Site characterisation for the Ballina field testing facility

Kelly, Richard; Pineda, Jubert; Bates, Lucy; Suwal, S. P.; Fitzallen, A.; Mesri, G.; Kane, Thierno

doi:10.1680/jgeot.17.d.011

Cited by 8 publications

(16 citation statements)

References 19 publications

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“…We further show that the standard Tresca failure criterion, albeit simplistic, will provide reasonable estimates of the mobilised strength if properly calibrated against field vane tests. (Kelly et al 2017;Pineda et al 2016). Among these data of particular interest for stability analysis is the significant D r a f t 3 variation of the undrained shear strength of the soft, structured Ballina clay with the mode of shearing ( Fig.…”

Section: Interpretation Of Vane Shear Tests For Geotechnical Stabilitmentioning

confidence: 99%

Interpretation of vane shear tests for geotechnical stability calculations

et al. 2017

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In this note we consider the problem of calibrating failure criteria for short-term stability calculations based on the results of vane shear tests. Numerical and theoretical considerations supported by experimental data provide evidence that we can use the vane shear test to obtain the undrained strength of a sample tested under simple shear conditions at a normal stress equal to the horizontal effective stress at the given depth. Consequently, it is argued that there is no need to correct the field vane undrained strength to obtain the mobilized strength for embankment stability calculations, provided that soil strength is normalized to the normal effective stress acting on the slip surface and rate effects are properly considered. We further show that the standard Tresca failure criterion, albeit simplistic, will provide reasonable estimates of the mobilized strength if properly calibrated against field vane tests.

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Section: Interpretation Of Vane Shear Tests For Geotechnical Stabilitmentioning

confidence: 99%

Interpretation of vane shear tests for geotechnical stability calculations

et al. 2017

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“…The establishment by the ARC Centre of Excellence for Geotechnical Science and Engineering (CGSE) of a National Soft Soil Testing Facility (NFTF) at Ballina, New South Wales, [34] has allowed high-quality in situ testing and monitoring, combined with advanced laboratory testing, to characterize a typical Australian estuarine soft clay with the goal of improving engineering design methods. The stratigraphy at Ballina site comprises the alluvial crust (z \ 1.5 m) which is underlain by the Ballina clay (1.5 \ z \ 11 m), a transition zone with increasing sand content, sand (11 \ z \ 14 m), and stiff clay (z [ 15 m).…”

Section: Deltaic Deposits From Castelló D'empuries (Costa Brava Spain)mentioning

confidence: 99%

“…The block specimen was covered with several layers [58]. b, c CPTu profiles from the estuarine deposits at Ballina site [34] of plastic wrap and foil seal to avoid moisture losses. A PVC tube (400 mm in diameter) was used to protect the sample laterally.…”

Section: Block Samplingmentioning

confidence: 99%

“…Figure 32 shows the vertical sections of two tube specimens, retrieved from two near-by boreholes at the Ballina field testing facility [34] using an Osterberg fixed piston sampler (Fig. 32a) and a Shelby tube (Fig.…”

Section: Image Analysismentioning

confidence: 99%

“…Three tube specimens were tested. They were retrieved at the Ballina field testing facility [34] The sampler types were selected to include the most common ones used in practice (Shelby tubes) as well as the 'most adequate' (fixed piston) sampler commercially available for soft soils. The samplers have ratios B/t (external diameter to wall thickness) ranging between 31 and 49 ( Table 4).…”

Section: Microstructural Analysismentioning

confidence: 99%

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Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Fonseca

Pineda

2017

Innov. Infrastruct. Solut.

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Laboratory tests are well recognized as highly appropriate for defining the engineering properties of geomaterials, in terms of constitutive law parameters for modeling geotechnical engineering problems. The strong development of advanced techniques, both in equipment and in data interpretation, has increased the confidence in laboratory testing, while on the other hand the limitations due to the quality of soil sampling with depth and the spatial representativeness of the samples are less consensual. Still, the development of new methods for assuring high-quality samples is increasing, together with sampling quality assessment by non-destructive methods using vibration wave velocities. Interpretation methods of in situ tests for ground characterization have also evolved significantly, increasing the reliability of these methods. Their versatility to cover large areas on site and the fact that these tests are, in principle, performed at the actual state (physical and stress) conditions, as well as the improvements in the correlations between field tests and hydraulic and geomechanical parameters, allow joining the quality of data and theoretical approaches, namely through critical state soil mechanics. This keynote paper discusses some of the aspects that can and should enable the association of ground characterization from laboratory testing over undisturbed samples used in more or less advanced tests, enhancing the determinant conditioning factor, that is, the sampling technique to get representative specimens and the way this is assessed. The confidence that we expect to have on the geomechanical parameters that we need for our geotechnical activities will mostly depend on this in view of the high uncertainties of the parametrical correlations with in situ test data, therefore, important in ground characterization. This is especially relevant in sensitive soils, such as soft fine soils, loose sandy soils, or young residuals soils. These have or can have ''weak'' equilibria of the interparticle micro-and macrostructures (or their arrangement, fabric) that will change substantially their properties if samples are collected and conditioned with processes that do not preserve that intrinsic ''ADN''. The change in these natural conditions can be evaluated by techniques of quality assessment, which will be discussed in what follows.

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Predicted and measured behaviour of an embankment on PVD-improved Ballina clay

Lim

Pineda

Boukpeti

et al. 2018

Computers and Geotechnics

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This paper presents Class-A and Class-C predictions of the behaviour of an embankment built on soft Ballina clay improved with prefabricated vertical drains. Predictions were carried out using hand calculations and the finite-difference method. The latter approach allowed the variation of soil parameters and stress levels with depth to be considered in the analyses. An alternative systematic procedure for estimating soil parameters based on high-quality laboratory data is described. Class-A predictions highlighted some disagreement with the measured total settlements and pore pressure dissipation rates. For Class-C predictions, the choice of geotechnical parameters used in the analyses was guided by a systematic assessment of the stress states undergone by soil elements underneath the embankment centreline. This led to a better agreement between predicted and measured data, which demonstrates the potential of the proposed procedure for future analyses of embankment behaviour on soft Ballina clay

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Site characterisation for the Ballina field testing facility

Cited by 8 publications

References 19 publications

Interpretation of vane shear tests for geotechnical stability calculations

Interpretation of vane shear tests for geotechnical stability calculations

Getting high-quality samples in ‘sensitive’ soils for advanced laboratory tests

Predicted and measured behaviour of an embankment on PVD-improved Ballina clay

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