Determining the dominant rock properties affecting the impact hammer performance

Researchers have consistently made endeavors to suggest more accurate performance prediction models for mechanical excavators. Apart from machine related parameters, physical and mechanical properties of rocks have an impact on excavation performance. In this research, using the data collected from Levent-Hisarüstü metro tunnel (Istanbul), an attempt was made to find the rock properties that are more closely related to performance of impact hammers. The tunnel was divided into 60 zones. For each zone, the instantaneous breaking rate (IBR) of the hammer used to excavate the tunnel was recorded. The rock quality designation (RQD), uniaxial compressive strength (UCS), Brazilian tensile strength (BTS), density (ρ), Schmidt hammer hardness (SHH), Shore Scleroscope hardness (SSH), and Cerchar abrasivity index (CAI) were realized for each zone. Next, the correlations between each possible pair of the rock properties were investigated. The results were tested for significance at 0.99 and 0.95 confidence intervals.