Journal
INTERNATIONAL JOURNAL OF ROCK MECHANICS AND MINING SCIENCES
Volume 77, Issue -, Pages 60-67Publisher
PERGAMON-ELSEVIER SCIENCE LTD
DOI: 10.1016/j.ijrmms.2015.03.033
Keywords
Direct shear test; Constant normal load; Coal-rock interface strength; Acoustic emission; Interface surface roughness
Funding
- National Natural Science Foundation of China [51174195]
- Open Projects of State Key Laboratory of Coal Resources and Safe Mining (China University of Mining and Technology) [11KF01]
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Surface boreholes were drilled in Southern West Virginia to obtain the specimens containing natural coal-rock interface. The shear behavior of the natural coal-rock interface was studied by performing direct shear tests under constant normal load conditions. The test results indicate that: (1) The average cohesion and friction angle of the coal-rock interfaces are 0.786 MPa and 29.7 degrees, respectively; (2) the normal stiffness of the coal-rock interface ranges from 0.57 to 444 MPa/mm, while the shear stiffness varies from 1.14 to 3.47 MPa/mm. Additionally, analysis on the shear behavior of the coal-rock interface and the corresponding AE signals during shearing indicates that AE can be used to evaluate the shear behavior of the coal-rock interface. Furthermore, it has been found that when normal loads are smaller than 3 kN (equivalent normal stress < 1.5 MPa), the shear behavior of coal-rock interface strongly depends on the surface roughness of coal-rock interface; as the normal load is increased to or larger than 4 kN (equivalent normal stress > 2.0 MPa), however, the shear behavior of coal-rock interface are more influenced by the strength differences between the two halves rather than the surface roughness of the coal-rock interface. (C) 2015 Elsevier Ltd. All rights reserved.
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