Quantification of strength anisotropy of metamorphic rocks of the Hamedan province, Iran, as determined from cylindrical punch, point load and Brazilian tests

• Five anisotropic rocks were subjected to punch, point load and Brazilian tests.
• Mechanical properties of tested samples were evaluated at seven anisotropy angles.
• Results show that CPI, Is(50) and BTS are affected by anisotropy angle (β).
• Some new empirical equations relating studied indices were obtained.

In this research, different experimental techniques have been used to determine the strength of five types of anisotropic foliated rocks, selected from different parts of the Hamedan Province, west of Iran. For this purpose, after sample preparation and assessment of mineralogical and physical properties, selected samples were subjected to Cylindrical Punch, Point Load and Brazilian tests and their strengths were evaluated with respect to different angles, beta (i.e. β = 0°, 15°, 30°, 45°, 60°, 75° and 90°), between anisotropy planes and the major loading directions. Data analyses show that the types and amounts of minerals have an influence on the physical and mechanical properties of the tested anisotropic rocks. Porosity and water absorption also have a dominant control on the mechanical indices such as cylindrical punch index (CPI), point load index (Is(50)) and Brazilian tensile strength (BTS). On the basis of the test result, two empirical equations (Eqs. (3) and (5)) are proposed for calculating CPI and Is(50). Other empirical equations relating studied indices are also presented.