Electron scanning characteristics of rock materials under different loading methods: a review

Liu, Zelin; Ma, Chunde; Wei, Xiaojun

doi:10.1007/s40948-022-00392-4

Cited by 17 publications

(2 citation statements)

References 139 publications

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“…Previous studies indicate that microscopic morphological characteristics are related to crack initiation, crack propagation, and fracture modes [41]. To reveal the connection between them, the Scanning Electron Microscopic (SEM) technique was adopted to observe the morphological characteristics of typical failure fracture.…”

Section: Microscopic Characteristics Analysis In Typical Fracture Sur...mentioning

confidence: 99%

Mechanical Properties and Failure Behavior of Dry and Water-Saturated Foliated Phyllite under Uniaxial Compression

Wen

et al. 2022

Materials

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Phyllite is widely distributed in nature, and it deserves to be studied considering rock engineering applications. In this study, uniaxial compression tests were conducted on foliated phyllite with different foliation angles under dry and water-saturated conditions. The impacts of water content and foliation angle on the stress–strain curves and basic mechanical properties of the Phyllite were analyzed. The experimental results indicate that the peak stress and peak strain decrease first and then increase with increasing foliation angle as a U-shape or V-shape, and the phyllite specimens are weakened significantly by the presence of water. Moreover, an approach with acoustic emission, digital image correlation, and scanning electron microscopic is employed to observe and analyze the macroscopic and mesoscopic failure process. The results show that tensile microcracks dominate during the progressive failure of phyllite, and their initiation, propagation, and coalescence are the main reasons for the failure of the phyllite specimens. The water acts on biotite and clay minerals that are main components of phyllite, and it contributes to the initiation, propagation, and coalescence of numerous microcracks. Finally, four failure modes are classified as followed: (a) for the specimens with small foliation angles α = 0° or 30° (Saturated), both shear sliding and tensile-split across the foliation planes; (b) for the specimens with low to medium foliation angles α = 30° (Dry) or 45°(Saturated), shear sliding dominates the foliation planes; (c) for the specimens with medium to high foliation angles α = 45° (Dry) or 60°, shear sliding dominates the foliation planes; (d) for the specimens with high foliation angles α = 90°, tensile-split dominates the foliation planes.

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Section: Microscopic Characteristics Analysis In Typical Fracture Sur...mentioning

confidence: 99%

Mechanical Properties and Failure Behavior of Dry and Water-Saturated Foliated Phyllite under Uniaxial Compression

Wen

et al. 2022

Materials

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“…In addition, the higher the initial confining pressure, the more severe the failure of the specimen at the same unloading stress path, and the degree of rupture of the specimen becomes more complicated as the unloading rate increases [26]. The failure evolution characteristics vary for different types of rock [27][28][29]. For example, shale [27] exhibits obvious elastic-plastic characteristics under conventional triaxial compression tests, while it shows apparent elastic-brittle features under triaxial unloading tests, and the brittle failure characteristics increase with the increase of unloading rate and initial confining pressure.…”

Section: Introductionmentioning

confidence: 99%

Experimental Study on the Mechanical Characteristics of Saturated Granite under Conventional Triaxial Loading and Unloading Tests

Liu

2022

Sustainability

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It is essential to study the mechanical properties of saturated rock under different loading and unloading paths for strength calculation, safety assessment and disaster prevention; however, current literature rarely mentions conventional triaxial loading and unloading conditions. To analyze the mechanical properties, strain energy evolution characteristics and failure mode, a series of conventional triaxial unloading tests (with axial loading rate va of 0.06–6 mm/min and circumferential unloading rate vu of 0.1–10 MPa/s) and conventional triaxial compression tests were carried out on saturated granite. The test results showed that the damage sources of specimens in the conventional triaxial unloading test were mainly related to circumferential deformation, while in the conventional triaxial compression test, it was related to the axial deformation. Under the same va, the confining pressure and axial stress at the failure point decreased with the increase of vu, and the stress coordinate of the failure point was located outside the conventional triaxial compression envelope of σ1–σ3. As vu increases, except for the variation of circumferential strain energy DUc decreasing slowly, the trend of strain energy changes must be determined together with va. As va increases, the relationship between the magnitude of each energy changes from DUa > DU > DUd > DUe > DUc to DUd > DUa > DU > DUe > DUc, while the change of dissipated energy is dominated by vu and va together to become dominated by va. In addition, with the increase of vu and va, the damage pattern of the specimen also changes from shear damage in a single shear plane to mixed damage with tensile strain failure and shear plane during which the dilation angle of the specimen increases in total except for vu = 10 MPa/s, va = 0.6 mm/min and 6 mm/min.

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Fracture Mechanism of Sandstone Under Triaxial Extension at Different Loading Rates

Tan

et al. 2023

Rock Mech Rock Eng

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Electron scanning characteristics of rock materials under different loading methods: a review

Cited by 17 publications

References 139 publications

Mechanical Properties and Failure Behavior of Dry and Water-Saturated Foliated Phyllite under Uniaxial Compression

Mechanical Properties and Failure Behavior of Dry and Water-Saturated Foliated Phyllite under Uniaxial Compression

Experimental Study on the Mechanical Characteristics of Saturated Granite under Conventional Triaxial Loading and Unloading Tests

Fracture Mechanism of Sandstone Under Triaxial Extension at Different Loading Rates

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