Pre-Peak and Post-Peak Rock Strain Characteristics During Uniaxial Compression by 3D Digital Image Correlation

Munoz, H.; Taheri, Abbas; Chanda, Emmanuel

doi:10.1007/s00603-016-0935-y

Cited by 207 publications

(69 citation statements)

References 31 publications

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“…Thus, the failure behavior of coal is different from that of compact rocks due to the effect of primary cracks and defects. Munoz et al [15] conducted a uniaxial compression test of sandstone and realized that the strain field increased uniformly and localization did not appear in the pre-failure region. However, in the uniaxial compression test of coal, localization appeared earlier in the pre-failure region, as shown in Figure 5.…”

Section: Discussionmentioning

confidence: 99%

“…Although CT can be used to observe the internal cracks during rock failure, CTs are larger and more expensive than a DIC instrument. DIC has been employed in experimental studies on rock materials but is mostly used in unconfined [15][16][17], Brazilian split [18,19] tests with the two-dimensional DIC method. Owing to the limitation of the pressure cell of the loading apparatus, which is usually made of metal, DIC is less favored in the triaxial compression testing of rock or coal.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Tang

Okubo

et al. 2018

Energies

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Abstract:To investigate the progressive failure process of coal, a series of uniaxial and triaxial compression tests were conducted and a novel 3D digital image correlation instrument with six cameras combined with a special transparent pressure cell was used for the strain measurement. The stress thresholds of coal were obtained in uniaxial and triaxial compression. The energy evolution during the compression was discussed, coupled with the crack volumetric strain. The field strain of the whole specimen surface and crack propagation at different stress levels were described to study the progressive failure mechanism of coal. The average stress level of crack initiation and crack damage of coal in uniaxial compression are 43.75% and 63.03%, while that in the triaxial compression are 74.53% and 89.84%, respectively. The dissipation energy evolution corresponds to the crack volumetric strain, while the elastic energy release leads to flake ejection and coal failure. The crack evolution and localization of coal indicated the progressive failure process that the coal sample undergoes in tension failure in uniaxial compression and in tension-shear failure in triaxial compression. The findings of this study can serve as a reference to understand the failure process of coal and improve the stability and safety of mining engineering.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Tang

Okubo

et al. 2018

Energies

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“…However, these techniques are usually only suitable for observing the damaged specimens after the experiments, rather than reflecting crack development during the damage process of rock in real time. With the development of graphics processing technology, a nondestructive measurement technology, that is, digital image correlation (DIC) method, has been successfully applied to the nondestructive testing of rock, concrete, metal and other engineering materials 19,20 . By using the DIC technology, not only the full‐field displacement and strain distribution during the rock fracture process can be obtained but the cracking characteristics such as crack shape, crack opening displacement and process zone length can also be extracted 21,22 .…”

Section: Introductionmentioning

confidence: 99%

Experimental investigation of fracture damage of notched granite beams under cyclic loading using DIC and AE techniques

Tang

Chen

Dai

et al. 2020

Fatigue Fract Eng Mat Struct

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Fracture experiments of three-point bending notched granite beams were performed under cyclic loading using digital image correlation (DIC) and acoustic emission (AE) techniques. The damage evolution process of the specimen under cyclic loading was analysed on the basis of AE ring count and b value. The strain and displacement fields and the fracture process zone (FPZ) ahead of the crack tip were revealed by DIC. The results showed that the AE characteristics of rock fracture indicated a noticeable Kaiser effect in the stage of cyclic loading and unloading. Moreover, when the loading force reached 70% of its peak value, the AE characteristics showed the Felicity effect. The damage produced during the loading-unloading process contributed to the development of the cracks leading to the catastrophic fracture. Besides, a relatively high loading rate was found to help to suppress the development of the FPZ at the crack tip. K E Y W O R D Sacoustic emission, cyclic loading, digital image correlation, fracture damage, rock

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“…In laboratory tests, the triaxial unloading tests, in which the axial stress 1 increases or remain unchanged after the unloading point, while the confining stress ( 3 ) decreases, are used to simulate the unloading phenomenon during tunneling (Brady and Brown 2013;Xue et al 2017). The influence of unloading-confining pressure on the mechanical properties of rock has been investigated through experimental tests (He et al 2010;Huang et al 2001;Lemaitre and Desmorat 2005;Xie and He 2004;Moradian et al 2016;Munoz et al 2016;Adushkin et al 2016). However, studies about unloading tests rarely take chemical environments into consideration, and the microscopic-scale investigations of chemically corroded rocks under states of unloading-confining pressure are few.…”

Section: Introductionmentioning

confidence: 99%

Experimental Investigation of the Permeability and Mechanical Behaviours of Chemically Corroded Limestone Under Different Unloading Conditions

Zhong

Eshiet³

et al. 2019

Rock Mech Rock Eng

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This paper investigates the mechanical properties and permeability of chemically corroded rock during deep underground tunneling. Nuclear magnetic resonance tests are carried out to quantify the chemical damage of limestone samples at the microscopic scale. Coupled hydrostatic pressure-unloading tests at different unloading rates are also conducted on these chemically corroded limestone samples to investigate permeability changes and chemical effects on mechanical behaviours. Magnetic resonance imaging, T 2 spectrum distribution and porosity of the samples are obtained, and the chemical micro damage is visualized and quantified. The relationship between permeability and mechanical behaviors of the rock under hydrochemical-mechanical coupled effects is investigated. The results show that the permeability development process of the chemical corroded samples can be divided into three stages: at the first stage, the permeability initially decreases, and the second stage starts at the inflection point of the permeability curve, from where the permeability begins to increase slightly. At the third stage, the permeability of the limestone increases dramatically until the sample is ruptured. Chemical corrosion and unloading rates have a combined and significant influence on the development of micro cracks in rocks, which is the root cause of the permeability changes. A stress-permeability model is proposed to describe the permeability and stresses in chemical-corroded limestone; this can be adopted for other sedimentary rocks.

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Pre-Peak and Post-Peak Rock Strain Characteristics During Uniaxial Compression by 3D Digital Image Correlation

Cited by 207 publications

References 31 publications

Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Study on the Progressive Failure Characteristics of Coal in Uniaxial and Triaxial Compression Conditions Using 3D-Digital Image Correlation

Experimental investigation of fracture damage of notched granite beams under cyclic loading using DIC and AE techniques

Experimental Investigation of the Permeability and Mechanical Behaviours of Chemically Corroded Limestone Under Different Unloading Conditions

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