Soil deformation around a penetrating cone in silt

Paniagua, Priscilla; Andò, Edward; Silva, M.; Emdal, Arnfinn; Nordal, Steinar; Viggiani, Gioacchino

doi:10.1680/geolett.13.00067

Cited by 37 publications

(26 citation statements)

References 11 publications

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“…In these plots, r c is the cone radius, r is the distance measured from the intersecting point between the vertical cone axis and the horizontal shoulder axis, x is the horizontal distance from the cone vertical axis. Lower void ratio values can be observed near the cone face for r/ r c \ 1.75, which coincides with the limits of the contraction zone identified by Paniagua et al [27]. Beyond this point, the void ratio values are in general greater which suggests the presence of a dilation region.…”

Section: Resultssupporting

confidence: 87%

“…15a. Figure 15b, c, d provides a comparison of the compressive and dilative zones observed by Paniagua et al [27] with the values of void ratio and anisotropy extracted from the fabric tensor analysis. One can see that the limit between the compaction and dilative zone is near a void ratio value of 1.0 and anisotropy value of 0.15 for flaky grains and 0.05 for bulky grains, respectively.…”

Section: Behavior Across the Scalesmentioning

confidence: 95%

“…The paddings were used to compensate for the effect of the boundary closeness and account for the compressibility of the surrounding soil. The thickness and padding stiffness values were obtained from finite element (FE) calculations of an expanding cavity in silt with a cavity diameter equal to the sample diameter (more details can be found in Paniagua et al [27].…”

Section: Test Set-up and Equipmentmentioning

confidence: 99%

“…4. The areas are distributed according to the deformation zones observed by Paniagua et al [27] and termed with the name of the test followed by the location, e.g., sample MMT01-S1-1 is from test MMT01 and from region 1-1 around the shaft (S). The EPMA images representing each area have a size of 854 by 896 pixels.…”

Section: Microscopy Equipmentmentioning

confidence: 99%

“…According to these studies, silts with high percentage of fines will tend to have a dominant contractive behavior, which can be linked to the fact that those samples also exhibit higher density. Paniagua et al [27] have shown that both contractive and dilative behavior can actually coexist in the same specimen. The authors have carried out laboratory scale CPT tests on Vassfjellet silt and using X-ray micro-CT together with volumetric digital image correlation (3D-DIC) analyses have shown the formation of two distinct bulb-shaped zones under the tip of the cone: a compaction and a dilation zones, respectively (Fig.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of the change in soil fabric during cone penetration in silt using 2D measurements

et al. 2017

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Interpretation of CPTU testing in silt is nontrivial because of the partially drained conditions that are likely to occur during penetration. A better understanding of the pore pressure generation/dissipation is needed in order to obtain reliable design parameters. Following a previous study using X-ray computed tomography (micro-CT) with volumetric digital image correlation (3D-DIC) that clearly showed the formation of distinct dilation and compression areas around the cone; the present work takes a closer look at those areas in order to link volumetric behavior to changes in soil fabric. High-resolution 2D backscattered electron images of polished thin sections prepared from frozen samples at the end of penetration are used. The images have a spatial resolution of 0.4 lm/pixel that allow a clear identification of grains and pore spaces. Image processing techniques are developed to quantify local porosity and obtain the statistical distribution of the particle orientation for the zones around the cone tip and shaft. It is shown that the formation of compaction regions is related to the ability of the grains to rearrange and align along a well-defined preferred orientation forming a more closed-fabric characterized by high anisotropy values, while zones of dilation are associated with a more open packing with grains randomly oriented and with large voids within. These observations suggested that for a saturated soil, water will move from a compressive zone to a neighboring dilative zone, creating a short drainage path. By shedding light on the link between soil fabric and drainage patterns, this study contributes toward a better understanding of the measured macro-response during CPTU tests on silt.

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Section: Resultssupporting

confidence: 87%

Section: Behavior Across the Scalesmentioning

confidence: 95%

Section: Test Set-up and Equipmentmentioning

confidence: 99%

Section: Microscopy Equipmentmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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