1.…”

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confidence: 98%

Time-dependent uplift capacity of driven piles in low to medium density chalk

Ciavaglia¹,

Carey²,

Diambra

2017

Géotechnique Letters

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A series of load tests have been performed on instrumented 762 mm dia. tubular steel piles driven into low to medium density grade A/B chalk at St Nicholas at Wade, Kent, UK. This paper presents the results from the static axial uplift tests, which were performed on two piles 7, 50 and 120 days after installation in order to investigate the time-dependent variations in shaft resistance. The results show that the static ultimate shaft resistance of this type of chalk can increase by up to a factor of seven over this time period, as a consequence of ‘set-up’ effects. The test results also show that the ‘set-up’ effect is reduced if the pile is subject to lateral loads up to 50% of the ultimate lateral capacity before uplift loading, while the application of lateral loading up to 10% of ultimate lateral capacity had negligible influence on axial capacity. The measured load distribution from strain gauges suggests a mobilisation of larger unit shaft resistance in the lower half of the pile. This paper also describes the geotechnical site conditions, the pile instrumentation and the effects of pile driving on the chalk.

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“…Fugro, 2012b) and the performance of two cyclic CPTs (Diambra et al, 2014). Two typical CPT profiles 45 in the vicinity of the two tested piles are reported in Figure 1.…”

mentioning

confidence: 98%

Time-dependent uplift capacity of driven piles in low to medium density chalk

Ciavaglia¹,

Carey²,

Diambra

2017

Géotechnique Letters

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“…Intact Unconfined Compressive Strength (UCS) tests on saturated samples give ranges from approximately 1.25 to greater than 12.5MPa (Bowden et al 2002) and cone tip resistances, q ୡ from 4 to greater than 50MPa (Power 1982). High porosity chalk is known to degrade rapidly through a puttification mechanism when subjected to percussive pile driving (Hobbs and Atkinson 1993;Lord et al 2002), high amplitude laboratory cyclic simple shear testing (Carrington et al 2011) or cyclic cone penetration tests (Diambra et al 2014). Chalk's sensitivity, which relates to its lightly cemented structure and crushable calcium carbonate particles is thought to be responsible for the remarkably low ultimate unit shaft resistances, indicated for driven piles by the sparse data set of published loading tests.…”

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confidence: 99%

Effective stress regime around a jacked steel pile during installation ageing and load testing in chalk

et al. 2018

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This paper reports experiments with 102 mm diameter closed-ended instrumented Imperial College piles (ICPs) jacked into low- to medium-density chalk at a well-characterized UK test site. The “ICP” instruments allowed the effective stress regime surrounding the pile shaft to be tracked during pile installation, equalization periods of up to 2.5 months, and load testing under static tension and one-way axial cyclic loading. Installation resistances are shown to be dominated by the pile tip loads. Low installation shaft stresses and radial effective stresses were measured that correlated with local cone penetration test (CPT) tip resistances. Marked shaft total stress reductions and steep stress gradients are demonstrated in the vicinity of the pile tip. The local interface shaft effective stress paths developed during static and cyclic loading displayed trends that resemble those seen in comparable tests in sands. Shaft failure followed the Coulomb law and constrained interface dilation was apparent as the pile experienced drained loading to failure, although with a lesser degree of radial expansion than with sands. Radial effective stresses were also found to fall with time after installation, leading to reductions in shaft capacity as proven by subsequent static tension testing. The jacked, closed-ended, piles’ ageing trends contrast sharply with those found with open piles driven at the same site, indicating that ageing is affected by pile tip geometry and (or) installation method.

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“…Bialowas et al [13] and Consoli et al [34] investigated chalk from the same location. In addition, this site was recently used for pile and cone penetration tests as reported by [17,19,20,36,41].…”

Section: Methodsmentioning

confidence: 99%

Strength and stiffness of compacted chalk putty–cement blends

et al. 2021

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Chalk breaks easily when subjected to human action such as mechanical handling, earthworks operations or pile installation. These actions break the cemented structure of chalk, which turns into a degraded material known as putty, with lower strength and stiffness than the intact chalk. The addition of Portland cement can improve the behaviour of chalk putties. Yet, there are no studies determining the tensile strength of chalk putty-cement blends, the initial stiffness evolution during the curing time and other design parameters such as friction angle and cohesion of this material. This paper addresses this knowledge gap and provides an interpretation of new experimental results based on the dimensionless index expressed as the ratio between porosity and volumetric content of cement (g/C iv ) or its exponential modification (g/ C iv a ). This index aids the selection of the amount of cement and density for key design parameters of compacted chalk putty-cement blends required in geotechnical engineering projects such as road foundations and pavements, embankments, and also bored concrete pile foundations.

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Performance of cyclic cone penetration tests in chalk

Cited by 21 publications

References 3 publications

Time-dependent uplift capacity of driven piles in low to medium density chalk

Time-dependent uplift capacity of driven piles in low to medium density chalk

Effective stress regime around a jacked steel pile during installation ageing and load testing in chalk

Strength and stiffness of compacted chalk putty–cement blends

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