Abstract
The static mechanical properties of coal rock show anisotropism, which makes the permeability have anisotropic characteristics partly. The dynamic impact mechanical characteristics of structural anisotropic coal under low and medium strain rates were studied by using self-made vertical Split Hopkinson Bar (SHPB) equipment. The peak stress, the strain rate, dynamic elastic modulus and failure characteristics of raw coal with three coring directions were analyzed under the influence of five impact loads and structural anisotropy. The peak stress increases linearly with impact load, and the maximum strain rate and the dynamic elastic modulus increase exponentially with impact load. The coal samples display anisotropic mechanical characteristics. The values of maximum strain rate, peak stress and dynamic elastic modulus are ranked with directions by the perpendicular to bedding direction (Z direction), the parallel to bedding direction (X direction), and the oblique 45° to bedding direction (Y direction). Dynamic mechanical properties of structural anisotropic coal provide a theoretical basis for gas seepage in far-blasting field.
Highlights
Gas drainage in coal mine could effectively prevent coal and gas outburst, but the low gas drainage efficiency of low-permeability coal takes a challenge for gas drainage [1]
These results showed that the dynamic mechanical properties of structural anisotropic coal rock are obviously different, which can be defined as anisotropic characteristics
The dynamic stress-strain, dynamic elastic modulus and dynamic intensity growth factor properties of raw coal samples with three coring directions were studied by using the selfmade vertical Split Hopkinson Bar (SHPB) device under low strain rate and five kinds of impact loads
Summary
Gas drainage in coal mine could effectively prevent coal and gas outburst, but the low gas drainage efficiency of low-permeability coal takes a challenge for gas drainage [1]. The dynamic mechanical failure properties of coal body under different impact loads are of great significance for determining the parameters of deep hole blasting. The characteristics of anisotropy are important factors that lead to the long plastic deformation stage and curve fluctuation of raw coal These results showed that the dynamic mechanical properties of structural anisotropic coal rock are obviously different, which can be defined as anisotropic characteristics. In order to reveal the dynamic mechanical properties of coal body in deep hole blasting under the different distances and directions, the coal samples in three coring directions (parallel to the bedding direction, oblique 45o to bedding direction and perpendicular to the bedding direction) were tested by the self-made vertical SHPB impact device under low strain rate and. The average value 1.21 five kinds of impact loads, which ensure the integrity of coal samples and provide the theoretical basis for the permeability test
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