During tunneling operations in hard rock and highly abrasive geological formations, the cutters on the cutterhead inevitably experience wear. The construction of cross-sea and deep-buried tunnels-characterized by high water pressure-imposes particularly severe wear on the cutterheads of Shield Tunneling Machines (TBMs). Timely wear detection and systematic repair are crucial for ensuring the rapid, safe, and smooth progress of TBM construction.
Research indicates that cutter wear follows specific patterns. For instance, in monzogranite formations, the cumulative wear on face cutters increases in an approximately linear fashion as their radial mounting distance from the center of the cutterhead increases; among edge cutters, those situated in the transition zone exhibit the highest cumulative wear, with wear levels gradually diminishing toward the outer and inner edges. Compared to the wear rate per unit of rolling distance, the wear rate per unit volume of rock excavated serves as a more accurate metric for quantifying the severity and speed of cutter wear.
To monitor cutter conditions in real time, online detection systems can be employed. For example, systems based on laser detection technology-utilizing retractable laser units and sensors mounted directly onto the cutterhead-can acquire cutter wear data during the brief intervals when the TBM is advancing (jacking) forward. This enables unmanned, high-precision real-time monitoring, thereby minimizing the safety risks associated with manual inspections and maintenance performed by personnel.
When the cutterhead sustains severe wear while tunneling through highly abrasive formations, systematic repair becomes necessary. These repair operations are critical for ensuring the continued rapid, safe, and smooth advancement of the TBM. The application of targeted, key repair technologies constitutes an essential component in maintaining the continuity of the tunneling project.
To address issues such as cutterhead damage or excessive torque-often triggered by adverse geological conditions such as densely jointed rock zones-comprehensive countermeasures must be implemented. These measures include optimizing the cutterhead's cutter configuration (e.g., increasing the use of disc cutters while discontinuing the use of ripper cutters to reduce torque); selecting highly wear-resistant cutter rings or adopting a strategy of more frequent cutter replacement; and optimizing the structural design of the cutterhead (e.g., calculating the optimal scraper angle to facilitate bidirectional muck removal during both forward and reverse rotation, thereby counteracting rotational forces). Furthermore, it is essential to promptly clear accumulated muck and sediment from the cutterhead to prevent the formation of "mud cakes." Where necessary, structural modifications to the equipment itself may be undertaken to enhance its adaptability to specific geological environments.
