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| EXPERIMENTAL STUDY ON MECHANICAL AND ANISOTROPIC PROPERTIES OF BLACK SHALE |
| CHEN Tianyu1,FENG Xiating1,2,ZHANG Xiwei1,CAO Weidong1,FU Changjian1 |
(1. Key Laboratory of Ministry of Education on Safe Mining of Deep Metal Mines,Northeastern University,Shenyang,Liaoning 110819,China;2. State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,
Chinese Academy of Sciences,Wuhan,Hubei 430071,China) |
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Abstract Geochemical parameters of lower Cambrian black shale at Niutitang were measured in order to study the mechanical and anisotropic properties of black shale. The brittle mineral content of the lower Cambrian black shale at Niutitang was found to be as high as 79.01%. The scanning electron microscopy was used to obtain the microscopic structure of the black shale. The layered sedimentary characteristics and the lamellar structure of alternating plates were observed to exist in the black shale. Series of triaxial compression experiments on the black shale samples with different angles of bedding were carried out with the testing system ROCKMAN207,which was developed by Northeastern University and Chaoyang testing instrument company at Changchun. The whole stress-strain curves and failure modes were obtained. The effects of confining pressure and the angle of bedding on the mechanical behavior and failure modes of shale were analyzed. The stress-strain curves of the black shale exhibited no obvious stage of compaction of fissures and pores,and were largely straight lines ahead of the peak point. The failure modes of the black shale were related to the confining pressure and the angle of bedding. Under the condition of low confining pressure,complex networks of fractures were formed easily after the failure of the rock sample. When the axial loading direction was parallel to the shale?s bedding,the complex fracture networks were formed more easily. The wave velocity of the black shale samples decreases with the increase of the bedding angle. The anisotropic strength curve of the shale is U-shaped. The anisotropic coefficient of the black shale decreases with the increase of confining pressure.
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Received: 28 April 2014
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