First, the semi-lining structure: In the hard rock layer, the sidewalls do not collapse danger, only the top of the rock may have a partial slip, you can only set the top lining, do not do the side wall.

Second, thick arch thin wall lining structure: In the middle hard rock layer, the power of the dome can be passed to the rock mass through most of the arch foot, make full use of the strength of the rock, so that the force on the side wall is greatly reduced, This reduces the thickness of the side wall.

Third, straight wall arch lining structure: integrity and stress performance, waterproof and moisture-proof difficulties, large amount of excavation, difficult to repair.

4. Curved wall lining structure: In poor rock formations, loose rock bodies are easy to collapse, and the lining structure is generally composed of arches, curved side walls and bottom arches. Good mechanical performance and high construction requirements.
5. Composite lining structure: It is composed of initial support and secondary support, and has high waterproof requirements.

Sixth, multi-arch tunnel structure: suitable for small and medium-sized tunnels.