Acoustic Emission and Failure Characteristics of Shales with Different Brittleness Under AWJ Impingement

Qu, Hai; Wu, Xiaoguang; Huang, Pengpeng; Tang, Shimao; Wang, Rui; Hu, Yushuang

doi:10.1007/s00603-021-02765-9

Cited by 10 publications

(3 citation statements)

References 44 publications

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“…AE technology, as a nondestructive testing technique, aims to characterize the fracture mechanism of coal–rock masses by detecting the elastic waves released during the deformation and propagation of cracks within the material under stress. , Monitoring the characteristic parameters of internal damage within samples during the loading and unloading processes allow for the derivation of ring counts and cumulative energy features of the samples (Figure ), thereby providing insights into the material’s behavior. The ring count refers to the number of times the AE signal exceeds a predetermined threshold, serving as an acoustic reflection of the evolution of the internal structure within the sample, while the energy indicates the energy released by crack expansion inside the sample per unit time. , …”

Section: Results Analysis and Discussionmentioning

confidence: 99%

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Deformation and Failure Characteristics of Strong–Weak Coupling Structures with Different Height Ratios Under Cyclic Loading and Unloading

Chen,

Zhai,

et al. 2024

ACS Omega

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Strong−weak coupling outburst prevention technology can reduce the hazard of coal and gas outburst in mines based on hydraulic punching and grouting reinforcement. In this study, the mechanism of outburst hazards in the strong−weak coupling structure under mining disturbance was explored, and then cyclic loading and unloading experiments were performed on samples with different strong−weak height ratios (HRs) using the noncontact full-field strain testing (DIC) system and the acoustic emission (AE) system. The results show that the failure strength of the sample gradually increases with the increase in HR. The residual strain of the strong and weak structures undergoes three stages, i.e., the decelerated deformation, the constant-velocity deformation, and the accelerated deformation. Deformation mainly occurs in the weak structure and starts at the strong−weak interface. The AE signals present strong regional distribution characteristics and the Felicity effect, and the damage is concentrated near 70% of each stage in the cyclic loading process. As the HR rises, the weak structure transitions from brittle damage to ductile damage and from shear damage to tensile damage. In addition, due to the difference in Poisson effects of strong and weak structures, the strong structure transitions from a unidirectional stress state to a triaxial tensile−compressive stress state. When the HR increases to 85:15, the strong structure undergoes tensile damage.

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Section: Results Analysis and Discussionmentioning

confidence: 99%

“…The ring count refers to the number of times the AE signal exceeds a predetermined threshold, serving as an acoustic reflection of the evolution of the internal structure within the sample, while the energy indicates the energy released by crack expansion inside the sample per unit time. 40 , 41 …”

Section: Results Analysis and Discussionmentioning

confidence: 99%

Deformation and Failure Characteristics of Strong–Weak Coupling Structures with Different Height Ratios Under Cyclic Loading and Unloading

Chen,

Zhai,

et al. 2024

ACS Omega

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“…Brittleness Index (BI) has been recognized as one of the key parameters controlling fracture development in geo-materials during reservoir stimulation, [1][2][3][4][5] fluid-induced seismicity, [6][7][8] and magma migration. 9 However, the definition and quantification of a reliable BI for hydromechanical applications remains a challenge, i.e., the existing BI models are mainly based on rock mechanical parameters but neglect the coupled hydro-mechanical interactions associated with rock deformation at depth.…”

Section: Introductionmentioning

confidence: 99%

Laboratory validation of a new hydro-mechanical energy-based brittleness index model for hydraulic fracturing

Feng¹,

Sarout²,

Dautriat³

et al. 2022

Preprint

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Brittleness Index (BI) is a critical parameter characterising the deformation regime of geo-materials, covering the range from purely brittle (fractures) to ductile (plastic flow). A variety of BI models have been developed based on rock properties such as mineralogy, elastic parameters, or stress-strain data. However, very few of them are based on the deformation induced by hydro-mechanical interactions emerging in a wide range of underground engineering applications. In this study, we develop a BI model based on the partitioning of the injection energy EI into non-seismic deformation energy Ed associated with hydraulic fracture propagation. To calculate the Ed, we apply a model for temporal fracturing area (Ad) within the penny-shaped fracture; we also correlate the wellbore pressure and the three-dimensional strain induced by hydraulic fracturing of the different types of rock samples subjected to true triaxial stress conditions (TTSC), either σv = 6.5 MPa, σH = 3 MPa, σh = 1.5 MPa or σv = 15 MPa, σH = 10 MPa, σh = 5 MPa for all tests. As a comparison, the BI is also quantified based on the existing models: (i) acoustic measurement from Rickman et al (2008), and (ii) the Mohr-Coulomb’s criteria from Papanastasiou et al (2016). The non-seismic deformation energy Ed ranges between 32.4% and 90.6% of the total injection energy EI, which is slightly higher than reported from field-scale data (15% to 80%), and is comparable to other laboratory-derived data (18% to 94%). The results show that the predictions based on our newly proposed hydro-mechanical energy-based BI model are qualitatively consistent with Papanastasiou et al.’s, but less so with Rickman et al.’s. Our BI model is shown to be stress-dependent and capable of capturing the brittle-to-ductile behaviour within a wide range of rheological samples subjected to hydraulic fracturing. This study demonstrates that our BI model opens a new way for quantifying the brittleness index regarding to realistic propagation scenarios, showing its superior robustness for such underground applications.

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Micromechanics of Fracture Propagation During Multistage Stress Relaxation and Creep in Brittle Rocks

Zafar

Hedayat²,

Moradian³

2022

Rock Mech Rock Eng

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Acoustic Emission and Failure Characteristics of Shales with Different Brittleness Under AWJ Impingement

Cited by 10 publications

References 44 publications

Deformation and Failure Characteristics of Strong–Weak Coupling Structures with Different Height Ratios Under Cyclic Loading and Unloading

Deformation and Failure Characteristics of Strong–Weak Coupling Structures with Different Height Ratios Under Cyclic Loading and Unloading

Laboratory validation of a new hydro-mechanical energy-based brittleness index model for hydraulic fracturing

Micromechanics of Fracture Propagation During Multistage Stress Relaxation and Creep in Brittle Rocks

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