Effects of sampler design on tube sampling disturbance—numerical and analytical investigations

Clayton, C. R. I.; Siddique, Abu Bakr; Hopper, R.J.

doi:10.1680/geot.1998.48.6.847

Cited by 62 publications

(34 citation statements)

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“…As discussed by Clayton et al (1998), numerous researchers have investigated the extent and nature of disturbance during sampling and laboratory testing (Skempton and Sowa, 1963 Lau, 1988; Clayton et al, 1992). However, most of this research has been focused on comparative experimental investigations.…”

Section: Introductionmentioning

confidence: 99%

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Shear wave Velocities for Sample Quality Assessment on a Residual Soil

Ferreira

Fonseca

Nash

2011

Soils and Foundations

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For the assessment of the quality of laboratory samples, a number of methods are available, though not universally applicable to any soils. This paper examines the issue of sampling quality and its assessment using comparisons between shear wave velocity measurements in situ and in recovered samples as the base, which is very useful in naturally structured granular soils, like residual soils. For this purpose, cross-hole and down-hole tests were performed in thê eld and bender elements measurements were made on triaxial samples collected from two experimental sites on residual soil from Porto granite. Various sampling techniques and tools were used, including block sampling and diŠerent tube samplers. The analysis of the results has led to a new classiˆcation of sampling quality and sample condition based on the comparison of normalised shear wave velocities in theˆeld and in the laboratory.

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Section: Introductionmentioning

confidence: 99%

“…This method was further extended by Clayton et al (1998) to examine the eŠects of diŠerent details of sampling tube geometry, including outside cutting edge angle (OCA), inside cutting edge angle (ICA), inside clearance ratio (ICR) and area ratio (AR), as deˆned in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

Shear wave Velocities for Sample Quality Assessment on a Residual Soil

Ferreira

Fonseca

Nash

2011

Soils and Foundations

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“…Three deformation stages were identified for soil located at the centreline of the sampler: (a) compression, ahead of the sampler, (b) extension, near to the cutting edge, and (c) compression, inside the sampler. Clayton et al [8] complemented the work done by Baligh and co-workers by considering more realistic geometries for the cutting edge of the sampler. The results were analyzed in terms of the geometric descriptors introduced by Hvorslev [27] to quantify the effects of tube sampling caused by different tools.…”

Section: Block Samplingmentioning

confidence: 99%

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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“…Ladd and Lambe 1963;Baligh 1985;Baligh et al 1987;Hight et al 1992;Tanaka et al 1996;Lunne et al 1997;Clayton et al 1998;Hight 2001;Ladd and DeGroot 2003). This modifies the mechanical characteristics of the soil and leads to the specification of different, and in general more conservative, material parameters (e.g.…”

Section: Introductionmentioning

confidence: 99%

Economic Sampling and Extraction of Undisturbed, High Quality Samples in Normally Consolidated Lacustrine Clays Using a Large Diameter Tube

Messerklinger

Springman

2008

Geotech Geol Eng

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This paper describes the development, design and use of a large diameter sampling tube. High quality test specimens are essential for the investigation of mechanical properties of a soil for high risk projects and when complex and expensive testing methods are to be used. Block sampling is recommended to give the highest sample quality for clayey soils, however, extracting blocks of normally consolidated lacustrine silty clay without excessive disturbance was challenging due to the inherent structure of the soft varved silty clay and difficulty in maintaining K o conditions, as well as no vertical strain, in the sample. A new sample tube, with an inner diameter of 196 mm, an area ratio of 4% and an outer cutting-edge angle of 11°was designed to offer a larger cross sectional area than conventional thin walled sampling tubes, to provide the necessary side support and to prevent water ingress at the sides of the sample. The length-diameter aspect ratio was 1.275 to optimise the amount of clay sampled for subsequent testing and in an attempt to minimize the pressure in front of the tube. Samples were taken in initially newly excavated trenches at a depth of c. 1 m with this new sampler and with conventionally sampled soil specimens, prior to the main testing programme with samples from 6 m depth. A comparative study was then performed including preliminary unconsolidated unconfined compression tests followed by anisotropically consolidated undrained triaxial compression tests. It was important to establish whether this approach had led to an improvement in sample quality prior to embarking on an extensive triaxial stress path testing programme on this varved soil (Messerklinger, Non-linearity and small strain behaviour in lacustrine clay, 2006; Messerklinger and Springman, Geotech Test J 30(6), 2007; Messerklinger and Springman, Geotech Geol J, 2008). The results showed that the undrained shear strength of the specimens from the new sampler was consistently around 20% higher than that of specimens extruded from conventional thin walled tube samplers. This confirmed that samples with a significantly higher quality could be extracted from normally consolidated, fine grained, varved lacustrine deposits with this large diameter 'block' sampling tube.

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Effects of sampler design on tube sampling disturbance—numerical and analytical investigations

Cited by 62 publications

References 0 publications

Shear wave Velocities for Sample Quality Assessment on a Residual Soil

Shear wave Velocities for Sample Quality Assessment on a Residual Soil

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

Economic Sampling and Extraction of Undisturbed, High Quality Samples in Normally Consolidated Lacustrine Clays Using a Large Diameter Tube

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