Current Cognition of Rock Tensile Strength Testing by Brazilian Test

Briševac, Zlatko; Kujundžić, Trpimir; Čajić, Sandi

doi:10.17794/rgn.2015.2.2

Cited by 31 publications

(18 citation statements)

References 34 publications

(54 reference statements)

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“…1 -Length and diameter of specimen, in brittle rocks; if these are too large, they will cause some problems such as damaging the prepared samples (Briševac et al, 2015), 2 -The load applied to break the specimen; the simplest method of loading is compression, 3 -Procedure and equipment for testing; and 4 -Accuracy in fracture toughness determination.…”

Section: Testing Methodsmentioning

confidence: 99%

An Investigation Into Fracture Toughness and Mechanisms in Anisotropic Rocks Using the Acoustic Emission Method

Zadsar

Seifabad

Ahmadi

2020

MGPB

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Anisotropy in rock is among the important parameters that should be considered in studying fracture toughness and fracture mechanisms. Acoustic emission is one of the methods applied to investigate fracture mechanics and how microcracks grow in rock samples. This method can help to identify different parts of stress versus strain curves. Using this method, the current research aims to study the effect of anisotropy angles on fracture toughness and fracture mechanisms of rock samples. To study the designated parameters, the Cracked Chevron Notched Brazilian Disc (CCNBD) method was selected. Blocks of slate, as an anisotropic rock, were prepared from the Sanandaj-Sirjan zone in Iran. The sample sizes were 54 mm and 74 mm in diameter and 24 mm and 37 mm in thickness, respectively, and their anisotropy angles were 0°, 15°, 30°, 45°, 60°, 75°, and 90°. The tests were carried out in accordance with the method suggested by the International Society for Rock Mechanics (ISRM). Two acoustic sensors were mounted on the specimens to log acoustic waves and determine the acoustic parameters (rise angle and average frequency) for fracture mechanism analysis. About 10 tests were carried out for each angle of anisotropy. Based on the obtained results, it was inferred that anisotropy affects the strength and fracture toughness of rock samples. By increasing the anisotropy angle from 0° to 30°, the strength and fracture toughness decreased. Exceeding this range of angle, with an increase in the anisotropy angle, the strength and fracture toughness increased as well.

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Section: Testing Methodsmentioning

confidence: 99%

An Investigation Into Fracture Toughness and Mechanisms in Anisotropic Rocks Using the Acoustic Emission Method

Zadsar

Seifabad

Ahmadi

2020

MGPB

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“…Because of its practicality, the Brazilian test (or splitting tensile strength test) is the most popular one in ITS tests. Although the Brazilian test is applied worldwide, its deficiencies have been discussed as an important issue of the rock testing area [8][9][10][11]. Because the Brazilian test discs fail under biaxial stress distribution condition, the method is not usable to evaluate the uniaxial tensile strength values [12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Water Saturation Induced Changes in the Indirect (Brazilian) Tensile Strength and the Failure Mode of Some Igneous Rock Materials

Yasar

Komurlu

2020

GSE

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The present study concentrates on water induced strength reduction and variation of the failure mode in indirect (Brazilian) tension tests of several igneous rock materials under three moisture cases of ovendry, air-dry and fully saturated states. In this respect, two andesite and three tuff materials which contain no visible flaws were subjected to indirect tensile strength tests using the Brazilian disc method. Once the tension tests were carried out, photographs of the broken samples were taken to investigate the changes in the failure mode. As a result, it was found that tensile strengths of the samples were highly reduced with the presence of the water and the natural humidity. Additionally, it has been deduced that the failure mode of the samples mainly shifts to central fracturing with the presence of natural moisture and saturation. Although the central crack is the ideal type for the theory of Brazilian tensile strength determination, indefinite contact properties like contact angle and frictions are some notable issues to make only considering failure shapes for the validity of the test results misleading.

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“…The Brazilian test (or splitting tensile strength test) is the most popular one in the Indirect Tensile Strength (ITS) tests because of its practicality. Although the Brazilian test is applied worldwide, its deficiencies cannot be ignored and have been an important issue to investigate by the community on rock testing [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Determination of Direct Tensile Strength Values of Rock Materials by a New Test Method of Drilled Disc Tension

Komurlu

Demir

2019

Period. Polytech. Civil Eng.

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Use of drilled disc specimens was investigated with both numerical and experimental studies to determine direct tensile strengths of rock materials. A new loading apparatus with rods to insert into the drill holes of discs has been designed and manufactured to supply tension by using the compression test presses. In addition to the use of popular compressive presses for direct tension, elimination of the gluing in the standard direct tensile strength test method is a significant advantage to make possible both hard and soft rocks to be tested. The Brazilian test discs with the diameter of NX size and length to diameter ratio of 0.5 were used in tests. Different loading apparatus designs were analyzed and ideal angle of contact between rock and the loading rods was assessed to be 50° within various choices investigated in this study. The drilled discs were determined to fail due to the crack initiation under the condition of uniaxial tensile stress distribution at sidewalls of the hole. In addition to the drilled disc tension test, standard direct tensile strength tests were also carried out to take as reference and compare the results obtained from different methods. According to the results of both numerical and experimental studies, an equation was suggested to determine uniaxial tensile strengths of drilled disc specimens with 20 mm hole diameter and the contact angle of 50°.

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Current Cognition of Rock Tensile Strength Testing by Brazilian Test

Cited by 31 publications

References 34 publications

An Investigation Into Fracture Toughness and Mechanisms in Anisotropic Rocks Using the Acoustic Emission Method

An Investigation Into Fracture Toughness and Mechanisms in Anisotropic Rocks Using the Acoustic Emission Method

Water Saturation Induced Changes in the Indirect (Brazilian) Tensile Strength and the Failure Mode of Some Igneous Rock Materials

Determination of Direct Tensile Strength Values of Rock Materials by a New Test Method of Drilled Disc Tension

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