Building a safe underground corridor, especially for a DIY project, is extremely dangerous and not recommended. Unstable ground conditions, unexpected utilities, and lack of proper ventilation and support structures can all lead to collapse and serious injury or death. However, if you're interested in the professional approach, here's what you should know:

Safety First:

Professional tunnel construction involves a team of qualified engineers, geologists, and construction workers. They prioritize safety through:

• Geotechnical Surveys: Analyzing the soil composition and stability is crucial to determine the best tunneling method and potential risks.
• Shoring and Support Systems: Temporary structures like steel beams, shotcrete (sprayed concrete), or rock bolts hold back the surrounding earth to prevent cave-ins.
• Ventilation Systems: Tunnels require proper ventilation to remove dust and ensure a safe oxygen level for workers.
• Emergency Plans and Monitoring: Protocols are in place to address emergencies and continuously monitor the tunnel's stability.

Technology Choice - Concrete Reigns Supreme:

For permanent underground structures, concrete is the preferred material due to its:

• Strength and Durability: Concrete can withstand significant loads from the surrounding earth.
• Versatility: It can be cast in-situ (on-site) or prefabricated into segments for faster assembly.
• Water Resistance: Concrete helps prevent water infiltration, a major concern underground.

Bricks, while strong, are not ideal for extensive underground structures because:

• Limited Load Bearing Capacity: They may not be strong enough for deep tunnels or wide corridors, particularly in unstable soil conditions.
• Water Permeability: Brick walls require additional waterproofing measures to prevent leaks.

Construction Methods:

There are various tunneling methods depending on the size, depth, and ground conditions. Here are two common approaches:

• Cut-and-Cover: A trench is excavated from the surface, the corridor is built within the trench, and then the surface is restored. This method is suitable for shallow corridors but might disrupt existing structures.
• Tunneling Machines (TBMs): Large rotating machines with cutting heads are used to excavate the tunnel while simultaneously installing prefabricated concrete segments or shotcrete lining. TBMs are efficient for deeper tunnels but require significant upfront investment.

The Takeaway:

Professional tunnel construction is a complex undertaking that prioritizes safety and utilizes specialized techniques and materials. Attempting a DIY underground corridor is extremely risky. If you require an underground passage, consulting a professional engineer experienced in safe tunnel construction is the only recommended approach.