In the recent years, the continuing trends has been towards to mechanization of shaft excavation operations. Mechanization offers safer, faster, more efficient, and more environment friendly operations in mining and tunneling. Raise Boring Machine (RBM) is one of the mechanical excavation machines that commonly used in mine and tunnel projects for excavation of shafts. This study aimed to analyze the effect of intact rock properties (uniaxial compressive strength and indirect tensile strength) and RQD (rock quality designation), as well as fault zones on the performance of a RBM (daily advance rate, consumed tricone bit torque, net pushing force, instantaneous penetration rate, unit penetration, net cutting rate, consumed tricone bit power, and field specific energy) during pilot drilling of one of the ventilation shaft in the Balya lead-zinc underground mine, Turkey. The field investigation indicated that the instantaneous penetration rate, unit penetration, and net cutting rate were the highest in the fault zone compared to the other geological units. The statistical modeling studies indicated that RQD might be a predictor for estimation of field specific energy. Additional field and laboratory data is required to improve the reliability of the discussed models in this study.
Mechanization of shaft excavation in underground mining and tunneling is one of the factors that directly affect the cost reduction and increase the profitability of mining and tunneling projects. In recent years, the continuing trends has been towards to mechanization of shaft excavation. Mechanization offers safer, faster, more efficient, and more environment friendly operations in mining and tunnelling projects.
Raise Boring Machine (RBM) is an effective means of shaft construction where bottom access is available for removal of cuttings. These machines are used for different purposes such as excavation of ventilation and ore transport shafts in mines, surge in hydropower plants, penstock lines (incline/ vertical), switching lines between underground subway tunnels (horizontal), stairs tunnels (inclined), and ventilation shafts in road and railway tunnels. A RBM uses a small diameter drill rod (around 230–350 mm) to drill a pilot hole down to the required depth. Then, the pilot drill bit is removed and replaced with a large diameter reamerhead. The reamerhead is usually then pulled back up to the upper level, creating a round shaped shaft. The flexibility in different angles / gradients / inclinations and diameters is a great advantage compared to drill and blast excavation method. The back reaming is a safe, efficient and cost-effective method of boring holes through different geological formations. This method is suitable in both hard and soft rocks being usually in massive nature. Raise boring is convenient method in competent rock; however, several problems are faced in geological formations where geological discontinuities are dominant. Besides, assembly and disassembly time may be long in some cases.
