Advanced laboratory testing in research and practice: the 2nd Bishop Lecture

Jardine, Richard J.

doi:10.1680/geores.14.00003

Cited by 22 publications

(10 citation statements)

References 49 publications

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“…1. Elastic -Cyclic stress remains within the small Y 1 region, as described for example by Jardine (2014). This region behaviour could not be resolved unambiguously within the present experiments.…”

Section: Clay Response and Shakedown Behaviourcontrasting

confidence: 61%

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Undrained behaviour of intact soft clay under cyclic paths that match vehicle loading conditions

et al. 2018

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4Vehicle traffic loading appears to contribute significantly to long term settlement beneath highways, airport runways 5 and metro lines in China. Wheel loading imposes cycles in both the magnitude and direction of the principal stresses acting 6 on the soils beneath pavement or rail-track structures. Conventional cyclic triaxial testing, which is not capable of imposing 7 such stress paths may underestimate how heavy traffic loading affects any underlying soft clay layers. Hollow cylinder 8 apparatus (HCA) can simulate such traffic loading stress paths more accurately, including rotation of the principal stress 9directions. This paper presents a systematic experimental study of cyclic HCA (CHCA) tests on K 0 -consolidated saturated 10 soft clay involving cyclic variations in both vertical and torsional shear stresses, along with a parallel programme of cyclic 11 triaxial (CT) tests, considering the undrained response of saturated samples of intact soft clay. It is shown that when 12 applied above certain critical cyclic stress ratios, principal stress rotation accelerates excess pore water pressure and 13 permanent strain development. Corresponding changes are also seen in the resilient modulus and damping ratio trends. 14 The discrepancies between the behaviour of CHCA and equivalent cyclic triaxial tests grow as the cyclic stress ratios 15 increase. 16

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Section: Clay Response and Shakedown Behaviourcontrasting

confidence: 61%

“…2. Elastic shakedown -Higher levels of cyclic loading lead to the specimen undergoing Y 1 yielding first, but remaining within the Y 2 kinematic yield surface reported by Jardine (2014) and exhibiting slight plastic deformation such as that seen up to the CSR ≥ 0.03 limit. 3.…”

Section: Clay Response and Shakedown Behaviourmentioning

confidence: 77%

Undrained behaviour of intact soft clay under cyclic paths that match vehicle loading conditions

et al. 2018

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“…Following earlier geophysical and triaxial stiffness studies of the Gault and Oxford clays by Butcher & Lord (1993), Butcher & Powell (1995), Hird & Pierpoint (1997), Pennington et al (1997) and Ng et al (1998), the new work allows direct comparisons to be made between the stiffness properties of the four Jurassic-toEocene clays, which are reported within the framework set out below. Arup (2007) (2) Pierpoint (1996) 100 mm UU (1) Framework for test interpretation Jardine (1992Jardine ( , 2013 emphasises that behaviour can only be considered elastic within a very small area of the permissible stress space that is limited by a kinematic hardening (Y 1 ) true yield surface. The latter is dragged with the current effective stress point, growing and shrinking with p′ and changing in shape with proximity to the outer Y 3 surface, which corresponds to the yield surface recognised in classical critical state soil mechanics.…”

Section: Discussionmentioning

confidence: 99%

The shear stiffness characteristics of four Eocene-to-Jurassic UK stiff clays

et al. 2017

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A large proportion of the southern UK is underlain by stiff clays. Improving their geotechnical characterisation is important for many current and future infrastructure projects. This paper presents an integrated study of the complex stiffness behaviour of four key medium-plasticity, highly overconsolidated strata: the Gault, Kimmeridge, Oxford and London clays. The latter were deposited between the Jurassic and the Eocene under broadly similar marine conditions. Coordinated programmes of advanced static and dynamic laboratory measurements have been undertaken on high-quality samples, concentrating on samples taken from similar depths at inland sites and including triaxial and hollow cylinder stress path experiments employing high-resolution local strain, multi-axial bender element and resonant column techniques. A new approach was employed to interpret the hollow cylinder experiments and the laboratory measurements are examined in combination with independent field shear wave data. The clays' stiffness characteristics are shown to be markedly anisotropic, pressure dependent and highly non-linear. Synthesis allows key conclusions to be drawn regarding: the relative reliability of alternative measurement approaches; the potential spread of stiffness behaviours between the clays; and whether the clays' varying geological ages and burial depths have any systematic influence on their stiffness characteristics. The results have important geotechnical engineering implications.

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“…Axial capacity predictions are crucial to many applications, especially those involving offshore tension leg, tripod or jacket structures (e.g. Overy, 2007;Merritt et al, 2012;Jardine, 2013). Foundation stiffness can also be important to both structural fatigue life and wind turbine operations.…”

Section: Introductionmentioning

confidence: 99%

A new and openly accessible database of tests on piles driven in sands

Yang

Jardine

Guo³

et al. 2015

Géotechnique Letters

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This paper reviews the critical need to develop better load test databases for piles driven in sand before reporting on the significantly augmented, openly accessible, Zhejiang University/Imperial College London (ZJU-ICL) database. Key quality parameters, the population of current entries and the reporting format are described before offering preliminary results obtained from comparisons between axial capacities calculated by various predictive approaches and site measurements. The results confirm that the offshore industry-standard 'Main Text' American Petroleum Institute RP2GEO procedures are less reliable and have larger coefficients of variation than alternative cone penetration test (CPT) methods, among which the ICP (Imperial College piles) and UWA (University of Western Australia) procedures appear to give the least bias and scatter. It is also shown that the 'simplified' ICP variant proposed by some practitioners is over-conservative and that its use could be discontinued. The new pile capacity and stiffness database offers broad scope for evaluating potential prediction biases relating to a wide range of soil and pile parameters. The submission of further high-quality tests for inclusion in regularly updated versions of the ZJU-ICL database is encouraged.

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Advanced laboratory testing in research and practice: the 2nd Bishop Lecture

Abstract: NotationCc gradient in oedometer e-log z σ ¢ relationship Cu coefficient of uniformity = d90/d10 D diameter; Dchamber and Dpile are the calibration chamber and pile diameters, respectively d10, d50, d90 particle diameters at 10%, 50% and 90% points, respectively, on particle-

Cited by 22 publications

References 49 publications

Undrained behaviour of intact soft clay under cyclic paths that match vehicle loading conditions

Undrained behaviour of intact soft clay under cyclic paths that match vehicle loading conditions

The shear stiffness characteristics of four Eocene-to-Jurassic UK stiff clays

A new and openly accessible database of tests on piles driven in sands

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