Development of stress-induced microcracks in Westerly Granite

Tapponnier, Paul; Brace, W. F.

doi:10.1016/0148-9062(76)91937-9

Cited by 709 publications

(286 citation statements)

References 18 publications

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“…Because failure begins by breaking the inter-granular bonds, the microstructure of a rock has a significant influence on the fracture progression behavior. Brittle fracturing of different rock types has been studied by many researchers (Brace et al 1966;Scholz 1968;Peng and Johnson 1972;Tapponnier and Brace 1976;Wong and Chau 1997;Eberhardt et al1999;Wong et al 2001;Alkan et al 2007;Wong and Wu 2014). While the majority of these studies tested intact rock, Ranjith et al (2004) used singly-and multiply-fractured granitic rock and characterized the behavior under uniaxial compression.…”

Section: Fracture Progression In Brittle Rockmentioning

confidence: 99%

Do joint geometrical properties influence the fracturing behaviour of jointed rock? An investigation through joint orientation

Wasantha

Ranjith

Zhang

et al. 2015

Geomech. Geophys. Geo-energ. Geo-resour.

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Failure of brittle rock is often progressive and understanding the fracture development process within rock masses is important to identify the precursors of failures. Joints in rock masses influence the fracture progression behavior and we studied the influence of joint orientation on fracture progression in jointed rock. Undrained triaxial tests were conducted on 54 mm diameter and 108 mm high intact and singly-jointed sandstone specimens. The joints in jointed specimens were made rough (joint roughness coefficient = 10-12) and embedded in six different orientations-0°, 30°, 45°, 60°, 75°and 90°-and three different combinations of confining and initial pore-water pressures were considered (confining pressure/pore-water pressure = 4/1, 10/4 and 25/10 MPa). An acoustic emission (AE) monitoring system was employed during all tests to monitor the fracture development within the test specimens. The post-failure patterns of specimens displayed three different failure mechanisms-shearing through intact material, sliding along the joint and a mixture of both shearing and sliding-depending on the joint orientation and confining pressure. The fracture progression behavior of the specimens showed a strong correlation with these failure mechanisms. Intact specimens and specimens with joints oriented at 0°, 30°, 90°failed by shearing. Nevertheless, the AE patterns of intact specimens and specimens with 90°-oriented joints contrasted with those of specimens with joints oriented at 0°a nd 30°. Specimens with joints oriented at 60°failed by sliding with a constant rate of acoustic event generation starting from the beginning of deviatoric loading. A mixed failure mechanism was observed for specimens with joints oriented at 45°and 75°. While the characteristics of both sliding and shearing failure were observed from the AE patterns of both 45°and 75°orientations, the shearing failure component of the 75°case was found to be a result of experimental limitations rather than real behavior. Finally, we propose a family of typical AE curves to assist with the characterization of the fracture progression behavior of jointed rock by taking confining pressures and failure mechanisms into consideration.

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Section: Fracture Progression In Brittle Rockmentioning

confidence: 99%

Do joint geometrical properties influence the fracturing behaviour of jointed rock? An investigation through joint orientation

Wasantha

Ranjith

Zhang

et al. 2015

Geomech. Geophys. Geo-energ. Geo-resour.

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“…Microcracks deform or close depending on their orientations. However, new cracks appear at preexisting intergranular at the onset of volume increase and then at 50-75% of peak stress new transgranular cracks appear [Tapponier and Brace, 1976;Fonseka et al, 1985]. The growth of microcracks is associated to mismatch of grain boundaries, differences in elastic moduli between minerals, intracrystalline flaws, and shear along grain boundaries [Taponnier and 8race, 1976].…”

Section: Introductionmentioning

confidence: 99%

Comparison of the microfracture localization in granite between fracturation and slip of a preexisting macroscopic healed joint by acoustic emission measurements

Jouinaux¹,

Masuda²,

Lei³

et al. 2001

J. Geophys. Res.

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“…Most of the cracking occurring before the peak stress appears to be intergranular (between grains). This is a departure from low-porosity crystalline rocks (granite) in which many of the cracks are intragranular [Tapponnier and Brace, 1976]. In sandstones it appears that most cracking occurs along grain boundaries, either by widening of preexisting microcracks or by shear rupturing of the cement at the grain contacts caused by rotation and slip of the grains.…”

mentioning

confidence: 98%

Micromechanical modeling of cracking and failure in brittle rocks

Hazzard¹,

Young²,

Maxwell³

2000

J. Geophys. Res.

245

108

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Abstract. Dynamic micromechanical models are used to analyze crack nucleation and propagation in brittle rock. Models of rock are created by bonding together thousands of individual particles at points of contact. The feasibility of using these bonded particle models to reproduce rock mechanical behavior is explored by comparing model behavior to results from actual laboratory tests on different rock types. The behavior of two granite models are examined in detail to study cracking and failure patterns that occur during compressional loading. Because discontinuum models are being used, the rock models are free to crack and break apart under stress, such that the micromechanics of cracking can be examined. Stress waves are allowed to propagate outward from each crack, and it is shown that these dynamic waves significantly affect the rock behavior. As the peak stress in the modeled rock is approached and many of the bonds are close to breaking, a passing wave from a nearby crack is sufficient to break more bonds. This causes clusters of cracks to be created, and then eventual macroscopic shear failure occurs as these clusters connect to bisect the sample. The failure patterns observed in the granite models are similar to those observed in actual laboratory tests. . These studies show that in sandstones, shear localization usually does not develop until after the peak stress has been reached. Most of the cracking occurring before the peak stress appears to be intergranular (between grains). This is a departure from low-porosity crystalline rocks (granite) in which many of the cracks are intragranular [Tapponnier and Brace, 1976]. In sandstones it appears that most cracking occurs along grain boundaries, either by widening of preexisting microcracks or by shear rupturing of the cement at the grain contacts caused by rotation and slip of the grains. The high level of acoustic emissions (AE) recorded during dilation gives evidence that this second process is occurring. 16,683

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Development of stress-induced microcracks in Westerly Granite

Cited by 709 publications

References 18 publications

Do joint geometrical properties influence the fracturing behaviour of jointed rock? An investigation through joint orientation

Do joint geometrical properties influence the fracturing behaviour of jointed rock? An investigation through joint orientation

Comparison of the microfracture localization in granite between fracturation and slip of a preexisting macroscopic healed joint by acoustic emission measurements

Micromechanical modeling of cracking and failure in brittle rocks

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