Using CAT to obtain density maps in Sherbrooke specimens of silty soils

Sau, Nicolás; Arroyo, Marcos; Perez, N.; Pineda, Jubert

doi:10.1201/b17395-207

Cited by 2 publications

(7 citation statements)

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“…An interesting example has been recently reported by Sau et al [63] who use CAT to obtain density maps in 250 mm in diameter block (Sherbrooke) specimens of silty clay deposits from Castelló d'Empuries (Spain), previously described in this paper. In line with the decrease in image quality with the sample diameter, the analysis of block specimens is clearly more demanding.…”

Section: Image Analysismentioning

confidence: 99%

“…As indicated in this figure, sampling took place in the two soft levels. Soil characterization carried out using Sherbrooke specimens [63] showed that these silty deposits present a fine fraction ranging from 60 to 97%. These materials classify as low-plasticity clays (CL) with clayey fractions ranging between 14 and 29%.…”

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

confidence: 99%

“…The Fig. 33 Ring artifact and background noise in Sherbrooke specimens [63] amount of noise varied from top to bottom of the block. Good results were obtained using substacks, i.e., set of slices grouped according to the level of noise, and, for each substack, define different regions of interest (ROIs), here named segments.…”

Section: Image Analysismentioning

confidence: 99%

“…The Sherbrooke sampler [41] is, to date, the mechanical sampling technique capable to produce specimens of the highest quality in soft soils, including quick clays, sensitive clays, silty clays, silts, and peats (e.g., [25,43,44,59,63]; among others). This technique requires pre-drilling a 400-mm borehole to around 500 mm above the sampling depth.…”

Section: Block Samplingmentioning

confidence: 99%

“…This filter replaces each pixel outlier value with a median of neighboring pixel values. The following parameters were required to apply the rank-median filter [63]:…”

Section: Image 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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Section: Image Analysismentioning

confidence: 99%

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

confidence: 99%

Section: Image Analysismentioning

confidence: 99%

Section: Block Samplingmentioning

confidence: 99%

“…This filter replaces each pixel outlier value with a median of neighboring pixel values. The following parameters were required to apply the rank-median filter [63]:…”

Section: Image Analysismentioning

confidence: 99%

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