Strength and anisotropy of foliated rocks with varied mica contents

Shea, William T.; Kronenberg, A. K.

doi:10.1016/0191-8141(93)90158-7

Cited by 229 publications

(148 citation statements)

References 48 publications

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“…For example, the rock mechanical properties may be affected by other factors. As the study carried out by Shea et al [49], the influence of micas on the strength and anisotropy of foliated rocks turned out to be very obvious. In fact, the failure mode of foliated rocks could be brittle, transitional and ductile shear according to varied mica contents.…”

Section: Of 24mentioning

confidence: 98%

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

et al. 2016

Energies

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Abstract:With the exploitation of shale gas booming all over the world, more and more studies are focused on the core technology, hydraulic fracturing, to improve commercial exploitation. Shale gas resources in China are enormous. In this research, a series of tests were carried out with samples of black organic-rich shale from the Lower Silurian Longmaxi formation, south China. Samples were drilled from different directions and were subjected to uniaxial and triaxial condition with various confining pressures, aiming at studying its rock mechanics properties, so as to provide basis for research and breakthrough of hydraulic fracturing technology. According to the results of the study, the development and distribution of shale's bedding planes significantly impact its mechanical properties. Shale samples show obvious brittle characteristics under low confining pressure, and its mechanical behavior begins to transform from brittle to plastic characteristics with increasing confining pressure. Shale samples with different inclinations (β) have different sensitivities to the confining pressure. As a result, samples with 45 • inclinations (β) are least sensitive. The strength of bedding planes is significantly lower than that of shale matrix, and tensile failure and shear failure generally tend to occur along the bedding planes. When hydraulic fracturing was conducted in shale formation with depth less than 2.25 km, corresponding to original in-situ of 60 MPa, cracks will preferably occur at first along the inclination (β) angle of 45 • from the maximum principal stress, and the failure mode is most likely to be shear failure without volumetric strain. And, different modes of failure will occur at different locations in the reservoir, depending on the orientation of bedding inclined from the principle stress, which can probably explain the phenomenon why there are fractures along and cross the bedding planes during hydraulic fracturing treatment. When hydraulic fracturing was conducted in shale formation with depth greater than 2.25 km, hydraulic fractures may not crack along the bedding surfaces to some extent.

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Section: Of 24mentioning

confidence: 98%

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

et al. 2016

Energies

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“…Measured strength parameters depend not only on the modal mineralogy but also on texture and anisotropy [8].…”

Section: Rock Mechanical Testingmentioning

confidence: 99%

Testing of Ore Comminution Behavior in the Geometallurgical Context—A Review

2015

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Abstract:Comminution tests are an important element in the proper design of ore beneficiation plants. In the past, test work has been conducted for particular representative reference samples. Within geometallurgy the entire ore body is explored in order to further identify the variation within the resource and to establish spatial geometallurgical domains that show the differential response to mineral processing. Setting up a geometallurgical program for an ore deposit requires extensive test work. Methods for testing the comminution behavior must therefore be more efficient in terms of time and cost but also with respect to sample requirements. The integration of the test method into the geometallurgical modeling framework is also important. This paper provides an overview of standard comminution test methods used for the investigation of ore comminution behavior and evaluates their applicability and potential in the geometallurgical context. Keywords: geometallurgy; comminution behavior; metallurgical testing BackgroundBefore concentration, metal ores have to be crushed and ground in order for the metal bearing minerals to be liberated. Sufficient size reduction by comminution is not only a prerequisite for any downstream physical separation, but is also the processing step within mineral processing that has the highest energy demand, and which, in practice, is often the limiting factor for plant capacity. Reliable OPEN ACCESS

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“…2.1C). According to Balla et al (2009) (Shea et al, 1993). The MZ is a zone of intense mylonitic shear (Lelkes-Felváry et al, 2000;M.…”

Section: The Mecsekalja Zone (óFalu Group)mentioning

confidence: 99%

“…Previous triaxial and uniaxial tests of transversely anisotropic crystalline rocks have been carried out by Gottschalk et al (1990), Shea et al (1993) and Rawling et al (2002) to reveal the principles of microcrack evolution caused by stressing. The experiments of Shea et al (1993) have proven the fundamentally important role of biotite (and generally mica) on the formation of microcracks in transversely foliated crystalline rocks. In the studied samples, the microcrack calcite has varying textural appearance and in some samples, it is not luminescent.…”

Section: Texture Of the Studied Samples And Cathodoluminescent Imagesmentioning

confidence: 99%

“…The closure of the initial microcrack system at the onset of stressing of the rock is a characteristic feature of stress-strain diagrams (Cai, 2009), even in crystalline rocks with very low porosity (Zoback and Byerlee, 1975a;Lajtai, 1998). During further increase of stress, the formation 75 of microcrack populations start at the crack initiation stress and continues until strain localisation occurs in the sample and macroscopic failure occurs (Gottschalk et al, 1990;Shea et al, 1993;Rawling et al 2002). It is obvious that the process of microcrack formation implies a very sensitive interaction between fluid properties and deformation in a crustal volume saturated with fluids, i.e., the increase of the quantity of pore fluids during dilatancy and microcrack formation, or the increase of fluid pressure during microcrack closure.…”

Section: Introductionmentioning

confidence: 99%

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Post-metamorphic palaeofluid evolution of the Mecsekalja Zone metamorphic complex

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Strength and anisotropy of foliated rocks with varied mica contents

Cited by 229 publications

References 48 publications

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States

Testing of Ore Comminution Behavior in the Geometallurgical Context—A Review

Post-metamorphic palaeofluid evolution of the Mecsekalja Zone metamorphic complex

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