Change in local void ratio distribution of sand as a function of aging time

2013 ◽  
pp. 1267-1272 ◽  
Author(s):  
M Muszynski ◽  
R Hodek
Keyword(s):  
Aging Time ◽  
Void Ratio ◽  
Ratio Distribution

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.

Influence of Void Ratio Distribution on Permeability of Porous Layer

2018 ◽  
Vol 2018.93 (0) ◽  
pp. 809
Author(s):  
Yoshiyuki YAMAGUCHI ◽  
Kimitaka WATANABE ◽  
Satoshi DOI
Keyword(s):  
Porous Layer ◽  
Void Ratio ◽  
Ratio Distribution

Void ratio redistribution in undrained triaxial extension tests on Ottawa sand

1998 ◽  
Vol 35 (2) ◽  
pp. 351-359 ◽  
Author(s):  
A Ayoubian ◽  
P K Robertson
Keyword(s):  
Phase Transformation ◽  
Void Ratio ◽  
Large Strains ◽  
Ultimate State ◽  
Ratio Distribution ◽  
Ottawa Sand ◽  
Effective Stresses ◽  
Softening Behavior ◽  
Triaxial Extension Test ◽  
Triaxial Extension

Water-pluviated samples of Ottawa sand were tested in monotonic, undrained triaxial extension tests. The specimens exhibited similar "limited strain softening" behavior, and they all experienced phase transformation from contraction to dilation at small axial strains. The tests were stopped at different stages and the samples were frozen to obtain void ratio distribution along the length of the specimens. It was shown that void ratio redistribution can start at very low axial strains in an undrained triaxial extension test. Before phase transformation, void ratio redistribution was very small, but after phase transformation void ratio redistribution started rapidly and continued until the end of the tests at ultimate state. The location of the ultimate state line in a void ratio - mean normal effective stress plot was shown to be affected by localized failure at large strains in undrained triaxial extension tests. The actual ultimate state line with respect to void ratios and effective stresses within the failure zone in the samples can be located above the average ultimate state line obtained from average measurements of void ratios and effective stresses of the entire specimens.Key words: liquefaction, testing, void ratio.

scholarly journals Simulations of Fine-Meshed Biaxial Tests with Barodesy

Geosciences ◽  
2018 ◽  
Vol 9 (1) ◽  
pp. 20
Author(s):  
Gertraud Medicus ◽  
Barbara Schneider-Muntau
Keyword(s):  
Shear Band ◽  
Void Ratio ◽  
Experimental Testing ◽  
Experimental Studies ◽  
Triaxial Tests ◽  
Biaxial Test ◽  
Average Response ◽  
Stress Strain ◽  
Ratio Distribution ◽  
Biaxial Tests

Recent experimental studies showed that shear band development starts at the beginning of triaxial tests. In experimental testing, it is impossible to obtain a soil sample with a homogeneous void ratio. Therefore, a homogeneous deformation, i.e., an element test, is questionable well before the peak. In this article we carry out finite element simulations of fine-meshed biaxial tests with the constitutive model barodesy, where the stress rate is formulated as a function of stress, stretching and void ratio. The initial void ratio in the simulations is normally distributed over all elements in a narrow range. In this article, we evaluate the pre-peak shear band development. We further compare stress paths and stress-strain curves of the biaxial test of relevant elements (e.g., in- and outside the shear band) with the results of the average response of all elements. We show how the response in an element test differs from the average response of the fine-meshed test. We present the resulting potential for understanding (early) shear band development and stress-strain behaviour in a biaxial test: The inhomogeneous void ratio distribution in a sample favours early shear band development. This effect is modelled with barodesy. The obtained stress paths and stress-strain curves show that the maximum deviatoric stress is higher in the element test than it is in the average response of the fine-meshed test.

Use of image analysis to study the microstructure of a failed sand specimen

2000 ◽  
Vol 37 (5) ◽  
pp. 1141-1149 ◽  
Author(s):  
Deh-Jeng Jang ◽  
J David Frost
Keyword(s):  
Image Analysis ◽  
Granular Materials ◽  
Shear Zone ◽  
Soil Structure ◽  
Digital Image Analysis ◽  
Void Ratio ◽  
Shear Zones ◽  
Ratio Distribution ◽  
Soil Particles ◽  
Particle Orientations

The shearing of dilatant specimens of granular materials in the laboratory is often accompanied by the development of zones of more intense shearing. The nominal behavior of the specimens during this shearing condition is dictated by the behavior of soil particles inside the shear zones. To study the behavior of soil particles inside the shear zones, quantitative evaluation of the soil structure at the particulate scale is required. This paper describes the findings of a study that used digital image analysis to examine sand structure in a specimen where a shear zone formed. Evolution of the local void ratio distribution and changes in particle orientations within and adjacent to the shear zone were quantified.Key words: image analysis, sand, microstructure, shear, critical state.

scholarly journals Investigation of the microstructure evolution in TP347HFG austenitic steel at 700°C and its characterization method

2021 ◽  
Vol 40 (1) ◽  
pp. 12-22
Author(s):  
Yuetao Zhang ◽  
Tingbi Yuan ◽  
Yawei Shao ◽  
Xiao Wang
Keyword(s):  
Austenitic Steel ◽  
Aging Time ◽  
Microstructure Evolution ◽  
Precipitate Phase ◽  
Dispersion Strengthening ◽  
Micro Hardness ◽  
Dispersed Particles ◽  
Nonlinear Ultrasonic ◽  
The Matrix ◽  
Solution Strengthening

Abstract This article reports the microstructure evolution in TP347HFG austenitic steel during the aging process. The experiments were carried out at 700°C with different aging time from 500 to 3,650 h. The metallographic results show that the coherent twin and incoherent twin are existed in the original TP347HFG grains, while they gradually vanished with the increase of the aging time. After aging for 500 h, a lot of fine, dispersed particles precipitated from the matrix, but they disappeared after aging for 1,500 h. When the aging time extend to 3,650 h, the precipitates appeared apparently coarse in TP347HFG steel, which include the M23C6 and σ phase; besides, the micro-hardness of TP347HFG also changes during the aging, which was closely related to the effect of dispersion strengthening and solution strengthening. The results of the nonlinear ultrasonic measurement reveal that the β′ of TP347HFG steel was also changed with the aging time. It first increased at 0–500 h, then reduced later, and increased finally at 1,500–3,650 h. The variation of β′ in TP347HFG was influenced by a combined effect of the twin microstructure and the precipitate phase, which indicate that the nonlinear ultrasonic technique can be utilized to characterize the microstructure evolution in TP347HFG.

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