Void ratio evolution inside shear bands in triaxial sand specimens studied by computed tomography

Géotechnique ◽  
1996 ◽  
Vol 46 (3) ◽  
pp. 529-546 ◽  
Author(s):  
J. Desrues ◽  
R. Chambon ◽  
M. Mokni ◽  
F. Mazerolle
Keyword(s):  
Computed Tomography ◽  
Void Ratio ◽  
Shear Bands

Specimen nonuniformities in water-pluviated and moist-tamped sands under undrained triaxial compression and extension

2008 ◽  
Vol 45 (7) ◽  
pp. 939-956 ◽  
Author(s):  
P. R. Thomson ◽  
R. C.K. Wong
Keyword(s):  
Computed Tomography ◽  
Axial Load ◽  
Void Ratio ◽  
Triaxial Compression ◽  
Stress Path ◽  
Saturated Sand ◽  
Ratio Distribution ◽  
X Ray ◽  
X Ray Computed ◽  
Insight Into

X-ray computed tomography (CT) methods and specialized triaxial equipment were developed to quantify void ratio distribution within saturated sand specimens reconstituted by water pluviation and moist tamping methods during undrained triaxial compression and extension. The CT measurements were obtained at several points along the stress path of each specimen without significant removal of axial load. It was observed that two reconstitution methods yielded very different void ratio distributions within specimens. Significant void ratio redistribution occurred within each specimen during the undrained shearing tests. The influences of void ratio redistribution on globally observed specimen responses are discussed. The findings of this research investigation provide unique insight into fundamental aspects of saturated sand behaviour during undrained triaxial shearing.

Size Effect on the Deformation Characteristic and Shear Band of Granular Material Based on Hypoplastity

2014 ◽  
Vol 584-586 ◽  
pp. 1789-1793
Author(s):  
Bao Lin Xiong ◽  
Chun Jiao Lu
Keyword(s):  
Size Effect ◽  
Granular Material ◽  
Void Ratio ◽  
Characteristic Length ◽  
Shear Bands ◽  
Deformation Characteristic ◽  
Test Method ◽  
Initial Void Ratio ◽  
Hypoplastic Constitutive Model ◽  
Single Set

The deformation characteristic of granular material is important. It is important factor to analysis the bearing capacity and the thickness of granular material footings. There are many factors influence the deformation of granular material, such as material characteristic, content of water, degree of compaction, test method, etc. For analyzing size effect on the deformation characteristic of granular material, hypoplastic constitutive model considering void ratio is introduced. The influence of an initial void ratio, pressure and a mean grain diameter on the deformation is investigated by polar quantities: rotations, curvatures, couple stresses and a characteristic length. Thus, the influence of density and pressure on the initiation of shear bands can be investigated with a single set of constitutive constants.

scholarly journals The initiation and progression of damage in composite overwrapped pressure vessels subjected to contact loads

2021 ◽  
pp. 073168442199212
Author(s):  
Ruben AJ Weerts ◽  
Olivier Cousigné ◽  
Klaas Kunze ◽  
Marc GD Geers ◽  
Joris JC Remmers
Keyword(s):  
Computed Tomography ◽  
Residual Strength ◽  
Shear Bands ◽  
Pressure Vessels ◽  
Burst Pressure ◽  
Contact Loads ◽  
Computed Tomography Scans ◽  
Progressive Growth ◽  
Observed Damage ◽  
Impact Energies

In order to investigate the residual strength of composite overwrapped pressure vessels subjected to impact loads, an extensive experimental study has been performed. The vessels are loaded up to different mechanical work levels (quasi-static) or with various impact energies (dynamic). After loading, the emerged damage in the pressure vessel is examined using computed tomography scans. The tests of vessels up to various energies enable us to visualize the initiation and progressive growth of damage. The overall influence of the damage is subsequently quantified by means of a burst pressure test. Accordingly, the reduction of burst pressure can be used to evaluate the global severity of the observed damage in the computed tomography scan. From the experiments, it is concluded that the first failure mechanisms, that is, delaminations, do not cause a meaningful reduction of the burst pressure. Shear bands, on the other hand, which are formed thereafter, do induce a significant decrease of the residual strength.

Quantifying Void Ratio Variation in Sand Using Computed Tomography

2000 ◽  
Author(s):  
Khalid A. Alshibli ◽  
Susan N. Batiste ◽  
Roy A. Swanson ◽  
Stein Sture ◽  
Nicholas C. Costes ◽  
...  
Keyword(s):  
Computed Tomography ◽  
Void Ratio ◽  
Ratio Variation

scholarly journals Imaging the root–rhizosphere interface using micro computed tomography: quantifying void ratio and root volume ratio profiles

2021 ◽  
Vol 249 ◽  
pp. 11005
Author(s):  
Tomás Lascurain ◽  
Vasileios Angelidakis ◽  
Saimir Luli ◽  
Sadegh Nadimi
Keyword(s):  
Computed Tomography ◽  
Root Growth ◽  
Computational Models ◽  
Void Ratio ◽  
Early Stage ◽  
Volume Ratio ◽  
Physical Characteristics ◽  
Micro Computed Tomography ◽  
Soil Physical Characteristics ◽  
Soil Fabric

Root growth alters soil fabric and consequently its mechanical and physical properties. Recent studies show that roots induce compaction of soil in their immediate vicinity, a region that is central for plant health. However, high quality quantification of root influence on the soil fabric, able to inform computational models is lacking from the literature. This study quantifies the relationship between soil physical characteristics and root growth, giving special emphasis on how roots in early stage formation influence the physical architecture of the surrounding soil structure. High-resolution X-ray micro-Computed Tomography (µCT) is used to acquire three dimensional images of two homogeneously-packed samples. It is observed that the void ratio profile extending from the soil-root interface into the bulk soil is altered by root growth. The roots considerably modify the immediate soil physical characteristics by creating micro cracks at the soil-root interface and by increasing void ratio. This paper presents the mechanisms that led to the observed structure as well as some of the implications that it has in such a dynamic zone.

X-ray microtomography

1988 ◽  
Vol 46 ◽  
pp. 998-999
Author(s):  
H.W. Deckman ◽  
B.F. Flannery ◽  
J.H. Dunsmuir ◽  
K.D' Amico
Keyword(s):  
Computed Tomography ◽  
Internal Structure ◽  
Imaging Technique ◽  
Three Dimensional ◽  
Tissue Structure ◽  
Individual Element ◽  
X Ray ◽  
Non Invasive ◽  
Panoramic Imaging ◽  
Three Dimensional Images

We have developed a new X-ray microscope which produces complete three dimensional images of samples. The microscope operates by performing X-ray tomography with unprecedented resolution. Tomography is a non-invasive imaging technique that creates maps of the internal structure of samples from measurement of the attenuation of penetrating radiation. As conventionally practiced in medical Computed Tomography (CT), radiologists produce maps of bone and tissue structure in several planar sections that reveal features with 1mm resolution and 1% contrast. Microtomography extends the capability of CT in several ways. First, the resolution which approaches one micron, is one thousand times higher than that of the medical CT. Second, our approach acquires and analyses the data in a panoramic imaging format that directly produces three-dimensional maps in a series of contiguous stacked planes. Typical maps available today consist of three hundred planar sections each containing 512x512 pixels. Finally, and perhaps of most import scientifically, microtomography using a synchrotron X-ray source, allows us to generate maps of individual element.

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