Pore space evolution of granular assemblies under shear: an experimental study using X-ray tomography

Roy, Nimisha; Frost, J. David; Viggiani, Gioacchino

doi:10.1007/s10035-022-01225-7

Cited by 7 publications

(6 citation statements)

References 33 publications

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“…(iv) Segmenting individual particles Using SPAM functions 38 , the raw binary images were processed in three steps that included: (a) cleaning the image via morphological opening and closing operations to smoothen borders and fill holes; (b) labeling the cleaned image to segment individual particles; and (c) cleaning the image by fixing over-and under-segmentation based on the physical size of smallest and largest particles measured in the laboratory. More details regarding segmentation were reported by Roy et al 20 .…”

Section: (Iii) Stitching Images Acquired At Different Depthsmentioning

confidence: 99%

“…Therefore, regardless of whether intact soil samples are obtained in the field, the observation, quantification, and evaluation of natural sedimentary structures are essential.X-ray computed tomography (CT) is a widely used non-destructive technique for examining objects in medical and industrial applications, as well as in research 10,11 . This technique is useful in geotechnical engineering for observing sedimentary structures or discontinuous planes, such as fissuring, in soil samples 12 ; to quantify physical properties, including particle size and shape characteristics [13][14][15][16] ; to investigate pore and contact fabrics 17,18 ; or to characterize mechanical properties such as shear responses 19,20 primarily using the discrete element method (DEM) [21][22][23][24] or three-dimensional (3D) printing technology to replicate synthetic samples [25][26][27][28][29][30] based on CT images. Such a new paradigm based on imaging, image processing, and computing properties is…”

mentioning

confidence: 99%

“…In the aforementioned previous studies, soil or rock samples were obtained in the field or reconstituted in a laboratory before image scanning. The main research focus has been on techniques of processing CT images [17][18][19][20]31,32 , methods of incorporating the results of image processing into their computation [21][22][23][24] , and laboratory tests of synthetic samples [25][26][27][28][29][30] . Moreover, there are no studies on methods of acquiring CT images in-situ, or particularly, methods of scanning the soil samples on-site, that is, in the ground.…”

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3D image scanning of gravel soil using in-situ X-ray computed tomography

Matsumura,

Kondo,

Nakamura

et al. 2023

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A typical ground investigation for characterizing geotechnical properties of soil requires sampling soils to test in a laboratory. Laboratory X-ray computed tomography (CT) has been used to non-destructively observe soils and characterize their properties using image processing, numerical analysis, or three-dimensional (3D) printing techniques based on scanned images; however, if it becomes possible to scan the soils in the ground, it may enable the characterization without sampling them. In this study, an in-situ X-ray CT scanning system comprising a drilling machine with an integrated CT scanner was developed. A model test was conducted on gravel soil to verify if the equipment can drill and scan the soil underground. Moreover, image processing was performed on acquired 3D CT images to verify the image quality; the particle morphology (particle size and shape characteristics) was compared with the results obtained for projected particles captured in a two-dimensional (2D) manner by a digital camera. The equipment successfully drilled to a target depth of 800 mm, and the soil was scanned at depths of 700, 750, and 800 mm. Image processing results showed a reasonable agreement between the 3D and 2D particle morphology images, and confirmed the feasibility of the in-situ X-ray CT scanning system.

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Section: (Iii) Stitching Images Acquired At Different Depthsmentioning

confidence: 99%

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3D image scanning of gravel soil using in-situ X-ray computed tomography

Matsumura,

Kondo,

Nakamura

et al. 2023

Sci Rep

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“…Zheng et al (2019) applied photo-elastic technique to observe particle scale responses inside shear band. Roy et al (2022) used X-ray tomography to analyse the pore space evolution of shear band. Gu et al (2014) and Jiang and Zhang (2015) studied the microscopic feature during shear band forming process using the discrete element method (DEM).…”

Section: Introductionmentioning

confidence: 99%

“…(2019) applied photo-elastic technique to observe particle scale responses inside shear band. Roy et al. (2022) used X-ray tomography to analyse the pore space evolution of shear band.…”

Section: Introductionmentioning

confidence: 99%

Assessment of shear band evolution using discrete element modelling

Yang,

Tian,

Yang

et al. 2024

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PurposeThe objective of this paper is to quantitatively assess shear band evolution by using two-dimensional discrete element method (DEM).Design/methodology/approachThe DEM model was first calibrated by retrospectively modelling existing triaxial tests. A series of DEM analyses was then conducted with the focus on the particle rotation during loading. An approach based on particle rotation was developed to precisely identify the shear band region from the surrounding. In this approach, a threshold rotation angle ω0 was defined to distinguish the potential particles inside and outside the shear band and an index g(ω0) was introduced to assess the discrepancy between the rotation response inside and outside shear band. The most distinct shear band region can be determined by the ω0 corresponding to the peak g(ω0). By using the proposed approach, the shear band development of two computational cases with different typical localised failure patterns were successfully examined by quantitatively measuring the inclination angle and thickness of shear band, as well as the microscopic quantities.FindingsThe results show that the shear band formation is stress-dependent, transiting from conjugated double shear bands to single shear band with confining stress increasing. The shear band evolution of two typical localised failure modes exhibits opposite trends with increasing strain level, both in inclination angle and thickness. Shear band featured a larger volumetric dilatancy and a lower coordination number than the surrounding. The shear band also significantly disturbs the induced anisotropy of soil.Originality/valueThis paper proposed an approach to quantitatively assess shear band evolution based on the result of two-dimensional DEM modelling.

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