Abstract
To evaluate the influence of water content on the hard coal dynamic behavior, the dynamic tensile properties of saturated coal Brazilian disk (BD) samples were studied using a split Hopkinson pressure bar system, and dry samples were also tested as a control group. In the range of impact speeds studied, the tensile strength of the saturated coal is lower than that of the dry specimen. A synchronized triggering high-speed camera was used to monitor the deformation and failure process of dry and saturated coal samples, allowing analysis of the failure stages and mechanism of dynamic BD test, the broken mode was classified into three types, which can be classified into unilateral tensile failure, bilateral or multilateral tensile failure, and shear failure. Finally, fragments smaller than 5 mm in diameter were statistically analyzed. There is less debris in range of 0–5.0 mm for the saturated coal sample than for the dry coal. This study provides some information about the dynamic response of the hard coal for the relevant practical engineering.
Highlights
With increased intensity of deep mining, disasters such as rock burst, coal and gas outbursts have become more frequent, seriously affecting the safety of coal production [1,2,3]
The water injection technique changes the fracture structure of the coal mass and weakens the brittleness of the coal seam
7, the dynamic tensile strength of the dry coal increased with increased loading rate
Summary
With increased intensity of deep mining, disasters such as rock burst, coal and gas outbursts have become more frequent, seriously affecting the safety of coal production [1,2,3]. The water injection technique changes the fracture structure of the coal mass and weakens the brittleness of the coal seam. Application of this approach relieves the energy stored in coal over a large range, widens the plastic deformation zone in front of the coal wall, and shifts the stress concentration zone into the deep coal mass. Shan [16] proposed a new test method to measure fracture the toughness coal samples. The effect of impact velocities on dynamic tensile strength of coal characteristics of hard coal. The effect of impact velocities on dynamic tensile strength of coal samples was analyzed. The distribution characteristics of debris after coal sample crushing were compared and analyzed
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