The relationships between Brazilian tensile strength and ultrasonic pulse velocity in rock material

Recent studies emphasize that the tensile strength of rock material is just as important a parameter as compressive strength although rock mechanics research and engineering designs often focus on the uniaxial compressive strength of rocks, in determining tensile strength, which can be identified through direct and indirect methods, the use of indirect methods is preferred over direct methods due to the difficulties associated with their application. The most commonly used indirect method is the Brazilian test. However, this testing method also involves certain challenges due to the requirement for samples with specific properties and dimensions. The most practical approach to overcoming these challenges is to estimate the tensile strength of the rock using non-destructive testing methods. The aim of this study is to predict the Brazilian tensile strength of rock material using the propagation velocities of P-waves obtained from a non-destructive test type, the sonic velocity test. For this purpose, a total of 90 core samples from 8 different rock groups were prepared, and Brazilian and sonic velocity tests were conducted on these samples. Experimental data were evaluated using simple regression models to determine the predictability of Brazilian tensile strength based on P-wave velocity in rock material. The results from the regression models indicate a very strong-strong correlation between the Brazilian tensile strength and P-wave velocity parameters within each rock group. However, the regression model that evaluates the data from all rock groups together shows a weak correlation between the Brazilian tensile strength and P-wave velocity parameters. The primary reason for this is that both tensile strength and P-wave propagation velocity are significantly influenced by lithological properties.