Empirical equations between characteristic impedance and mechanical properties of rocks

Abstract Based on a great number of experimental data on various mechanical properties of rock in the literature, six empirical equations between the characteristic impedance (product of density and P-wave velocity) and mechanical properties of rock are proposed. These properties include uniaxial compressive strength, tensile strength, shear strength, mode I fracture toughness, Young’s modulus, and Poisson’s ratio. These empirical equations show that the values of the aforementioned properties increase with increase in characteristic impedance. It also implies that the characteristic impedance of rock may be considered as an index to represent the main properties of rock. In this sense, it is possible to consider using characteristic impedance to classify rock masses for studies in the future.