Estimation of mechanical properties of sandstones using P-wave velocity and Schmidt hardness

Uniaxial compressive strength (UCS), modulus of elasticity (E) and Brazilian tensile strength (BTS) are important properties of intact rock which are used widely in rock engineering. The determination of these parameters in laboratory is difficult, expensive and time consuming. Thus, it has been attempted that the empirical equations to estimate the mechanical properties of sandstones using P-wave velocity and Schmidt hardness as two non-destructive and easy tests were developed. For this purpose, 30 rock blocks of sandstone have been collected from several parts of Upper red formation in southwestern Qom and they were tested in the laboratory. The laboratory tests include the determination of P-wave velocity and Schmidt hardness, and mechanical properties include the uniaxial compressive strength, modulus of elasticity and Brazilian tensile strength. Empirical equations have been developed for estimating the mechanical properties from P-wave velocity and Schmidt hardness using regression analysis. To check the validity of the empirical equations, t and F test were performed, which confirmed the validity of the proposed empirical equations. Moreover, the results show that P-wave velocity appears to be more reliable than the Schmidt hardness for estimating the mechanical properties.