The Effect of Rock Sample Dimension on the P-Wave Velocity

P-wave velocity is one of the non-destructive geophysical methods directly or indirectly used by engineering working by various filed. Thus the accuracy of the recorded P-wave velocity affects these parameters. In this survey whether the sample dimensions measured in laboratory have effect on P-wave velocity or not was investigated. Nine different rock groups were used in this study. Six different diameter core samples were prepared from each of the groups. Ultrasonic tests were carried out on the core samples having different diameter to investigate how the sound velocity varies with sample dimension. The test results were statistically analyzed using the method of least squares regression, exponential, and polynomial relationship with high correlation coefficient were found between the sample diameters and P-wave velocities. In four sample groups a decrease in ultrasonic velocity depending on an increase in diameter was observed. In five other sample groups in the samples up to 78.68 mm diameter, a decrease in P-wave velocity value was observed but a significant increase in the P-wave velocity was observed for the biggest diameter samples. This observed decrease connected with sample dimension varies dependently on physical characteristic properties of the sample.