Estimation of uniaxial compressive strength of rock material using block punch index and ultrasonic velocity test

The strength of rock materials is a fundamental parameter for the safe and economical design of engineering projects. This strength is influenced by properties such as the physical structure, mineral composition, crack condition, and porosity of rocks, with unconfined compressive strength (UCS) being one of the most commonly used strength indicators in engineering applications. However, the application of the UCS test can be limiting due to the need for high-quality samples, complex preparation processes, and expensive equipment. This has increased the interest in indirect methods for determining UCS in field conditions where direct measurement is not feasible. In this study, the predictability of UCS using indirect methods such as Block Punch Index (BPI) and ultrasonic velocity measurements (Vp) has been investigated. The BPI test evaluates the shear strength of rocks, while ultrasonic tests provide non-destructive insights into the elastic properties of the rock's internal structure. In the study, UCS and ultrasonic velocity tests were conducted on a total of 73 core samples from four different lithological rock groups, and tests were also performed on 73 BPI-prepared samples. The obtained data were evaluated using regression analyses. The results demonstrated a strong relationship between both parameters and UCS prediction, with a particularly high accuracy in the relationship between BPIc and UCS. Furthermore, it was observed that lithological differences and porosity influenced the relationship between UCS and Vp. The equations derived from this study offer reliable and highly accurate alternatives for predicting the strength of rock materials.