Conical cutters or chisel cutters are widely used in large-section drill rigs. This section is intended to show the validity of the cutter force predictor equations given in Table 4.4 in Chapter 4. It will also show the performance prediction and design of large-section drilling drums as shown in Figures 13.3 through 13.5. The equations given below were developed by Bilgin et al. (2006) based on cutting of 24 different rock samples in the laboratory with conical cutters. The predictor Equations 13.1 through 13.3 for normal force FN and cutting force FC are given below. In these equations, FC and FN values are in kgf, depth of cut d in cm, and σc in kgf/cm2. The rotary drill rig, Bauer BG 36 shown in Figure 13.1, is used in one construction site in Istanbul with three different drilling drums (Figures 13.3 through 13.5) related to the strength of geologic formation consisting of Fresh Diorite, Weathered Diorite, and Flysch or Greywacke, each having compressive strength values
of 124, 73.5, and 40.7 MPa, respectively. The characteristics of the drill rig are given in Table 13.2. Drilling depth, drilling time, peak torque, and thrust values of the drill rig were measured using a data acquisition system and the results are plotted in Figure 13.6. The aim of the numerical example is to show how thrust and torque values of a large-diameter drill rig may be calculated using the predictor equations given below.