Open Cut Method is a common method for tunnel or underground structure construction, mainly used for the construction of shallow buried tunnels and underground buildings. This method excavates the ground first, completes the construction of the tunnel or underground structure, and then backfills and restores the surface. The following are some key steps and characteristics of the open cut method:

　　I、Advantages and Disadvantages of Open Cut Method

　　1. Advantages:

　　1> Simple construction: The open cut method is relatively simple to operate and is suitable for shallow buried tunnels and underground structures.

　　2> Low cost: Compared with other tunnel construction methods (such as shield method or mining method), the construction cost of the open cut method is usually lower.

　　3> Fast construction progress: Since the surface is completely exposed, the transportation and installation of construction equipment and materials are more convenient, and the construction speed is faster.

　　2. Disadvantages:

　　1> Large impact on the environment: Surface excavation will have a greater impact on the surrounding environment, especially in densely populated urban areas, which may cause traffic disruptions, noise and dust pollution.

　　2> Limited scope of application: The open-cut method is only applicable to shallow buried projects, not deep buried tunnels and underground structures.

　　3> Risk of surface subsidence: If the construction process is not properly controlled, it may cause surface subsidence and affect the safety of surrounding buildings.

　　II、Construction steps of the open-cut method

　　1. Surface excavation: First, fence the construction area and dig up the surface soil until the design elevation is reached. Slope stability needs to be considered during excavation, and support structures (such as retaining walls or soil nail walls) may be used to prevent collapse.

　　2. Support structure construction: After excavating to the designed depth, temporary or permanent support structures are installed according to geological conditions and construction requirements to ensure the stability of the excavated space.

　　3. Structural construction: Construction of tunnels or underground buildings in the excavated space, usually including the casting or installation of the bottom plate, side walls and top plate.

　　4. Waterproofing and drainage: In order to prevent groundwater from infiltrating, waterproofing measures will be taken during the construction process, such as laying a waterproof layer or drainage system to ensure the dryness and stability of the structure.

　　5. Backfilling and surface restoration: After the structure is completed, backfilling operations are carried out, the earthwork is compacted layer by layer, and finally the surface is restored to its original or designed state, such as restoring roads, green spaces or other surface facilities.

　　Open-cut method is widely used in shallow buried projects such as subway stations, underground passages, and underground pipe galleries. With the advancement of urbanization, open-cut method plays an important role in the development of urban underground space.