The effect of cutting disc screening diagrams on tunnel boring machine performance

The mechanized tunneling industry has improved from past to present by means of many methods such as different ground conditions, manpower or machine power. Thanks to the developments in industrialization today, fast and economical tunnel boring machines (TBM) have been developed that prioritize human safety. The frequency of preference of TBM's in projects is increasing day by day due to the ease of use, the advantage of working on difficult soil, the benefits it provides in work safety, working time and working costs. The primary product in the design of tunnel boring machines is the cutter head, which varies according to the ground conditions. The cutter discs allows the cutter head to penetrate the ground. During the fracturing of the ground, tumbling, normal and axial forces occur on the cutting discs. The forces generated during soil fracturing create torque and thrust forces that enable the cutter head to penetrate the ground. In this study, information is given about the tunnel boring machine (TBM) classes, main parts of the machine, cutter head types, cutter types and the importance of cutter head design suitable for different geologies. Irremediable damage to the cutters that did not operate at appropriate loads during excavations has been investigated in the study. According to the determined soil characteristics, a cutter head scanning diagram with a excavation diameter of 3025 mm has been created. According to the boundary conditions, the calculations of the bearings in the cutting discs were made and the operating time was examined according to the scanning diagram. As a result of the full-size cutting tests carried out in the study, it has been seen that the surface cutter discs can operate with higher normal force than the angle cutter discs. It was concluded that the chisel distances of the angled cutter discs in the cutter head scan diagram should be lower than the surface cutter discs. Key Words: Tunnel Boring Machines (TBM) , Cutter Head, Cutting Disc, Cutter Head Scanning Diagram, Thrust Force and Torque