The tunnel boring machine is a special mechanical equipment used for underground projects such as tunnel construction and mining. According to the different shapes of the tunnel boring machine head, the tunnel boring machine is mainly divided into arm-type tunnel boring machine and cutter-type tunnel boring machine. These two types of tunnel boring machines have their own characteristics in structure, function and applicable scenarios.

　　1. Arm-type tunnel boring machine

　　The head shape of the arm-type tunnel boring machine is like a long arm, usually composed of a multi-degree-of-freedom mechanical arm and a cutting tool. This design gives the arm-type tunnel boring machine the following characteristics:

　　High flexibility: The arm-type tunnel boring machine can adapt to different working surfaces by adjusting the angle and position of the mechanical arm, so it performs well in tunneling operations with complex and irregular shapes.

　　High operating accuracy: The multi-degree-of-freedom design of the mechanical arm enables it to accurately control the motion trajectory of the cutting tool, which is suitable for engineering projects that require precise excavation.

　　Wide scope of application: The arm-type tunnel boring machine is suitable for tunnel excavation in underground mines such as coal mines and metal mines, as well as tunnel projects with complex geological conditions.

　　However, the structure of the boom-type TBM is relatively complex, the maintenance cost is high, and the efficiency is relatively low when excavating large-section tunnels.

　　2. Cutterhead TBM

　　The head of the cutterhead TBM is shaped like a disc, on which a large number of cutting tools are installed. Its main features are as follows:

　　High excavation efficiency: The cutterhead TBM continuously cuts rocks or soil layers by rotating the cutterhead, which is suitable for long-distance and large-section tunnel excavation projects.

　　Good stability: The cutterhead TBM has high stability during the excavation process and can cope with high-strength and high-hardness geological conditions.

　　High degree of automation: Modern cutterhead TBMs are equipped with advanced control systems and sensors, which can realize automated operation and improve the safety and efficiency of excavation.

　　However, the cutterhead TBM has poor flexibility when facing irregular terrain and complex geological conditions, and the initial investment is high. It is mainly used in tunnels and underground projects with relatively stable geological conditions.

　　Boom-type TBMs and cutterhead TBMs each have unique advantages and applicable scenarios. With its flexibility and high operating precision, the boom-type TBM is suitable for underground projects with complex shapes and variable geological conditions; the cutterhead TBM is widely used in large-section tunnels and engineering projects with relatively stable geological conditions due to its high efficiency, stability and high degree of automation.

　　Diversity and selection of TBMs

　　With the continuous growth of demand for underground engineering and mining, the technology of TBMs is also constantly improving. To choose the appropriate type of TBM, it is necessary to comprehensively consider the specific needs of the project, geological conditions and economic costs. By rationally selecting and using TBMs, it is possible to effectively improve the efficiency of tunneling, reduce construction risks and promote the development of underground engineering.