Predicting the Uniaxial Compressive Strength and Static Young’s Modulus of Intact Sedimentary Rocks Using the Ultrasonic Test

The uniaxial compressive strength and static Young’s modulus $\left(E_s\right)$ of intact rocks are the most important geotechnical parameters for stability analysis of surface and underground structures. These parameters are obtained by the uniaxial compressive test. Although this test is simple, the preparation of the samples, especially of soft rocks, is a hard and time consuming task. By using a nondestructive method such as the ultrasonic test, one can indirectly predict the mentioned parameters. The uniaxial compressive and the ultrasonic tests were carried out on 64 samples of sedimentary rocks and, after regression analysis of the test results; best fit equations for predicting the uniaxial compressive strength and static Young’s modulus of these samples are proposed. Thus, in comparison with other proposed equations, these equations have larger value of accuracy and correlation coefficient $\left(R^2\right)$ . The equations are practical, simple, and accurate enough to apply and can be used in practice for the prediction purposes with acceptable accuracy.