Abstract
Notched semi-circular bend (NSCB) samples are prepared with different
bedding angles and subjected to dynamic loading by a modified split
Hopkinson pressure bar (SHPB) system. The static fracture toughness
(SFT) of shale or coal increases linearly with the bedding angle. Under
similar loading rates, the dynamic fracture toughness (DFT) of shale
increases as the bedding angle rises. However, the DFT of coal is much
discrete. The DFT of shale or coal increases with loading rate
increasing. DFT is much higher than SFT. For shale, there is almost a
linearly positive correlation between DFT and loading rate, while for
coal, there is a logarithmic relationship. All values of coal are much
smaller than that of shale. As the loading rate increases, the effect of
bedding angle on DFT attennuates. Notably, for bedding angle of 45°, the
cracking mode of coal is more easily affected by bedding plane, than for
other angles.