Evolution of Rock Cracks Under Unloading Condition

Huang, Runqiu; Huang, Da

doi:10.1007/s00603-013-0429-0

Cited by 86 publications

(24 citation statements)

References 12 publications

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“…In natural rocks, preexisting flaws usually appear in sets or groups with similar orientations and characteristics but with a remarkable length discrepancy. For example, multiple sets of well‐developed tectonic fractures with the length discrepancy exist in the surrounding rock of power house in the right bank of the Three Gorges Project . These fractures, which are approximately parallel to the axis of power house (axis azimuth 43.5°), likely form local weak zones by the coalescence of preexisting joints and, thus, endanger the mother rock mass .…”

Section: Introductionmentioning

confidence: 99%

“…20 These fractures, which are approximately parallel to the axis of power house (axis azimuth 43.5°), likely form local weak zones by the coalescence of preexisting joints and, thus, endanger the mother rock mass. 20 It is noticed that the crack evolution mechanisms from non-isometric flaws are rarely studied, and the related interactions between non-isometric flaws are not understood fully. Reasonably, the roles of the relatively long preexisting flaws in rock failure appear to be distinguishable or even radically different from the short flaws.…”

Section: Introductionmentioning

confidence: 99%

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Progressive failure of brittle rocks with non‐isometric flaws: Insights from acousto‐optic‐mechanical (AOM) data

Zhang

Zhou

et al. 2019

Fatigue Fract Eng Mat Struct

107

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Uniaxial compression tests combined with nondestructive testing techniques are performed to explore the roles of non‐isometric flaws in crack developments in brittle rocks. The acoustic emission (AE) rate‐process theory is adopted to analyze fracture‐related AE event rate characteristics. The full‐field optical method is applied to detect cracking modes. Experimental results show that AE activity is quite active when the matrix microcracking is dominant, while after each macrocracking event, AE activity becomes inactive because of the stress release. Multiphysical data for each tested flaw configuration faithfully confirm the rupture progressivity. The larger the flaw length ratio, the lower the peak stress (also peak axial strain and elastic modulus), as well as the more progressive the cracking process. Moreover, ultimate failure is triggered by the shear fracturing from the relatively long flaw. The short flaw is conditionally involved in ultimate failure when the stress buildup effect dominates. Finally, the fracture mechanism of brittle rocks with non‐isometric flaws is revealed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Progressive failure of brittle rocks with non‐isometric flaws: Insights from acousto‐optic‐mechanical (AOM) data

Zhang

Zhou

et al. 2019

Fatigue Fract Eng Mat Struct

107

View full text Add to dashboard Cite

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“…Confining pressure unloading leads to an increase in tensile stress near the tip of micro cracks inside the rock samples and decrease in shear strength. Thus the potential of tensile and shear developments in rock increase (Huang and Huang 2014). With the increasing unloading rates of the confining pressure and chemical effects, stable crack development transforms relatively quickly into unstable crack development, degrading the peak strength of the limestone sample.…”

Section: The Relationship Between the Mechanical Behavior And The Micmentioning

confidence: 99%

Experimental Investigation of the Permeability and Mechanical Behaviours of Chemically Corroded Limestone Under Different Unloading Conditions

Zhong

Eshiet³

et al. 2019

Rock Mech Rock Eng

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This paper investigates the mechanical properties and permeability of chemically corroded rock during deep underground tunneling. Nuclear magnetic resonance tests are carried out to quantify the chemical damage of limestone samples at the microscopic scale. Coupled hydrostatic pressure-unloading tests at different unloading rates are also conducted on these chemically corroded limestone samples to investigate permeability changes and chemical effects on mechanical behaviours. Magnetic resonance imaging, T 2 spectrum distribution and porosity of the samples are obtained, and the chemical micro damage is visualized and quantified. The relationship between permeability and mechanical behaviors of the rock under hydrochemical-mechanical coupled effects is investigated. The results show that the permeability development process of the chemical corroded samples can be divided into three stages: at the first stage, the permeability initially decreases, and the second stage starts at the inflection point of the permeability curve, from where the permeability begins to increase slightly. At the third stage, the permeability of the limestone increases dramatically until the sample is ruptured. Chemical corrosion and unloading rates have a combined and significant influence on the development of micro cracks in rocks, which is the root cause of the permeability changes. A stress-permeability model is proposed to describe the permeability and stresses in chemical-corroded limestone; this can be adopted for other sedimentary rocks.

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“…erefore, there is an urgent need to investigate the mechanical behavior of coal and rock during the unloading process. To date, researchers have analyzed various factors affecting the unloading mechanical behaviors of coal and rock, including the unloading path, unloading rate [9,10], and initial unloading confining pressure [11,12]; many significant results have been obtained [13][14][15].…”

Section: Introductionmentioning

confidence: 99%

Fractal Characteristics of Coal and Sandstone Failure under Different Unloading Confining Pressure Tests

Yang

2020

Advances in Materials Science and Engineering

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To analyze the fractal characteristics of coal rock failure under unloading conditions, triaxial unloading confining pressure tests were carried out on coal and sandstone rock samples under different unloading rates and initial confining pressures. We examined the distribution of the surface cracks and fragmentation of the coal and sandstone samples that failed under different triaxial unloading confining pressure tests. The results showed that the fractal dimension of the surface cracks in coal and sandstone decreased as the initial unloading confining pressure increased. Thus, shear failure is more obvious in coal or sandstone with high-stress conditions caused by unloading confining pressure than in coal or sandstone with low-stress conditions. However, the fractal dimension of the surface cracks increased with the unloading rates. Additionally, the fractal dimension of the fragmentation in the coal and sandstone samples had a negative correlation with the initial unloading confining pressure. When the initial confining pressure was relatively low, the samples underwent splitting and shear failure; when the initial confining pressure was higher, the failure mode was mostly shear failure and the fragmentation of the samples was less homogeneous. In contrast, the fractal dimension of the fragmentation in the coal and sandstone increased with higher unloading rates. The lithology had a significant effect on the fractal dimension of the surface cracks and on the fragmentation. Samples with more internal fissures had more surface cracks and the fragmentation was more homogeneous when the rock failed compared with samples with less fissures under the same experimental conditions.

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Evolution of Rock Cracks Under Unloading Condition

Cited by 86 publications

References 12 publications

Progressive failure of brittle rocks with non‐isometric flaws: Insights from acousto‐optic‐mechanical (AOM) data

Progressive failure of brittle rocks with non‐isometric flaws: Insights from acousto‐optic‐mechanical (AOM) data

Experimental Investigation of the Permeability and Mechanical Behaviours of Chemically Corroded Limestone Under Different Unloading Conditions

Fractal Characteristics of Coal and Sandstone Failure under Different Unloading Confining Pressure Tests

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