Tunnel boring machines (TBMs) can face a variety of common issues during underground construction that may impact progress, safety, and costs. Here are some typical problems:

　　1. Geological Condition Changes: TBMs may encounter unexpected difficulties when passing through different geological structures, such as hard rock, soft soil, fault zones, and underground water. These conditions can reduce cutting efficiency, increase cutter head wear, and cause ground settlement issues.

　　2. Cutter Head Wear: The cutter head is a critical component of the TBM. Prolonged contact with hard rock can lead to wear, necessitating regular replacement and maintenance to maintain cutting efficiency and construction quality.

　　3. Seal Failure: The TBM's sealing system is essential for preventing groundwater infiltration. If the seals wear out or get damaged, leaks can occur, increasing construction risks. Timely replacement or repair of seals is necessary.

　　4. Thrust System Malfunctions: The thrust system of a TBM provides the forward driving force. Any malfunction can halt construction and require urgent repairs, potentially delaying progress.

　　5. Bearing Failures: The main bearing and other bearings in a TBM bear enormous pressure. If they fail, the entire machine may stop working, requiring major repairs or replacements.

　　6. Electrical System Issues:  The TBM's electrical system is complex. Short circuits or control system failures can incapacitate parts or the entirety of the machine.

　　7. Soil Pressure Balance Issues:  When operating in soft soil layers, maintaining appropriate soil pressure balance is crucial to prevent ground settlement and tunnel collapse. A malfunction in the soil pressure balance system can lead to severe consequences.

　　8. Cutter Head Cooling System Failures:  The cutter head generates a lot of heat during high-speed cutting. A cooling system failure can cause the cutter head to overheat, affecting cutting efficiency and the equipment’s lifespan.

　　9. Installation Errors:  The accuracy of TBM installation is vital for subsequent construction. Any installation error can lead to tunnel alignment deviations, increasing the difficulty and cost of later corrections.

　　10. Operational Errors:  Operator errors can cause equipment damage and construction accidents. Therefore, training and management of operators are critically important.

　　To address these common issues, TBM maintenance teams must conduct regular inspections and maintenance to promptly identify and resolve problems, ensuring the TBM’s normal operation and construction progress. Additionally, special construction measures and technical approaches may be required to handle complex geological conditions.