The double shield TBM mainly consists of a front shield equipped with a cutter head and a cutter head drive, a gripper shield equipped with a support device(gripper shoes), a telescopic shield connecting the front and gripper shields and a tail shield where installs the segments. The double shield TBM can be used for hard rock and soft rock. It is commonly used in mixed formation construction, and its geological adaptability is very wide.

It has two tunnelling modes, double-shield mode and single-shield mode. When excavating in a stratum with better surrounding rock stability, the gripper shoes located on the gripper shield are tightly supported on the wall of the rock, providing reaction force for the cutter head and the front shield, and under the action of the main propulsion cylinders, the TBM moves forward. The double-shield excavation mode is suitable for the construction of hard rock formations with good stability. In this mode, the excavation and installation of segments are carried out at the same time, and the construction productivity is very high. The single-shield excavation mode is suitable for unstable and unfavorable geological areas. When excavating in weak surrounding rock formations, the rock cannot provide sufficient supporting reaction force to the gripper shoes, so the gripper shoes and the main propulsion system are no longer used, the telescopic shield is in the retracted position, and the double shield TBM is equivalent to a single shield TBM. The thrust of the cutter head is provided by the auxiliary propulsion cylinder pushing against the segment, and the TBM excavation and segment installation cannot be carried out in parallel.