Stress-induced Crack Path in Aji Granite under Tensile Stress

Kudo, Yozo; Sano, Osam; Murashige, Naokuni; Mizuta, Yoshiaki; Nakagawa, Koji

doi:10.1007/978-3-0348-6191-5_7

Cited by 2 publications

(2 citation statements)

References 17 publications

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“…Fine‐grained granite from the Aji region of Japan was used for our experiments. Aji granite comprises 30% quartz, 37% plagioclase, 24% K‐feldspar, and 8% biotite, with an average grain size of 0.3 mm (Kudo et al, ). The apparent density was determined to be 2.65 g/cm 3 , and the porosity under ambient conditions was determined to be 0.7% based on the difference between the dry and wet masses (Table ).…”

Section: Experimental Methodsmentioning

confidence: 99%

Evolution of Elastic Wave Velocities and Amplitudes During Triaxial Deformation of Aji Granite Under Dry and Water‐Saturated Conditions

Zaima

Katayama

2018

JGR Solid Earth

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Elastic wave velocities and amplitudes in fine‐grained Aji granite are measured during a series of deformation experiments under both dry and fluid‐saturated conditions, where compressional and shear waves traveled in a direction normal to the compressional axis, and shear wave was polarized normal to the compressional axis. In the early stages of deformation, both VP and VS increase slightly due to closure of preexisting cracks and then decrease due to nucleation and crack growth as the sample approaches failure. During deformation, the different sensitivities of compressional and shear waves to fluid‐filled cracks mean that the ratio VP/VS tends to increase for wet experiments and decrease for dry experiments prior to failure. The relative changes in elastic wave amplitudes are also related to deformation and fluid saturation: amplitude decreases at high differential stresses due to the opening of cracks oriented subparallel to the axis of maximum compression, whereas a relatively minor change in amplitude was observed under fluid‐saturated conditions. Thus, the changes in velocity and amplitude during the deformation experiments are linked to crack development and geometry. However, this sensitivity differs between dry and fluid‐saturated conditions. The monitoring of fluid injection volumes during fluid‐saturated experiments shows that decreasing elastic wave velocities and amplitudes coincide with increasing fluid injection. These systematic relationships among elastic wave velocity, amplitude, crack development, and fluid saturation suggest that understanding changes in seismic wave properties can offer significant insights into the temporal changes in the structure of fracture zones.

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Section: Experimental Methodsmentioning

confidence: 99%

Evolution of Elastic Wave Velocities and Amplitudes During Triaxial Deformation of Aji Granite Under Dry and Water‐Saturated Conditions

Zaima

Katayama

2018

JGR Solid Earth

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“…This phenomenon is due to the fundamental influence that crack proximity has on stress intensity overall [ Anderson , ]. In such cases, crack growth is fastest in regions and/or directions of highest crack density or directions parallel to a preexisting microcrack fabric [e.g., Kudo et al , ; Nara and Kaneko , ; Zhao , ]. As such zones of high microfracture or flaw density—for example, along bedding planes—will experience faster subcritical cracking, leading eventually to more prominent macrocracks, as is commonly observed in the field (e.g., Figure b).…”

Section: Existing Literature Implicates Climate‐dependent Subcriticalmentioning

confidence: 98%

Mechanical weathering and rock erosion by climate‐dependent subcritical cracking

Eppes

Keanini

2017

Reviews of Geophysics

204

150

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This work constructs a fracture mechanics framework for conceptualizing mechanical rock breakdown and consequent regolith production and erosion on the surface of Earth and other terrestrial bodies. Here our analysis of fracture mechanics literature explicitly establishes for the first time that all mechanical weathering in most rock types likely progresses by climate‐dependent subcritical cracking under virtually all Earth surface and near‐surface environmental conditions. We substantiate and quantify this finding through development of physically based subcritical cracking and rock erosion models founded in well‐vetted fracture mechanics and mechanical weathering, theory, and observation. The models show that subcritical cracking can culminate in significant rock fracture and erosion under commonly experienced environmental stress magnitudes that are significantly lower than rock critical strength. Our calculations also indicate that climate strongly influences subcritical cracking—and thus rock weathering rates—irrespective of the source of the stress (e.g., freezing, thermal cycling, and unloading). The climate dependence of subcritical cracking rates is due to the chemophysical processes acting to break bonds at crack tips experiencing these low stresses. We find that for any stress or combination of stresses lower than a rock's critical strength, linear increases in humidity lead to exponential acceleration of subcritical cracking and associated rock erosion. Our modeling also shows that these rates are sensitive to numerous other environment, rock, and mineral properties that are currently not well characterized. We propose that confining pressure from overlying soil or rock may serve to suppress subcritical cracking in near‐surface environments. These results are applicable to all weathering processes.

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Stress-induced Crack Path in Aji Granite under Tensile Stress

Cited by 2 publications

References 17 publications

Evolution of Elastic Wave Velocities and Amplitudes During Triaxial Deformation of Aji Granite Under Dry and Water‐Saturated Conditions

Evolution of Elastic Wave Velocities and Amplitudes During Triaxial Deformation of Aji Granite Under Dry and Water‐Saturated Conditions

Mechanical weathering and rock erosion by climate‐dependent subcritical cracking

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