Integrated lining is an important form of support in tunnel construction. Its main function is to provide a sturdy and stable inner wall for the tunnel to resist external soil pressure, groundwater pressure, and possible seismic forces. At the same time, it can also improve the environmental conditions inside the tunnel, such as reducing water seepage and improving ventilation efficiency.

　　Structure and Characteristics

　　Integral lining is usually made of reinforced concrete or prestressed concrete, which has good integrity and durability. Its structural characteristics are as follows:

　　1. Integrity: The integral lining is continuously poured or assembled to form a seamless whole, which can effectively disperse loads and improve the safety and stability of the structure.

　　2. High stiffness: Compared to other forms of lining, integral lining has higher stiffness, which can better resist external loads and reduce deformation.

　　3. Good waterproof performance: By setting a waterproof layer inside the lining, the integral lining can effectively prevent groundwater infiltration and protect the internal structure of the tunnel from erosion.

　　4. Strong durability: Using high-quality concrete materials and construction techniques, the integral lining has a longer service life and reduces the frequency of maintenance and repair.

　　Construction technology

　　The construction of integral lining usually includes the following steps:

　　1. Excavation and initial support: Firstly, the tunnel outline is formed through excavation, and then initial support is carried out to ensure construction safety.

　　2. Waterproof layer construction: Before lining, lay a waterproof layer to prevent groundwater infiltration.

　　3. Template installation: Install templates according to design requirements to ensure the shape and size of the lining.

　　4. Concrete pouring: Use a concrete pump or pouring equipment to evenly pour concrete into the formwork to form a lining.

　　5. Maintenance and formwork removal: After the concrete is poured, maintenance is carried out, and the formwork is removed after reaching a certain strength.

　　Application scenarios

　　Integrated lining is widely used in subway tunnels, highway tunnels, water conservancy tunnels, mining tunnels and other engineering projects, especially in situations with complex geological conditions, abundant groundwater or high requirements for tunnel stability. The advantages of integrated lining are more obvious.