The Effect of the Loading Rate on Stress-Strain Characteristics of Tuff

Kohmura, Yuichi; Inada, Youichi

doi:10.2472/jsms.55.323

Cited by 7 publications

(6 citation statements)

References 4 publications

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“…Finding the increase of the UCS values with an increase in loading rate is parallel with the results obtained from other previous studies carried out by different researchers [13][14][15][16][17]. Under a load controlled rate (kN/s), change in the size causes also a change in the strain rate (s −1 ) that a decrease of the size makes an increase in the rate value.…”

Section: Discussionsupporting

confidence: 87%

“…In the UCS tests of rock materials, the loading rate is many times load control selected with the unit of kN/s. It is known that the increase in the loading rate makes also an increase in the UCS values [13][14][15][16][17]. Big size specimens tested under a same load controlled rate (kN/s) have lower deformation rates (mm/min) and strain rates (s −1 ) which cause to measure lower UCS values than those of the specimens with smaller sizes.…”

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confidence: 99%

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Loading rate conditions and specimen size effect on strength and deformability of rock materials under uniaxial compression

Komurlu

2018

Geo-Engineering

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Determination of the uniaxial compressive strength (UCS), one of the most crucial inputs in rock engineering design works is detailed in different standards and suggestions by the International Society for Rock Mechanics and Rock Engineering (ISRM). The relevant standards and suggestions include some statements to select appropriate values of different parameters like geometry, size and loading rate. As ideal geometry of the UCS test specimens, length to diameter (L/D) ratio of the cylindrical specimens is suggested to be 2-2.5 by ASTM (American Society for Testing and Materials) and TSE (Turkish Standards Institution). On the other hand, the ratio should be 2.5-3 according to ISRM suggestions [1][2][3]. The geometry effect on the UCS values is one of the wellstudied topics in rock testing. It is known that an increase in the ratio of length to diameter of the cylindrical core specimens make strength values to decrease [4][5][6].The specimen size has also a significant effect on the UCS test results that an increase in the size makes a decrease in the UCS values [7][8][9]. Stress concentration at the crack

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Section: Discussionsupporting

confidence: 87%

mentioning

confidence: 99%

Loading rate conditions and specimen size effect on strength and deformability of rock materials under uniaxial compression

Komurlu

2018

Geo-Engineering

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“…dam foundations and underground openings), which may lead to a non-conservative analysis and design of the relevant geologic structures. Okubo et al (1992), Ishizuka et al (1993), Ray et al (1999), Li and Xia (2000) and Kohmura and Inada (2006) conclude from their experimental results that rock uniaxial compressive strengths tend to increase with strain and loading rates, respectively. For brittle rocks the loading rate effects on the elastic modulus remain inconclusive (Blanton 1981;Chong et al 1987;Wang 2008;Okubo et al 2001Okubo et al , 2006.…”

Section: Introductionmentioning

confidence: 84%

Influence of Loading Rate on Deformability and Compressive Strength of Three Thai Sandstones

Fuenkajorn

Kenkhunthod

2010

Geotech Geol Eng

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Uniaxial and triaxial compressive strength tests have been performed using a polyaxial load frame to assess the influence of loading rate on the strength and deformability of three Thai sandstones. The applied axial stresses are controlled at constant rates of 0.001, 0.01, 0.1, 1.0 and 10 MPa/s. The confining pressures are maintained constant at 0, 3, 7 and 12 MPa. The sandstone strengths and elastic moduli tend to increase exponentially with the loading rates. The effects seem to be independent of the confining pressures. An empirical loading rate dependent formulation of both deformability and shear strength is developed for the elastic and isotropic rocks. It is based on the assumption of constant distortional strain energy of the rock at failure under a given mean normal stress. The proposed multiaxial criterion well describes the sandstone strengths within the range of the loading rates used here. It seems reasonable that the derived loading rate dependent equations for deformability and shear strength are transferable to similar brittle isotropic intact rocks.

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“…[], Ray et al . [], Li and Xia [], Kohmura and Inada [], Fuenkajorn and Kenkhunthod [], and Wang et al . [] conclude from experimental observations that the uniaxial compressive strength of rock increases with an increase in strain and loading rates.…”

Section: Introductionmentioning

confidence: 99%

“…Apart from the microstructure itself, the strength and failure mechanisms of coal are also affected by the loading rate . Okubo et al [1992], Ishizuka et al [1993], Ray et al [1999], Li and Xia [2000], Kohmura and Inada [2006], Fuenkajorn and Kenkhunthod [2010], and Wang et al [2013] conclude from experimental observations that the uniaxial compressive strength of rock increases with an increase in strain and loading rates. However, it remains unanswered how the combined effects of microheterogeneity and loading/strain rates influence the strength and failure behavior of coal.…”

Section: Introductionmentioning

confidence: 99%

Failure mechanisms in coal: Dependence on strain rate and microstructure

et al. 2014

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The brittle coal failure behavior under various axial strain rates from 10 À3 to 10 À2 s À1 is experimentally and numerically studied. The numerical microscale finite difference model is built on the accurate X-ray microcomputed tomography images, which provides a ground-breaking and bottom-up approach to investigate the effects of microstructure on coal failure under various strain rates. Experimentally, prior to loading, the coal sample is scanned, and the three-dimensional coal structure model is constructed. The microheterogeneous structures are incorporated in the model, which facilitates the deformation and failure mechanism analysis under different loading conditions. The results reveal that the microheterogeneous structures significantly affect the evolution of stress concentrations and deformation behaviors in the sample. The coal tends to fail in the shear mode before the peak strength, since the shear zone is created with high displacements. However, tensile failure ultimately controls the failure process after the peak strength. Notably, the strain rate dependence of coal strength is observed, and an empirical relationship is proposed to describe the dynamic strength of the coal under various loading strain rates. Importantly, the coal strengthens with an increase in strain rate. For brittle material, such as coal, the strength and failure mechanism are strain rate and microstructure dependent. The strain rate-dependent coal strength index (n) is found to be a dynamic parameter in the range of strain rate from 10 À3 to 10 À2 s À1, and this finding may extend the concept of strain rate dependence over a broader range of loading conditions.

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The Effect of the Loading Rate on Stress-Strain Characteristics of Tuff

Cited by 7 publications

References 4 publications

Loading rate conditions and specimen size effect on strength and deformability of rock materials under uniaxial compression

Loading rate conditions and specimen size effect on strength and deformability of rock materials under uniaxial compression

Influence of Loading Rate on Deformability and Compressive Strength of Three Thai Sandstones

Failure mechanisms in coal: Dependence on strain rate and microstructure

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