ABSTRACT
The rock is cored in the laboratory by using a 50 mm diameter drill bit. The direction of coring is parallel to the layers. Disc-shaped samples have a diameter of 50 mm and a thickness of approximately 18 mm. It should be noted that the thickness-to-diameter ratio of about 0.36 used in this research does not match with the ISRM recommendations for Brazilian test (i.e. around 0.5). However, for research purposes, it is better to use smaller thickness-to-diameter ratio specimens in order to make the stress distribution along the thickness of the disc more similar (Lavrov et al. 2002).
