Estimation of Fracture Toughness of Anisotropic Rocks by Semi-Circular Bend (SCB) Tests Under Water Vapor Pressure
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In order to investigate the influence of water vapor pressure in the surrounding environment on mode I fracture toughness (K Ic) of rocks, semi-circular bend (SCB) tests under various water vapor pressures were conducted. Water vapor is one of the most effective agents which promote stress corrosion of rocks. The range of water vapor pressure used was 10−2 to 103 Pa, and two anisotropic rock types, African granodiorite and Korean granite, were used in this work. The measurement of elastic wave velocity and observation of thin sections of these rocks were performed to investigate the microstructures of the rocks. It was found that the distribution of inherent microcracks and grains have a preferred orientation. Two types of specimens in different orientations, namely Type-1 and Type-3, were prepared based on the anisotropy identified by the differences in the elastic wave velocity. K Ic of both rock types was dependent on the water vapor pressure in the surrounding environment and decreased with increasing water vapor pressure. It was found that the degree of the dependence is influenced by the orientation and density of inherent microcracks. The experimental results also showed that K Ic depended on the material anisotropy. A fracture process was discussed on the basis of the geometry of fractures within fractured specimens visualized by the X-ray computed tomography (CT) method. It was concluded that the dominant factor causing the anisotropy of K Ic is the distribution of grains rather than inherent microcracks in these rocks.
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Estimation of Fracture Toughness of Anisotropic Rocks by Semi-Circular Bend (SCB) Tests Under Water Vapor PressureKataoka, M.; Obara, Y.; Kuruppu, Mahinda (2014)In order to investigate the influence of water vapor pressure in the surrounding environment on mode Ifracture toughness (KIc) of rocks, semi-circular bend (SCB) tests under various water vapor pressures were conducted. ...
Estimation of fracture toughness of anisotropic rocks by SCB test and visualization of fracture by means of X-ray CTKataoka, M.; Obara, Y.; Kuruppu, Mahinda (2012)In order to investigate the influence of anisotropic characteristics of rock andwater vapor pressure of surrounding environment on fracture toughness, a series of Semi-Circular Bend (SCB) tests under various water vapor ...
Determination of Fracture Toughness of Anisotropic Rocks Under Water Vapour Pressure by Semi-Circular Bend TestKuruppu, Mahinda; Obara, Y.; Kataoka, M. (2010)Failure of rock materials is a process of crack propagation. Crack initiation takes place when the crack tip stress intensity K reaches a critical value called fracture toughness, K1C. The rock fracture toughness is known ...