Fracture Toughness Testing of Rock

Ouchterlony, Finn

doi:10.1007/978-3-7091-2750-6_3

Cited by 47 publications

(39 citation statements)

References 36 publications

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“…Rock exhibits a crack extension resistance curve (K-resistance curve or R-resistance curve), in which, with crack growth, the resistance increases rapidly and then gently due to the formation of a fracture process zone, in a similar way to crack growth in steel and ceramics (Ouchterlony 1982). Transient creep, which exhibits a decreasing strain rate, has been observed even in the tensile stress state, as shown by three-point bending and uniaxial tension tests.…”

Section: Discussion Based On Numerical Simulationsmentioning

confidence: 97%

Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

2014

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To design and construct underground structures, it is essential to understand the mechanical properties of rock in not only compression but also tension. It is well known that water is one of the important factors affecting the deformation and failure of rock. In this study, laboratory tests and numerical simulations were conducted to understand the effect of water on rock properties in uniaxial tension. In the experiments, a testing machine previously used for uniaxial tension tests in dry conditions was modified for tests in wet conditions. Using this machine, complete stress-strain curves from the pre-to postpeak regions of water-saturated specimens in uniaxial tension were obtained. The results for granite, tuff, and two types of andesite showed that the stress-strain curves in wet conditions have a lower initial slope and lower strength than those in dry conditions, and they are strongly nonlinear in the prepeak region. Comparing the changes in the results for uniaxial tension versus compression due to water, it was found that the reduction rate of uniaxial tensile strength was greater than that of uniaxial compressive strength, while the ratio between the reduction rates was almost constant for various rocks. In numerical simulations, the stress-strain curves in the prepeak region under dry and wet conditions could be reproduced by crack extension models under uniaxial tensile stress. Numerical analyses indicated that the nonlinearity of the stress-strain curves is probably due to the longer crack extension in wet compared with dry conditions.

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Section: Discussion Based On Numerical Simulationsmentioning

confidence: 97%

Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

2014

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“…The properties listed in Table 3 are estimated perpendicular to the layer structure. The fracture toughness of the materials was estimated on a single edge notch bend (SENB) specimen (Ouchterlony 1982) under three-point bending. The fracture toughness was estimated as follows (Murakami 1987):…”

Section: Materials Properties and Experimental Conditionsmentioning

confidence: 99%

Fracture Toughness Effects in Geomaterial Solid Particle Erosion

Momber

2014

Rock Mech Rock Eng

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Effects of fracture toughness on the impingement of geomaterials (rocks and cementitious composites) by quartz particles at velocities between 40 and 140 m/s are investigated experimentally and analytically. If schist is excluded, relative erosion (in g/g) reduces according to a reverse power function if fracture toughness increases. The power exponent depends on impingement velocity, and it varies between -0.64 and -1.33. Lateral cracking erosion models, developed for brittle materials, deliver too high values for relative material erosion. This discrepancy is partly attributed to stress rate effects. Effects of R-curve behavior seem to be marginal. An integral approach E R = K 1 Á E R P ? (1 -K 1 ) Á E R L is introduced, which considers erosion due to plastic deformation and lateral cracking. A transition functionsuggested in order to classify geomaterials according to their response against solid particle impingement.

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“…Special loading fixtures using steel rollers are needed for bending load application. To determine K Ic value of the materials, methods using bending type loading are listed as semi-circular bending (SCB) method (Chong and Kuruppu 1984), chevron notched semi-circular bending (CNSCB) method (Kuruppu 1997), chevron bend (CB) test (Ouchterlony 1988) and straight edge cracked round bar bend (SECRBB) method (Ouchterlony 1982). CB method is again one of the three suggested methods of ISRM (Ouchterlony 1988) for fracture testing of rocks.…”

Section: Introductionmentioning

confidence: 99%

Investigation of proper specimen geometry for mode I fracture toughness testing with flattened Brazilian disc method

Keleş

Tutluoğlu

2011

Int J Fract

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Investigation of geometrical parameters for flattened Brazilian disc method is important, since this is a simple and attractive method for mode I fracture toughness testing on rock cores. Evaluating numerical modeling results, a parametric equation in terms of principal stresses at the center of the disc and the loading angle of the flattened end was developed. An equation was proposed for maximum stress intensity factors at critical crack lengths around stable to unstable crack propagation. Comparing fracture toughness results of flattened Brazilian disc method to the results of the suggested cracked chevron notched Brazilian disc method, geometrical parameters for flattened Brazilian discs were investigated. Diameter, loading angle of flattened ends, and thickness of andesite rock core specimens were changed to obtain comparable results to the suggested method. The closest results to the suggested method were obtained by 54 mm diameter discs with loading angles larger than 32 • , and thicknesses between 19 and 34 mm. Results were confirmed by the flattened Brazilian disc tests on a marble rock. In flattened Brazilian disc tests with smaller loading angles and larger diameters, larger fracture toughness values than the results of the suggested cracked chevron notched were obtained. However, excluding tests with large loading angles over 27 • ; specimen size was less effective on the results of these tests. Critical crack C. Keles (B) · L. Tutluoglu length parameters computed from modeling and experiments were close to each other for the flattened Brazilian disc specimens with smaller loading angles around 20 • and thickness/radius ratio equal or less than 1.1.

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Fracture Toughness Testing of Rock

Cited by 47 publications

References 36 publications

Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

Effect of Water on the Deformation and Failure of Rock in Uniaxial Tension

Fracture Toughness Effects in Geomaterial Solid Particle Erosion

Investigation of proper specimen geometry for mode I fracture toughness testing with flattened Brazilian disc method

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