Evaluating the Effect of Diameter-to-Length Ratio in Point Load Index Test on Predicting Uniaxial Compressive Strength

Abstract

Accurate determination of the strength properties of rock materials is very important in engineering projects. The most important parameter used to express the strength of rocks is the uniaxial compressive strength (UCS). However, in some cases it can be quite difficult to determine the UCS. For example, when it is difficult to obtain rock specimens of the required size for UCS testing, indirect methods such as point load strength and ultrasonic wave velocity are used to estimate UCS. If the UCS is determined incorrectly, this can lead to irreversible design errors, project delays and financial losses. PLI testing is performed on specimens of different shapes as well as on specimens of different sizes. This study investigates the ability of the values obtained as a result of PLI tests on specimens prepared with different diameter/length (D/L) ratios to predict UCS. For this purpose, PLI experiments were performed on seven different carbonate rocks prepared at different D/L ratios. The relationships between the obtained values and the UCS values of the rocks were analyzed. High correlations were obtained between PLI and UCS values and it was observed that D/L ratio has no significant effect on UCS estimation.