On Tension Failure of 2-D Rock Specimens and Associated Acoustic Emission

Tham, L.G.; Liu, H.; Tang, Chun An; Lee, P. K. K.; Tsui, Y

doi:10.1007/s00603-004-0031-6

Cited by 75 publications

(25 citation statements)

References 11 publications

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“…The corresponding strength is almost equal to the rock tensile strength [15]. Once a microcrack occurs in tensile experiments in brittle rocks, the crack will propagate unstably [16], which shows that the rock tensile testing results agree with the fracture characteristics in shale hydraulic fracturing. Therefore, this paper overcomes the limitation of using the prepeak mechanical parameters and postpeak stress attenuation degree to represent rock brittleness, proposes the definition of the brittleness index based on tensile failure, presents a comprehensive evaluation method and prediction model, and forms a theoretical system for evaluating shale brittleness under tensile conditions.…”

Section: Introductionsupporting

confidence: 69%

Brittleness Evaluation of Shale Based on the Brazilian Splitting Test

et al. 2018

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Brittleness is an important mechanical parameter of shale reservoirs and has a significant effect on hydraulic fracturing. Traditional evaluation methods of shale brittleness are mainly based on complete stress-strain curves under compressive loading, which can barely describe the fracture characteristics of shale during hydraulic fracturing. This paper proposes to define the brittleness index based on the Brazilian splitting test and establishes a corresponding evaluation method, forming a tensile brittleness evaluation system for noncontinuous shale. The Brazilian splitting test and discrete element numerical simulation are carried out to study the crack distribution characteristics after tensile failure as well as the influence of anisotropy and scale effect on the brittleness of shale. The results show that the tensile brittleness index is more accurate and sensitive to condition changes than the compressive brittleness index. The experimental shale cores are from the Longmaxi formation, Silurian system, Sichuan basin.

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Section: Introductionsupporting

confidence: 69%

Brittleness Evaluation of Shale Based on the Brazilian Splitting Test

et al. 2018

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“…As it is well known, Acoustic Emission (AE) technique is an efficient measuring tool to reflect the evolution and propagation of defects in materials, which has been widely applied to investigate the damage and fracture behavior internal the rock material in many past studies (Li et al 2005;Labuz et al 2001;Chang and Lee 2004;Moradian et al 2010;Pestman and Van Munster 1996;Debecker and Vervoort 2009;Ganne and Vervoort 2007;Eberhardt et al 1999;Tham et al 2005;Jouniaux et al 2001). Debecker and Vervoort (2009) carried out a series of Brazilian tensile tests and uniaxial compression tests for layered slate by visual recordings and AE technique, which investigated in detail the fracture sequence and growth direction in anisotropic slate samples.…”

Section: Introductionmentioning

confidence: 99%

“…Eberhardt et al (1999) analyzed the influence of grain size on the initiation and propagation thresholds of stress-induced brittle fractures by AE monitoring. Tham et al (2005) characterized the micro-and macro-failure behaviors of granite and marble plate samples under uniaxial tension by using an AE technique. The results reveal clearly the failure processes of rock including initiation, nucleation and propagation of micro-fractures when the axial stress is close to the peak strength of rock.…”

Section: Introductionmentioning

confidence: 99%

Strength failure and crack coalescence behavior of brittle sandstone samples containing a single fissure under uniaxial compression

2010

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Uniaxial compression experiments were performed for brittle sandstone samples containing a single fissure by a rock mechanics servo-controlled testing system. Based on the experimental results of axial stress-axial strain curves, the influence of single fissure geometry on the strength and deformation behavior of sandstone samples is analyzed in detail. Compared with the intact sandstone sample, the sandstone samples containing a single fissure show the localization deformation failure. The uniaxial compressive strength, Young's modulus and peak axial strain of sandstone samples with pre-existing single fissure are all lower than that of intact sandstone sample, which is closely related to the fissure length and fissure angle. The crack coalescence was observed and characterized from tips of pre-existing single fissure in brittle sandstone sample. Nine different crack types are identified based on their geometry and crack propagation mechanism (tensile, shear, lateral crack, far-field crack and surface spalling) for single fissure, which can be used to analyze the failure mode and cracking process of sandstone sample containing a single fissure under uniaxial compression. To confirm the subsequence of crack coalescence in sandstone sample, the photographic monitoring and acoustic emission (AE) technique were adopted for uniaxial compression test. The real-time crack coalescence process of sandstone containing a single fissure was recorded during the whole loading. In the end, the influence of the crack coalescence on the strength and deformation failure behavior of brittle sandstone sample containing a single fissure is analyzed under uniaxial compression. The present research is helpful to understand the failure behavior and fracture mechanism of engineering rock mass (such as slope instability and underground rock burst).

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“…The limestone specimens were small, with dimensions of 15 9 30 9 3 mm. The acoustic emission (AE) technique has been widely applied in many past studies to investigate the damage and fracture behaviour of internal brittle rock material, but the AE technique was less often used to explore the crack coalescence of brittle rock containing pre-existing fissures under uniaxial compression (Chang and Lee 2004;Debecker and Vervoort 2009;Tham et al 2005). Yang and Jing (2011) conducted uniaxial compression experiments with brittle sandstone specimens of dimensions 60 9 120 9 30 mm and containing a single fissure to investigate the influences of fissure length and angle on the strength and deformation failure behaviour of specimens by using photographic monitoring and AE techniques.…”

Section: Introductionmentioning

confidence: 99%

An Experimental Study of the Fracture Coalescence Behaviour of Brittle Sandstone Specimens Containing Three Fissures

et al. 2011

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To analyse the fracture coalescence behaviour of rock, rectangular prismatic sandstone specimens (80 9 160 9 30 mm in size) containing three fissures were tested under uniaxial compression. The strength and deformation behaviours of the specimens are first analysed by investigating the effects of the ligament angle b 2 on the peak strength, peak strain and crack initiation stress of the specimens. To confirm the sequence of crack coalescence, a photographic monitoring technique is used throughout the entire period of deformation. Based on the results, the relationship between the real-time crack coalescence process and the axial stress-strain curve of brittle sandstone specimens is also developed, and this relationship can be used to evaluate the macroscopic deformation characteristics of pre-cracked rock. The equivalent strain evolution fields of the specimen, with a = b 1 = 45°and b 2 = 90°, are obtained using the digital image correlation technique and show good agreement with the experimental results of pre-cracked brittle sandstone. These experimental results are expected to improve the understanding of fracture mechanisms and be used in rock engineering with intermittent structures, such as deep underground excavated tunnels.

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On Tension Failure of 2-D Rock Specimens and Associated Acoustic Emission

Cited by 75 publications

References 11 publications

Brittleness Evaluation of Shale Based on the Brazilian Splitting Test

Brittleness Evaluation of Shale Based on the Brazilian Splitting Test

Strength failure and crack coalescence behavior of brittle sandstone samples containing a single fissure under uniaxial compression

An Experimental Study of the Fracture Coalescence Behaviour of Brittle Sandstone Specimens Containing Three Fissures

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