Determining the relationship between shear wave velocity and physicomechanical properties of rocks

Thorough knowledge of physicomechanical properties of rocks is crucial during the primary and secondary stages of designing a rock engineering project. Laboratory examination of these properties requires high-quality rock specimens. However, preparing such high accuracy samples is a difficult, expensive, and time-consuming task, especially in weak and fractured rocks. Hence, indirect approaches seem an attractive research area for determining these properties. The main object of this study is to develop some empirical relations to determine different physical and mechanical properties of sedimentary and metamorphic rocks based on the shear wave velocity index. To do that, several schist, phyllite, and sandstone core samples were collected from the drilled boreholes in the Marivan Azad dam in western Iran. Then, the shear wave velocity and some physical and mechanical properties of rocks were measured in dry and saturated conditions. Subsequently, statistical analyses were conducted to develop shear wave velocity-based equations to determine different rock properties, including uniaxial compressive strength, modulus of elasticity, porosity, Poisson’s ratio, slake durability index, density, and water absorption. An equation with the maximum correlation coefficient was proposed as the optimum equation to determine each of the above rock properties. Finally, the results of the proposed empirical equations were compared with those of laboratory measurements. This comparison proved the proposed equations to have high accuracy for determining the physicomechanical properties of rocks and can be used in practical projects with similar geological conditions to save time and money.