Influences of Loading Method and Notch Type on Rock Fracture Toughness Measurements: From the Perspectives of T-Stress and Fracture Process Zone

Wei, Mingdong; Dai, Feng; Liu, Yi; Li, Ang; Yan, Zelin

doi:10.1007/s00603-021-02541-9

Cited by 96 publications

(27 citation statements)

References 78 publications

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“…Studying and understanding the dynamic fracture characteristics of rocks under different loading rates are of great significance for the application of rock engineering and geophysics, and there are many researchers to make efforts in the fracture characteristics of rocks (Dai et al, 2016;Du et al, 2020;Du et al, 2021;Wei et al, 2021;Xia and Yao 2015).…”

Section: Introductionmentioning

confidence: 99%

“…So far, the research on rock dynamic fracture behaviors based on the NSCB method has mostly focused on the following aspects: 1) measurement of rock dynamic fracture toughness and crack propagation velocity, for example, Chen et al (2009) proposed a method to simultaneously measure dynamic fracture parameters such as fracture propagation toughness and fracture velocity using a semi-circular bend technique, and Zhao et al (2017) studied the influence of bedding angle and loading rate on the initiation fracture toughness of coal using NSCB method; 2) obtaining rock displacement and strain field using the digital image correlation (DIC) technology (Zhang and Zhao 2013;Zhang and Zhao 2014;Gao et al, 2015a;Gao et al, 2015b;Xing et al, 2017); 3) fracture characteristics of deep rock (Yin et al, 2014;Chen et al, 2016;Li et al, 2020), and 4) the influence of heat, moisture anisotropy, and other factors on rock dynamic fracture characteristics (Yin et al, 2012;Yao et al, 2017;Xu et al, 2018;Zhou et al, 2018;Cai et al, 2018;Wei, et al, 2018c;Shi et al, 2019;Cai et al, 2020a;Cai, et al, 2020b;Wei et al, 2021). Due to the limitation of the measurement technology, there is still a lack of in-depth understanding of the damage evolution law, energy evolution law, and mechanical mechanism of the failure mode in the deformation and the failure process of NSCB rock specimens.…”

Section: Introductionmentioning

confidence: 99%

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Numerical Simulation of Rock Dynamic NSCB Test Based on a Self-Developed Dynamic Damage Model

Duan

et al. 2022

Front. Earth Sci.

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Elucidating and understanding the dynamic fracture characteristics of rocks play an essential role in the application of rock engineering and geophysics. In this study, based on a self-developed dynamic damage model, a rock notched semi-circle bend test with the Split Hopkinson Pressure Bar technique is numerically simulated. The study focuses on three aspects including damage evolution, energy evolution, and failure mode of rock under different loading velocities. From the simulated results, the following conclusions can be conducted: 1) the damage range increases gradually with the increase of loading velocity; 2) the crack propagates to the loading point along the symmetry axis of the samples under different loading velocities; 3) the loading velocity has an important influence on the failure mode of straight notch semi-circular marble, whose mechanism can be explained by that the local high strain rate leads to the obvious randomness and uncertainty of crack activation in rock; and 4) the energy evolution of notched semi-circle bend is vitally affected by loading velocity, and the deformation and the failure process of straight notch semicircular marble under dynamic loading can be divided into five stages according to the ratio of internal energy to total energy. The beneficial findings may provide some references in practice design from engineering problems.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Numerical Simulation of Rock Dynamic NSCB Test Based on a Self-Developed Dynamic Damage Model

Duan

et al. 2022

Front. Earth Sci.

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“…However, with the help of a high‐precision cutting machine and a water‐jet cutting machine, many scholars make it possible to investigate the fracture mechanism of pre‐flawed rock material. The above studies mainly focus on the deformation, strength, and crack propagation with respect to joint inclination and rock bridge angle under static loading conditions 12–16 . In recent years, rock mass instability events resulting from the stress disturbance in civil and mining engineering emerge frequently, and many studies have paid attention to revealing the cyclic or fatigue mechanical behaviors of crack‐like rock 17–19 .…”

Section: Introductionmentioning

confidence: 99%

“…The above studies mainly focus on the deformation, strength, and crack propagation with respect to joint inclination and rock bridge angle under static loading conditions. [12][13][14][15][16] In recent years, rock mass instability events resulting from the stress disturbance in civil and mining engineering emerge frequently, and many studies have paid attention to revealing the cyclic or fatigue mechanical behaviors of crack-like rock. [17][18][19] In summary, the above studies have greatly broadened the understanding of the failure mechanism of jointed rock.…”

Section: Introductionmentioning

confidence: 99%

Insight into the fracture evolution behavior of pre‐flawed hollow‐cylinder granite under multi‐stage increasing‐amplitude cyclic loads: A lab‐scale testing

Wang

Yang

Han

et al. 2021

Fatigue Fract Eng Mat Struct

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The structural deterioration and associated fracture evolution behavior of preflawed hollow-cylinder granite subjected to multi-stage increasing-amplitude (MSIA) cyclic loads are studied herein. The influences of rock structure on volumetric deformation, damage accumulation, energy dissipation, and failure pattern were investigated. It is shown that the volumetric deformation is relatively large for rock having high flaw angle, and it is the minimum and maximum for rock having a 10 and 70 flaw angle. A damage evolution model that can describe a first fast and then steady damage propagation was proposed based on the irreversible axial strain. Much energy needs to be consumed to drive crack propagation and hole collapse for rock having high angle flaws. A series of 2D computed tomography (CT) images reveal the different crack network pattern and how it is affected by the rock structure. A more complicated crack network is found for rock having a high flaw angle.

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“…These studies were mainly carried out in the context of static or quasi-static loading conditions [22][23][24][25][26][27][28][29][30]. Most tri-axial unloading tests were used to study the influences of the unloading path on rock deformation, strength, and energy evolution after a freezing-thawing cycle [31][32][33][34][35][36][37][38]. However, the tri-axial unloading test cannot directly and effectively simulate the shear failure mechanism of rock that has suffered only from unloading normal stress.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Shear Mechanical Behavior of Sandstone with Unloading Normal Stress after Freezing–Thawing Cycles

Lian

Fei

et al. 2021

Machines

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Freezing–thawing action has a great impact on the physical and mechanical deterioration processes of rock materials in cold areas where environmental changes are very complicated. The direct shear test under unloading normal stress was adopted to investigate the shear mechanical behavior of sandstone samples after a freezing–thawing cycle in this paper. The failure shear displacement (Dsf), the failure normal displacement (Dnf), the shear displacement of unloading (Dsu), and the normal displacement of unloading (Dnu) were analyzed to describe the evolution of shear and normal deformation during the test. The results indicated that the shear displacement increased as the freezing–thawing cycle duration increased in a direct shear test under unloading normal stress. The unloading rate and the number of freezing–thawing cycles affected the failure pattern of the rock sample significantly in both the direct shear test under unloading normal stress and the direct shear test. The three-dimensional inclination angle, the distortion coefficient, and the roughness correlation coefficient of the fracture surface are dependent on the number of freezing–thawing cycles and the unloading rate. The surface average gradient mode of the fracture surface decreased as the freezing–thawing cycle times and unloading rate rose.

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Influences of Loading Method and Notch Type on Rock Fracture Toughness Measurements: From the Perspectives of T-Stress and Fracture Process Zone

Cited by 96 publications

References 78 publications

Numerical Simulation of Rock Dynamic NSCB Test Based on a Self-Developed Dynamic Damage Model

Numerical Simulation of Rock Dynamic NSCB Test Based on a Self-Developed Dynamic Damage Model

Insight into the fracture evolution behavior of pre‐flawed hollow‐cylinder granite under multi‐stage increasing‐amplitude cyclic loads: A lab‐scale testing

Investigation of the Shear Mechanical Behavior of Sandstone with Unloading Normal Stress after Freezing–Thawing Cycles

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