Experimental and theoretical study of the anisotropic properties of shale

Heng, Shuai; Guo, Yingtong; Yang, Chunhe; Daemen, J.J.K.; Li, Zhi

doi:10.1016/j.ijrmms.2015.01.003

Cited by 182 publications

(61 citation statements)

References 47 publications

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“…The error between the two methods was put forward: Zhang noted that the strength parameters obtained by triaxial compression test were higher than that by direct shear test. The strength parameters could be determined by triaxial compression test while the direct shear test is also feasible . Based on the above research results and existing test data, the triaxial test data were used to determine the elastoplastic equation in the following paragraph.…”

Section: Improved Mechanical Model For Layered Rocks Incorporating Vomentioning

confidence: 99%

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Anisotropic modeling of layered rocks incorporating planes of weakness and volumetric stress

Tan

Zhou

et al. 2019

Energy Science & Engineering

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Layered rocks exhibit notable transverse isotropy and have a significant impact on the deformation and failure characteristics of underground structures. To a large extent, the mechanical properties of layered rocks are related to the structure and stress state of their bedding planes. To obtain an in‐depth understanding of the deformation and yield characteristics of layered rocks, a mechanical model for layered rocks incorporating planes of weakness and volumetric stress is proposed by improving the strain‐hardening/softening ubiquitous‐joint model based on continuum mechanics methods. In this mechanical model, elastoplastic equations for the matrix and bedding planes of layered rocks are established. The evolution of the mechanical parameters of the matrix and bedding planes of layered rocks with the internal variable is determined. In addition, the sensitivity of the model parameters is analyzed, and a method for determining the parameters is provided to reduce the complexity in obtaining these parameters. The numerical calculation results for the laboratory tests on layered sandstone specimens under various stress levels agree relatively well with the test results, thereby validating the effectiveness of the improved model. The methods and results of this study provide a significant reference for the analysis of the deformation and failure of other layered rocks.

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Section: Improved Mechanical Model For Layered Rocks Incorporating Vomentioning

confidence: 99%

“…The strength parameters could be determined by triaxial compression test 34 while the direct shear test is also feasible. 35,36 Based on the above research results and existing test data, the triaxial test data were used to determine the elastoplastic equation in the following paragraph.…”

Section: Elastoplastic Equation For the Bedding Planes Of The Layermentioning

confidence: 99%

Anisotropic modeling of layered rocks incorporating planes of weakness and volumetric stress

Tan

Zhou

et al. 2019

Energy Science & Engineering

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“…[32][33][34] The mutual attraction between molecules inside the materials (ie, the cohesion) causes the molecules to coalesce into a whole. [32][33][34] The mutual attraction between molecules inside the materials (ie, the cohesion) causes the molecules to coalesce into a whole.…”

Section: Revised Mohr-coulomb Modelmentioning

confidence: 99%

Experimental study of shear failure and crack propagation in water‐bearing coal samples

Tang

Yao

et al. 2019

Energy Science & Engineering

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The design of dam bodies for underground reservoirs must account for how water affects shear failure and the evolution of fractures in coal pillars. In this work, we detect acoustic emissions in raw coal samples with different water content (0%, 5.35%, 17.88%, and 20.40%) and under uniaxial compression shear and use computed tomography to analyze the failed samples. The results show that the shear strength, shear displacement, cohesion, and internal friction angle all decrease with increasing water content, which is described by the revised Mohr‐Coulomb model for the case of water intrusion. The acoustic emission counts correlate strongly with the change in stress, and the cumulative acoustic emission counts are combined with shear stiffness to separate the fracture evolution process into five stages: crack closure, elastic deformation, stable crack propagation, unstable crack propagation, and failure. The ratios of the crack closure, initiation, and damage stress to the corresponding peak shear stress are essentially unaffected by the water content. Most cracks are tensile cracks, and an increase in the water content promotes the development of parallel fractures. These results are helpful for determining the size of coal pillars in underground reservoirs and for solving other underground engineering problems, such as support for water‐rich coal roadways.

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“…Gas shale has received increasing attention recently, and its mechanical behavior (compressive, shear, tensile and fracture behavior) plays an important role in shale gas extraction [5][6][7][8]. The mechanical behavior is concerned with wellbore collapse and leakage in the process of drilling, and hydraulic fracturing during the process of exploitation [9][10][11][12]. To present the anisotropic degree of "BtS" for different rocks, Figure 1 compares the maximum and minimum "BtS" for various anisotropic rocks.…”

Section: Introductionmentioning

confidence: 99%

Brazilian Tensile Strength of Anisotropic Rocks: Review and New Insights

Peng

Zhu

et al. 2018

Energies

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Strength anisotropy is one of the most distinct features of anisotropic rocks, and it also normally reveals strong anisotropy in Brazilian test Strength ("BtS"). Theoretical research on the "BtS" of anisotropic rocks is seldom performed, and in particular some significant factors, such as the anisotropic tensile strength of anisotropic rocks, the initial Brazilian disc fracture points, and the stress distribution on the Brazilian disc, are often ignored. The aim of the present paper is to review the state of the art in the experimental studies on the "BtS" of anisotropic rocks since the pioneering work was introduced in 1964, and to propose a novel theoretical method to underpin the failure mechanisms and predict the "BtS" of anisotropic rocks under Brazilian test conditions. The experimental data of Longmaxi Shale-I and Jixi Coal were utilized to verify the proposed method. The results show the predicted "BtS" results show strong agreement with experimental data, the maximum error is only~6.55% for Longmaxi Shale-I and~7.50% for Jixi Coal, and the simulated failure patterns of the Longmaxi Shale-I are also consistent with the test results. For the Longmaxi Shale-I, the Brazilian disc experiences tensile failure of the intact rock when 0 • ≤ β w ≤ 24 • , shear failure along the weakness planes when 24 • ≤ β w ≤ 76 • , and tensile failure along the weakness planes when 76 • ≤ β w ≤ 90 • . For the Jixi Coal, the Brazilian disc experiences tensile failure when 0 • ≤ β w ≤ 23 • or 76 • ≤ β w ≤ 90 • , shear failure along the butt cleats when 23 • ≤ β w ≤ 32 • , and shear failure along the face cleats when 32 • ≤ β w ≤ 76 • . The proposed method can not only be used to predict the "BtS" and underpin the failure mechanisms of anisotropic rocks containing a single group of weakness planes, but can also be generalized for fractured rocks containing multi-groups of weakness planes.

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Experimental and theoretical study of the anisotropic properties of shale

Cited by 182 publications

References 47 publications

Anisotropic modeling of layered rocks incorporating planes of weakness and volumetric stress

Anisotropic modeling of layered rocks incorporating planes of weakness and volumetric stress

Experimental study of shear failure and crack propagation in water‐bearing coal samples

Brazilian Tensile Strength of Anisotropic Rocks: Review and New Insights

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