Effects of intermediate principal stress on tensile strength of rocks

Phueakphum, Decho; Fuenkajorn, Kittitep; Walsri, Chaowarin

doi:10.1007/s10704-013-9829-0

Cited by 16 publications

(11 citation statements)

References 10 publications

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“…In summary, the second and third subcategories share the same compression and extension meridians with the conventional HB criterion and thus give a TXC strength same as the triaxial extension (TXE) strength as well as an equal biaxial compression as the uniaxial compression strengths. However, many experimental tests of rocks have already revealed that TXE strength is generally higher by 10%–20% than TXC strength 4,35–38 . Similar findings are also reported for concrete materials.…”

Section: Introductionsupporting

confidence: 77%

“…However, many experimental tests of rocks have already revealed that TXE strength is generally higher by 10%-20% than TXC strength. 4,[35][36][37][38] Similar findings are also reported for concrete materials. For example, triaxial experiments on concrete cylinders clearly demonstrates that a substantial difference of shear strength in TXC and TXE states, which diminishes with increasing confinement 39 ; equal biaxial compression strength of concrete is around 15%-16% higher than uniaxial compression strength.…”

Section: Introductionsupporting

confidence: 67%

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A three‐dimensional Hoek–Brown failure criterion based on an elliptical Lode dependence

Jiang

Yang

2020

Num Anal Meth Geomechanics

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A new three-dimensional (3D) Hoek-Brown (HB) failure criterion based on an elliptical Lode dependence is proposed to describe failure of rocks and concrete under multiaxial stress states. This criterion not only inherits all benefits of the classical HB criterion that is developed for the triaxial compression (TXC) of rocks but also accounts for the effect of the intermediate principal stress. It is capable of representing the strength difference between the triaxial extension (TXE) and TXC with the introduction of an additional coefficient k (0.5 ≤ k ≤ 1.0), which can be derived from TXE tests or taken as 0.53 for rocks in cases where the TXE test data is unavailable. Other two material constants (m i and σ ci) involved in this criterion can be obtained from TXC tests. Additionally, the failure surface of this criterion is smooth and convex on the deviatoric stress plane when 0.5 < k ≤ 1.0. The new criterion achieves very good fit to the test data of TXC/TXE, biaxial compression, and polyaxial compression (PXC) on a wide variety of rock materials and concrete, reported in the literature. Comparison of the new criterion with an existing 3D HB criterion based on the same Lode dependence has demonstrated that the new criterion performs better than the latter for test data of rock and concrete under multiaxial stress states except for PXC test data of one rock type. Finally, the influence of values of k on the accuracy of the new criterion is discussed.

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Section: Introductionsupporting

confidence: 77%

Section: Introductionsupporting

confidence: 67%

A three‐dimensional Hoek–Brown failure criterion based on an elliptical Lode dependence

Jiang

Yang

2020

Num Anal Meth Geomechanics

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“…where (14) and (15) into Equation 1and considering that z = x + iy, α + β = 90°, the stress solution for the chordwise loading is obtained as follows:…”

Section: Advances In Mathematical Physicsmentioning

confidence: 99%

“…From the current research results, tensile strength measured by a splitting test is still quite discrete and is affected by many factors, such as the thickness of disc specimen, the contact mode of the load, and the size of the spacer. For example, aiming at the size effect [14][15][16][17] caused by the thickness to diameter ratio, the result shows that the tensile stress on the axle wire of the disc is not a constant but a high-end, low-middle distribution, with an obvious spatial effect. At the same time, the compression failure near the loading point of the disc violates the hypothesis of the initiation of the crack from the center of the disc due to the strong stress concentration.…”

Section: Introductionmentioning

confidence: 99%

Deviation Effect of Coaxiality on the Rock Brazilian Split

Zhao

Zhang

et al. 2020

Advances in Mathematical Physics

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Tension failure is one of the main forms of instability in geotechnical engineering. Aiming at the calculation error caused by the loading direction deviation of the Brazilian disc splitting method, a mechanical model of a disc under chord loading was constructed firstly. Based on the theory of complex variable function, the analytic solutions of stresses in a circular disc were deduced, and the calculation error of the tensile strength under chord loading was characterized by defining the error impact rate. And the stress distribution of a disc and the law of rock fracture under chord loading were detailed analyzed through numerical calculation. Through numerical calculation, the stress distribution of the disc and rock failure law under chordwise loading are discussed in detail. The results show that the stress concentration near the loading point is stronger under the chordwise loading comparing with the radial loading, which makes the disc more vulnerable to produce compression failure near the loading point. The disc exhibits a maximum tensile stress and a minimum compressive stress at the intersection of the loaded string and the horizontal diameter, so that tensile rupture damage is likely to occur here. With the increase of deviation angle, the tensile strength measured by the Brazilian splitting test decreases gradually, and the influence rate of error increases significantly. The proposed analytical solution under chord loading provides theoretical guiding significance for nonradial splitting failure of a disc.

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“…However, the pertinent literature shows only a limited number of strength data points in the tensile domain (Hagengruber et al, 2021;Jaeger, 1963;Ramsey & Chester, 2004), and the shape of strength envelopes in the tensile domain has not been thoroughly investigated. Phueakphum et al (2013) found that tensile strength of rocks increases with intermediate principal stress using four-point bending test and biaxial flexural test. The dog-bone shaped rock samples were used to test the tensile behavior of Carrara marble (Ramsey & Chester, 2004;Rodriguez, 2005), Berea sandstone (Bobich, 2005) and Longmaxi Shale (Lan et al, 2019) under confining pressure, their dataset also demonstrate an increase of tensile strength with confining pressure.…”

mentioning

confidence: 99%

Rock Failure Envelope and Behavior Using the Confined Brazilian Test

Ghassemi

2021

JGR Solid Earth

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In laboratory rock testing, there are three approaches to emulate the three-dimensional subsurface in situ stress states namely, the conventional triaxial compression test, polyaxial compression test, and triaxial extension test. The conventional triaxial compression test has the limitation that the minimum principal stress  3 E is always equal to the intermediate principal stress  2 E; polyaxial compression test overcomes the above-mentioned limitation and creates three unequal compressive principal stresses; neither conventional compression test nor polyaxial compression test can create tensile principal stress. Triaxial extension test can create a tensile principal stress but has the limitation that the intermediate principal stress  2 Eequals the maximum principal stress  1 . ETriaxial (confined) Brazilian test is a cost-effective alternative to the conventional triaxial extension test with samples of dog-bone geometry; it overcomes the limitation of the conventional triaxial extension test by creating three unequal principal stresses at the center of the Brazilian disc. There are many cases where rock behavior in the confined tension region is of interest, e.g., wellbore breakouts, rock-bursts and spalling can occur under confined tensile stress state (Hoek & Martin, 2014). The extent of excavation damage zone is greatly affected by the tensile strength measured in confined tension conditions and additionally, hydraulic fracturing also occurs in confined tension stress conditions.

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Effects of intermediate principal stress on tensile strength of rocks

Cited by 16 publications

References 10 publications

A three‐dimensional Hoek–Brown failure criterion based on an elliptical Lode dependence

A three‐dimensional Hoek–Brown failure criterion based on an elliptical Lode dependence

Deviation Effect of Coaxiality on the Rock Brazilian Split

Rock Failure Envelope and Behavior Using the Confined Brazilian Test

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