Strain localization and cracking behavior of sandstone with two gypsum-infilled parallel flaws

Lei, Ruide; Zhang, Zhenyu; Berto, Filippo; Ranjith, P.G.; Zhang, Chengpeng

doi:10.1016/j.tafmec.2020.102873

Cited by 17 publications

(7 citation statements)

References 77 publications

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“…The flaw geometry parameters, including flaw length, wide, and ligament length are 14, 1.6, and 16 mm, as demonstrated in Figure 1. In order to facilitate the description, the specimen is named in a combination of letters and numbers, in which SN75‐45 is taken as an example, where S, N, 75, and 45 designate sandstone, non‐filled, inclination angle, and ligament angle, respectively 25,26 …”

Section: Materials and Setupmentioning

confidence: 99%

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Early‐warning signal recognition methods in flawed sandstone subjected to uniaxial compression

Lei

Berto

et al. 2022

Fatigue Fract Eng Mat Struct

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To investigate the precursor information related to rock fracturing, a series of indoor uniaxial compression tests are conducted on flawed sandstone. Four methods of identifying potential precursors to rock catastrophic failure, namely, cumulative acoustic emission (AE) activity, AE b-value, inter-event time function, and critical slowing down, are discussed. The results show that the four precursory identification methods can reasonably identify the earlywarning signal, subcritical failure, and final catastrophic failure of flawed sandstone involving the whole loading process. The minimum b-value is correspondingly obtained when the specimen approaches failure. The inter-event rate of AE multi-parameters shows a significant increase, following a power law distribution. By comparison with the other three precursor identification methods, the time intervals of AE parameters-based variance between the precursory signal and its corresponding tripping points become increasingly shortened. Additionally, the precursory characteristics of variance of AE multiparameters are more accurate and reliable than that of autocorrelation coefficient.

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Section: Materials and Setupmentioning

confidence: 99%

“…In order to facilitate the description, the specimen is named in a combination of letters and numbers, in which SN75-45 is taken as an example, where S, N, 75, and 45 designate sandstone, non-filled, inclination angle, and ligament angle, respectively. 25,26…”

Section: Specimen Description and Preparationmentioning

confidence: 99%

Early‐warning signal recognition methods in flawed sandstone subjected to uniaxial compression

Lei

Berto

et al. 2022

Fatigue Fract Eng Mat Struct

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“…Some filling materials, such as sand, clay, and broken rock fragments, are often present in the initial defects of the rock 1,3,21,22 . These filling materials change the friction coefficient at the bonding interface, which in turn affects the mechanical behavior around the defect 3,23,24 . On the other hand, engineering materials such as gypsum, cement, and concrete are often used for filling in many projects to reduce the stress concentration around the defect and to improve the integrity and stability of the rock mass 25,26 .…”

Section: Introductionmentioning

confidence: 99%

“…1,3,21,22 These filling materials change the friction coefficient at the bonding interface, which in turn affects the mechanical behavior around the defect. 3,23,24 On the other hand, engineering materials such as gypsum, cement, and concrete are often used for filling in many projects to reduce the stress concentration around the defect and to improve the integrity and stability of the rock mass. 25,26 Due to the presence of filling materials, the mechanical response and cracking behavior of rocks are more complicated.…”

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A novel quantitative explanation for the fracture mechanism of sandstone containing a circular inclusion

Zhang

Bao

et al. 2023

Fatigue Fract Eng Mat Struct

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In this study, uniaxial compressive tests combined with the digital image correlation (DIC) method are used to investigate the mechanical properties, fracture process, and failure pattern of sandstone containing a circular inclusion. A DIC‐based methodology is proposed to quantitatively explain the crack initiation and propagation mechanism. The identification criterion of crack type is presented based on the nature of cracks and the development trends of relative displacement. Three crack types, including tensile cracks, tensile–shear cracks, and shear cracks, with different cracking mechanisms are identified. The inhibitory effect of the inclusions on crack initiation and propagation is revealed. The inclusion–matrix debonding mechanism is further investigated, and it is found that the inclusion interface consists of tensile concentration zones on the left/right sides and compressive concentration zones on the top/bottom sides. The tensile concentration zone is the main reason for debonding of the inclusions from the sandstone matrix.

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“…Thanks to the acoustic emission (AE) technique in the laboratory, monitoring analyses can be conducted to observe the pre-failure microcrack accumulation [15][16][17][18][19][20][21][22][23][24] as well as to detect damage acceleration in brittle rocks consisting of pre-existing flaws [25][26][27][28][29][30][31]. Propagation and distribution of microcracks with increasing axial stress can be followed in rock samples by measuring the energy released.…”

Section: Introductionmentioning

confidence: 99%

Stress levels of precursory strain localization subsequent to the crack damage threshold in brittle rock

Göğüş

Avşar

2022

PLoS ONE

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Micromechanical cracking processes in rocks directly control macro mechanical responses under compressive stresses. Understanding these micro-scale observations has paramount importance in predicting macro-field problems encountered in rock engineering. Here, our study aims to investigate the development of precursory damage zones resulting from microcracking pertinent to macro-scale rock failure. A series of laboratory tests and three-dimensional (3D) numerical experiments are conducted on andesite samples to reveal the characteristics of damage zones in the form of strain fields. Our results from discrete element methodology (DEM) predict that the crack damage threshold (σcd) values are 61.50% and 67.44% of relevant peak stress under two different confining stresses (σ3 = 0.1 MPa and σ3 = 2 MPa), respectively. Our work evaluates the strain fields within the range of the σcd to the peak stress through discrete analysis for both confining stresses. We note that the representative strain field zones of failure are not observed as soon as the σcd is reached. Such localized zones develop approximately 88% of peak stress levels although the confinement value changes the precursory strain localization that appears at similar stress levels. Our results also show that the distinct strain field patterns developed prior to failure control the final size of the macro-damage zone as well as their orientation with respect to the loading direction (e.g 17° and 39°) at the post-failure stage. These findings help to account for many important aspects of precursory strain field analysis in rock mechanics where the damage was rarely quantified subtly.

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Strain localization and cracking behavior of sandstone with two gypsum-infilled parallel flaws

Cited by 17 publications

References 77 publications

Early‐warning signal recognition methods in flawed sandstone subjected to uniaxial compression

Early‐warning signal recognition methods in flawed sandstone subjected to uniaxial compression

A novel quantitative explanation for the fracture mechanism of sandstone containing a circular inclusion

Stress levels of precursory strain localization subsequent to the crack damage threshold in brittle rock

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