A comparative assessment of indirect methods for estimating the uniaxial compressive and tensile strength of rocks

The uniaxial compressive and tensile strength of rocks are crucial parameters in the design stage of geotechnical structures. However, direct determination of these parameters is expensive, troublesome, time consuming, and sometimes requires high-quality core samples for tests. Therefore, this study aimed to determine the applicability of the point load strength index and Schmidt hammer hardness values to estimate the uniaxial compressive strength and tensile strength of rocks based on the regression analyses. Further, multiple regression analysis was used on datasets obtained from tested rocks. For these purposes, representative samples of volcanic, sedimentary, and metamorphic rocks were collected from 37 different points along a tunnel alignment in Northeast Turkey where hundreds of underground projects are being constructed. Results from the regression analyses showed the existence of satisfactory correlations. The results were also compared and discussed with the results obtained by other researchers conducted on different types of rocks.