Use of rock microscale properties for introducing a cuttability index in rock cutting with a chisel pick

Accurate estimation of rock cuttability is crucial for selecting and design of mechanical excavators in mining and civil engineering practices. This study is to introduce the intact rock cuttability index (IRCI) using three simple and easily accessed intact rock microscale parameters. Assuming that an intact rock consists of mineral grains (materials), cement or matrix and pores, three parameters of rock texture coefficient (TC), Cerchar abrasivity index (CAI), and porosity were selected to be included in IRCI equation. Small-scale rock cutting tests with a simple chisel pick were conducted on very low to medium strength rock specimens to calculate the specific energy (SE) as an indicator of rock cuttability. Accordingly, the correlations between rock physical and mechanical properties, IRCI, and SE were investigated. The analysis results showed that the rock strength parameters (i.e., UCS and BTS) are not well described by texture coefficient, while they were well correlated with the cuttability index developed based on rock microscale properties. The results also showed that there is a strong correlation between the intact rock cuttability index and specific energy. These findings, although promising, are preliminary. Hence, further studies are underway with additional data sets to examine the validity and extend the model to actual size cutting tools.