Anisotropy and microcrack-induced failure precursor of shales under dynamic splitting

The dynamic anisotropy and failure mechanism of shales are greatly affected by bedding surfaces. To reveal the influence beddings on anisotropic characteristics under impact, Brazilian splitting tests were conducted split Hopkinson pressure bar system. fracturing process monitored high-speed camera. Meanwhile, to understand crack initiation propagation mechanism, stress buildup, shadow transfer modelled based digital image processing rock analysis method. effect dip angle spacing initiation, coalescence was analyzed. Simultaneously, spatial distribution energy magnitude crack-induced acoustic emissions captured numerically. results show that shale discs continue produce parallel cracks cambered induced high stresses at tips initial cracks; tensile strength changes in U-shaped trend with increasing; cracking percentage surfaces decreases, matrix increases increasing. In addition, acceleration growth rapid AE can be regarded as effective precursors failure.