The influence of bedding plane orientation on rock breakages in biaxial states

Bedding planes are weak structural planes in rock masses, significantly affecting rock properties. In the present article, the indentation and morphology scanning tests have been conducted to investigate the influence of the bedding plane orientation on rock breakages in biaxial states. First, the indentation tests show that the increase in δ restrained the propagation of both internal and surface cracks. Then, the theoretical analysis properly validated this conclusion. In addition, the morphological scanning tests show that these restraints on crack propagation directly led to the shrinkage of grooves. It is believed that the crack propagation is responsible for the chip formation when δ is low, whereas chips frequently form by shear failure for higher δ. Furthermore, the recorded AE, reflecting the crack propagation level, also indicates that fiercer crack propagation occurred for lower δ. Simultaneously, the sharp drops of the indentation force frequently were accompanied with promoted AE. With the consumed energy and the groove volume, it can be concluded that the increase in δ restrains the crack propagation and further leads to the decrease in indentation efficiency.