An Investigation on the Fabric Type Dependency of the Crack Damage Thresholds in Brittle Rocks

Ghazvinian, E.; Diederichs, Mark S.; Labrie, D.; Martin, C. Derek

doi:10.1007/s10706-015-9909-1

Cited by 30 publications

(17 citation statements)

References 36 publications

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“…The CI results for all included angle cases are plotted together, as any variations as a function of included angle were found to be statistically insignificant relative to the natural variability in the results obtained (ANOVA p-value = 48% from a comparison of unconfined CI values). This result is consistent with the finding of Ghazvinian et al 20 from a study of several anisotropic rocks that CI is a relatively anisotropy-insensitive damage threshold.…”

Section: Analysis Of Test Resultssupporting

confidence: 93%

“…13), which is again consistent with the findings of Ghazvinian et al 20 As in the case of the peak strength, the 30° included angle results show a much lower CD than the other cases, with the 0° included angle tests having the highest CD values. The variations in the individual Hoek-Brown fit parameters (unconfined fit value and m i ) for CD at different included angles are shown in Fig.…”

Section: Analysis Of Test Resultssupporting

confidence: 89%

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Experimental study on the confinement-dependent characteristics of a Utah coal considering the anisotropy by cleats

Kim

Walton

Larson

et al. 2018

International Journal of Rock Mechanics and Mining Sciences

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Characterizing a coal from an engineering perspective for design of mining excavations is critical in order to prevent fatalities, as underground coal mines are often developed in highly stressed ground conditions. Coal pillar bursts involve the sudden expulsion of coal and rock into the mine opening. These events occur when relatively high stresses in a coal pillar, left for support in underground workings, exceed the pillar’s load capacity causing the pillar to rupture without warning. This process may be influenced by cleating, which is a type of joint system that can be found in coal rock masses. As such, it is important to consider the anisotropy of coal mechanical behavior. Additionally, if coal is expected to fail in a brittle manner, then behavior changes, such as the transition from extensional to shear failure, have to be considered and reflected in the adopted failure criteria. It must be anticipated that a different failure mechanism occurs as the confinement level increases and conditions for tensile failure are prevented or strongly diminished. The anisotropy and confinement dependency of coal behavior previously mentioned merit extensive investigation. In this study, a total of 84 samples obtained from a Utah coal mine were investigated by conducting both unconfined and triaxial compressive tests. The results showed that the confining pressure dictated not only the peak compressive strength but also the brittleness as a function of the major to the minor principal stress ratio. Additionally, an s-shaped brittle failure criterion was fitted to the results, showing the development of confinement-dependent strength. Moreover, these mechanical characteristics were found to be strongly anisotropic, which was associated with the orientation of the cleats relative to the loading direction.

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Section: Analysis Of Test Resultssupporting

confidence: 93%

Section: Analysis Of Test Resultssupporting

confidence: 89%

Experimental study on the confinement-dependent characteristics of a Utah coal considering the anisotropy by cleats

Kim

Walton

Larson

et al. 2018

International Journal of Rock Mechanics and Mining Sciences

View full text Add to dashboard Cite

show abstract

“…The CI stress ratios ( ci / cn ) at first decreased and then increased as the flaw inclination angle increased, which was also observed in some references [7,32,39]. With the increasing of flaw length, the variation shape of the CI stress ratios changed from "V" into "U"; note that some points are not within the scope of the law.…”

Section: Discussionsupporting

confidence: 65%

A Numerical Research on Crack Process of Gypsum Containing Single Flaw with Different Angle and Length in Uniaxial Loading

Dai

Zhang

2018

Shock and Vibration

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To investigate the crack behaviour of rock or rock-like material in uniaxial loading, a series of numerical simulations were conducted on gypsum specimens containing a single flaw with different inclination angle (0 ∘ -90 ∘ ) and length (10 mm-30 mm). Based on the numerical simulations results, the effect of flaw length on peak strength, the CI stress, and the CD stress were investigated with different inclination angles. The results show that the peak strength decreased initially and then increased with increasing of the flaw angle. Meanwhile, the peak strength decreased gradually when the length of the preexisting flaw increased. When the inclination angle was 30 ∘ , 45 ∘ , and 60 ∘ , the reduction degree of peak strength increased with increasing of the flaw length. The CI stress and CD stress not only depend on the inclination angle but also depend on flaw length. Four types of crack were observed in numerical simulations. The present research facilitates increased understanding of crack behaviour of rock under different conditions.

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“…Microstructure characteristics are related to the grain size, grain shape, and distribution in the matrix, porosity, interlocking, mineralogical composition, quartz content, and etc. So far many laboratory studies have been done for finding the relationship between microstructures of rock and macro scale features (Olsson, 1974;Eberhardt et al, 1999;Palchik & Hatzor, 2004;Tandon & Gupta, 2013;Amann et al, 2014;Ghazvinian et al, 2015;Ündül et al, 2015;Ündül, 2016;Farrokhrouz & Asef, 2017;Festa et al, 2018;Garia et al, 2019;Aladejare, 2020;Hemmati et al, 2020), as well as numerical simulation by discrete element method (Lan et al, 2010;Nicksiar & Martin, 2014;Tan et al, 2016), however, many of the results are not conclusive.…”

Section: Introductionmentioning

confidence: 99%

Physical Parameters, Tensile and Compressive Strength of Dolomite Rock Samples: Influence of Grain Size

Lakirouhani

Asemi

Zohdi

et al. 2020

Journal of Civil Engineering and Management

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The purpose of this paper is to investigate the strength, physical and engineering index parameters of selected dolomitic rocks with emphasis on grain size. For this purpose, three groups of dolomite from north western Iran, with the same mineral composition but different grain size, were selected; fine grain, medium grain and coarse grain. Three sets of laboratory experiments are performed on 32 samples: first; petrography tests for determining mineral composition and their percentage, and microstructure of rock containing grain size and grain size distribution, second; experiments to determine the physical properties of the rocks included density, compressional and shear wave velocity, and the third category of experiments included uniaxial compressive strength test, Brazilian tensile strength and point load strength. According to the results; there are significant positive correlation between grain size and uniaxial compressive strength (r = 0.89), point load strength (r = 0.58), Brazilian strength (r = 0.69), and average Young’s modulus (r = 0.64). Also, with increasing grain size, density decreases (r = –0.77). There is strong correlation between compressional wave velocity and shear velocity (r = 0.88). There are also a strong correlation among the uniaxial compressive strength, Brazilian tensile strength and point load strength.

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An Investigation on the Fabric Type Dependency of the Crack Damage Thresholds in Brittle Rocks

Cited by 30 publications

References 36 publications

Experimental study on the confinement-dependent characteristics of a Utah coal considering the anisotropy by cleats

Experimental study on the confinement-dependent characteristics of a Utah coal considering the anisotropy by cleats

A Numerical Research on Crack Process of Gypsum Containing Single Flaw with Different Angle and Length in Uniaxial Loading

Physical Parameters, Tensile and Compressive Strength of Dolomite Rock Samples: Influence of Grain Size

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