Effects of water intrusion and loading rate on mechanical properties of and crack propagation in coal–rock combinations

Chen, Tian; Yao, Qiangling; Wei, Fei; Chong, Zhaohui; Zhou, Jian; Wang, Changbin; Li, Jing

doi:10.1007/s11771-017-3444-6

Cited by 46 publications

(20 citation statements)

References 28 publications

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“…19,20 With the help of the cumulative AE counts, these curves complement and confirm each other. At point E, indicating peak shear strength, the coal sample is mechanically ineffective, and shear stiffness is lowest.…”

Section: Effect Of Fracture On Cumulative Acoustic Emission Counts supporting

confidence: 53%

“…The shear stiffness-shear stress curve corresponds well with the shear displacement-shear stress curve, which shows every stage of crack development before the coal sample fails. 19,20 With the help of the cumulative AE counts, these curves complement and confirm each other. Figure 8 shows that the stress threshold has an approximately linear relationship with the water content.…”

Section: Effect Of Fracture On Cumulative Acoustic Emission Counts supporting

confidence: 53%

“…Differences in the structural components of coal and rock masses lead to different regularities in the mechanical properties of coal and rock after water absorption. 18 This technology can also obtain the thresholds of each stage 19,20 and classify crack types. 14 Shear failure is a common failure form in engineering.…”

mentioning

confidence: 99%

“…15 Acoustic emission (AE) technology has been used to nondestructively detect cracks and assess damage 16,17 and may be used to divide the crack development process in brittle materials into five stages: crack closure, elastic deformation, stable crack development, unstable crack development, and the postpeak stage. 18 This technology can also obtain the thresholds of each stage 19,20 and classify crack types. 21 In addition, high-resolution three-dimensional (3D) X-ray microscopy (3D-XRM) or computed tomography of rock offers another route to study the internal pore and crack distribution in rock materials and solid waste.…”

mentioning

confidence: 99%

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Experimental study of shear failure and crack propagation in water‐bearing coal samples

Tang

Yao

et al. 2019

Energy Science & Engineering

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The design of dam bodies for underground reservoirs must account for how water affects shear failure and the evolution of fractures in coal pillars. In this work, we detect acoustic emissions in raw coal samples with different water content (0%, 5.35%, 17.88%, and 20.40%) and under uniaxial compression shear and use computed tomography to analyze the failed samples. The results show that the shear strength, shear displacement, cohesion, and internal friction angle all decrease with increasing water content, which is described by the revised Mohr‐Coulomb model for the case of water intrusion. The acoustic emission counts correlate strongly with the change in stress, and the cumulative acoustic emission counts are combined with shear stiffness to separate the fracture evolution process into five stages: crack closure, elastic deformation, stable crack propagation, unstable crack propagation, and failure. The ratios of the crack closure, initiation, and damage stress to the corresponding peak shear stress are essentially unaffected by the water content. Most cracks are tensile cracks, and an increase in the water content promotes the development of parallel fractures. These results are helpful for determining the size of coal pillars in underground reservoirs and for solving other underground engineering problems, such as support for water‐rich coal roadways.

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Section: Effect Of Fracture On Cumulative Acoustic Emission Counts supporting

confidence: 53%

Section: Effect Of Fracture On Cumulative Acoustic Emission Counts supporting

confidence: 53%

mentioning

confidence: 99%

mentioning

confidence: 99%

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Experimental study of shear failure and crack propagation in water‐bearing coal samples

Tang

Yao

et al. 2019

Energy Science & Engineering

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“…Acoustic emission (AE) monitoring is a useful technique to capture the failure process of rocks [13,14]. Many researchers [15][16][17][18][19] analyzing the mechanical properties of coal and rock with different water content combined acoustic emission data. Previous results have shown that there is a negative relation between the acoustic emission count and water content, and the increasing moisture content promotes creep damage in coal and rock.…”

Section: Introductionmentioning

confidence: 99%

Effects of Water-Soaking Height on the Deformation and Failure of Coal in Uniaxial Compression

et al. 2019

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The stability of water-preventing coal pillar plays an important role in preventing gob water inrush. The gob side of the water-preventing coal pillar is soaked in a certain height of mine water. Different soaking heights may affect the stability of coal pillars. Few studies have been conducted on the properties of coals with different water-soaking heights. We carried out uniaxial compressive tests on coal specimens with different water-soaking heights to gain a better understanding of different water-soaking-height-induced weakening characteristics of coal. Results show that: (1) The water content of coal specimens increases with the soaking height. Water significantly weakens the strength of coal specimens. However, the extent of strength weakening of the coal specimen does not increase with the increase of the soaked height. The strength of the fully soaked coal specimen is lowest among all groups of coal specimens. The strength of the three groups of partially soaked coal specimens is between the fully soaked coal specimens and the coal specimens without being soaked in the water. In the three groups of partially soaked coal specimens, the strength of the coal specimens increases with the increase of the soaking height. (2) The acoustic emission activities of complete water soaking and nonsoaking coal specimens are relatively concentrated, occurring mainly in unstable fracture expansion stage and post-peak destruction stage, and acoustic emission exhibits main-shock mode. Partially soaking coal specimens, especially the 25% water-soaking height and 50% water-soaking height coal specimens, produces obvious acoustic emission activities during the fracture expansion stabilization phase, and then generates more acoustic emission activities during the unstable expansion stage and the post-peak stage. The acoustic emission presents foreshock-main shock mode. (3) The softening effect of the water soaking on the coal specimens is obvious. It was further found that the deformation of coal specimens with partial water soaking is not synchronized in different layers, the nonuniform deformations of partially soaked coal specimens aggravate its damage.

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Influence of Loading Rate on the Failure Characteristics of Composite Coal–Rock Specimens Under Quasi-static Loading Conditions

et al. 2021

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Effects of water intrusion and loading rate on mechanical properties of and crack propagation in coal–rock combinations

Cited by 46 publications

References 28 publications

Experimental study of shear failure and crack propagation in water‐bearing coal samples

Experimental study of shear failure and crack propagation in water‐bearing coal samples

Effects of Water-Soaking Height on the Deformation and Failure of Coal in Uniaxial Compression

Influence of Loading Rate on the Failure Characteristics of Composite Coal–Rock Specimens Under Quasi-static Loading Conditions

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