Tunnels, like any enclosed space, initially contain the atmospheric oxygen present when they are created or opened. Maintaining sufficient oxygen levels, especially in long tunnels used for transport or work, is primarily achieved through various ventilation systems that draw in fresh air from outside and expel stale air. These systems are crucial for driver safety, air quality, and worker health.
However, beyond general ventilation, specific methods are sometimes employed, particularly during construction phases, to manage and boost oxygen concentration in critical areas.
Ensuring Adequate Oxygen Levels
While natural airflow provides some oxygen, tunnels often require mechanical ventilation to ensure a constant supply of fresh air and remove pollutants like exhaust fumes or dust. Different types of tunnels use different ventilation strategies:
- Road Tunnels: Often use longitudinal ventilation (blowing air along the tunnel axis) or transverse/semi-transverse ventilation (supplying air from the side walls or ceiling and extracting it).
- Railway Tunnels: Benefit from the piston effect of trains pushing air, supplemented by shafts and fans.
- Construction Tunnels: Require robust temporary ventilation to supply fresh air to the working face and remove excavation fumes and dust.
Supplementary Oxygen Systems During Construction
During the active excavation or construction of a tunnel, the air quality at the immediate work area, known as the tunnel face, can be challenging due to confined space, machinery operation, and work processes that consume oxygen. In such scenarios, a supplementary oxygen dispersal system might be utilized to ensure adequate oxygen concentration where workers are present.
The Oxygen Dispersal System at the Tunnel Face
Based on available information, a system designed to directly address oxygen levels at the workfront exists:
- Purpose: The oxygen dispersal system is designed to diffuse oxygen to the tunnel face to increase the oxygen concentration in the air around the tunnel face. This is vital for the safety and efficiency of workers operating in the most constrained part of the tunnel construction.
- Components: This specialized system is typically composed of several key parts:
- An oxygen pipeline to transport oxygen from a source.
- Valves to control the flow of oxygen.
- An oxygen-distributing apparatus at the tunnel face to release the oxygen into the surrounding air.
| Component | Function |
|---|---|
| Oxygen Pipeline | Carries oxygen supply |
| Valves | Control oxygen flow and pressure |
| Oxygen-Distributing Apparatus | Releases oxygen at the tunnel face |
Using such a system ensures that even in a confined space with potential oxygen depletion due to work activities, the air remains safe to breathe for personnel. It acts as a targeted boost to oxygen levels in the immediate vicinity of operations.
In summary, tunnels have oxygen primarily because they are open to the atmosphere and are equipped with ventilation systems. During construction, supplementary systems like oxygen dispersal units may be used to specifically enhance oxygen levels at the working face.
