A general evaluation of the performance of roadheaders used in coal mines

Roadheaders have been widely used in mining and civil engineering projects for the excavation of roadway or tunnel in soft and medium strength rocks. The correct estimation of roadheader performance is important especially for determining project duration and cost estimation. Since the available models for the performance prediction of roadheaders do not include rock mass properties, the development of the performance prediction models including rock mass properties can be very useful. The main objective of this study is to investigate whether generalized performance prediction models including cutter head power and a new rock mass cuttability classification (RMCC) index can be developed for roadheaders used in coal mines. The suggested RMCC system includes intact rock strength, rock mass properties such as discontinuity properties, rock abrasivity, and ground water parameters. The performance measurements of roadheaders were carried out in coal mines in Türkiye. The measurements for RMCC system were performed in conjunction with performance measurements, and block samples were collected for the laboratory tests. The Net Cutting Rate (NCR) and the Machine Utilization Time (MUT) values were calculated from the performance measurements. The RMCC index values were calculated from the field measurements and the laboratory tests. That there were the high correlations between NCR and RMCC index for similar conditions indicated the validity of the RMCC system. It was observed that MUT values varied between 20% and 30%. For the prediction of Net Cutting Rates of roadheaders, multiple regression models including cutter head power, RMCC value, and other parameters were developed for axial and transverse type machines. The validity of the derived models was checked by F- and T-tests. Concluding remark is that especially nonlinear developed models can be reliably used for the performance prediction of roadheaders used in coal mines. Keywords: Roadheaders, Net cutting rate, Rock mass cuttability classification system