Tunnels are one of the masterpieces in the history of human engineering, connecting geographical barriers and carrying essential functions such as transportation, water supply, and energy.

The construction process of a tunnel requires precise planning, a strong engineering team, and advanced technology.

Let's take a look at how tunnels are built.

Planning and Preparation

1. Site Selection and Survey

The first step in tunnel construction is site selection and survey. Engineers must carefully study factors such as topography, geology, and groundwater levels to choose the best tunnel route. Geological surveying is particularly crucial, as different geological conditions require different tunnel designs and construction methods.

2. Design

Once the site is determined, the engineering team proceeds with detailed design work.

This includes determining the length, width, and height of the tunnel, as well as the placement and layout of facilities such as ventilation systems, lighting, and drainage. Tunnel design must take into account the intended use of the tunnel in the future, whether it's for road, railway, or water supply purposes.

3. Permit Acquisition

Tunnel construction involves various aspects such as land use and environmental impact, so obtaining permits and approvals from relevant government departments is necessary. These permits typically undergo rigorous review to ensure that tunnel construction complies with laws, regulations, and environmental standards.

4. Preparation Work

Before actual construction begins, a series of preparation work is necessary.

This includes clearing the construction site, setting up temporary facilities, and transporting and storing building materials. The large equipment and materials required for tunnel construction also need to be prepared in advance to ensure smooth progress.

Tunnel Construction

1. Excavation

Excavating the tunnel is one of the most challenging phases of the entire construction process. There are several methods commonly used for tunnel excavation, such as traditional blasting methods, Tunnel Boring Machine (TBM) methods, and diamond drilling methods, among others. The choice of method depends on geological conditions and tunnel design.

- Traditional Blasting Method: Often used in situations where the rock is hard and geological conditions are complex. Workers use drilling, loading explosives, and blasting to gradually excavate the tunnel.

- Tunnel Boring Machine (TBM) Method: This is a modern method that uses large tunnel boring machines, which can accurately excavate tunnels in a relatively short time. TBMs not only improve construction efficiency but also reduce environmental impact.

2. Support

After tunnel excavation, support work is necessary to ensure the structural stability and safety of the tunnel. This typically includes installing steel frames, grouting, and anchoring methods to prevent rock collapse or ground deformation. The choice of support also depends on geological conditions and tunnel design.

3. Installation of Facilities

A tunnel not only serves as a passage but also requires facilities to ensure convenience and safety.

This includes ventilation systems, lighting, emergency exits, drainage systems, and more. During the tunnel construction process, these facilities need to be installed and connected step by step to ensure the tunnel's functionality.

Completion and Inspection

1. Completion

After all tunnel works are finished, a comprehensive inspection and testing are conducted. The engineering team inspects the tunnel's structure, facilities, traffic conditions, etc., to ensure that the tunnel meets the design requirements.

2. Trial Run

Before the official opening, the tunnel usually undergoes a period of trial operation.

This includes testing the passage of vehicles or trains, testing the normal operation of facilities, and more. The purpose of the trial run is to identify potential issues and make adjustments to ensure the safety and smooth operation of the tunnel.

3. Final Acceptance

Finally, the completion of the tunnel requires acceptance by government authorities.

Relevant government departments will inspect the tunnel for safety, functionality, environmental protection, etc., to ensure compliance with laws, regulations, and standards. Only after acceptance can the tunnel be officially opened for public use.

Conclusion

The construction of a tunnel is a complex and precise engineering feat, involving knowledge and technology from multiple fields such as civil engineering, geology, and machinery.

Through a series of steps including planning, construction, and inspection, humans create these feats of connecting mountains and traversing strata. Tunnels are not only convenient transportation passages but also symbols of human wisdom and courage.