Estimation of Specific Energy and Evaluation of Roadheader Performance Using Rock Properties and Bond Work Index

Abstract

Specific energy (SE) is defined as the amount of work required to cut a unit volume of rock and is used to estimate the performance of excavation machines. Generally, the SE value is produced from full-scale or small-scale rock cutting tests. However, these tests require expensive equipment and experienced personnel, and the testing procedure is time consuming and impractical. Therefore, for estimation of SE, this study aimed to find a solution to estimate SE using rock mechanics test results and Bond work index values (BWi), which can be produced in a more practical, less time-consuming manner and with inexpensive test equipment. Small-scale rock cutting, rock mechanics and Bond work index tests were carried out on seven rock samples, which can be grouped into two different type of rocks: marble and travertine. In addition, the instantaneous cutting rates (ICR) of a selected roadheader were calculated using SE values. Rock mechanics tests performed in this study were uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), ultrasonic velocity (V-p), Schmidt rebound hardness (R-L), corrected point load index (I-s(50)) and density (rho). The simple regression method was used to estimate SE from rock properties and BWi. As a result of this simple regression, a significant and highest correlation was found between SE vs. UCS and I-s(50). A good correlation was found between SE vs. BTS, R-L and BWi values. A moderate correlation was found between SE vs. V-p and rho.