How is the leakage of toxic and hazardous gases monitored and prevented during tunnel boring machine construction? During tunnel boring machine construction, monitoring and preventing the leakage of toxic and hazardous gases is crucial for ensuring the health and safety of workers. The following are some effective monitoring and prevention measures:

   I. How to Effectively Detect Toxic and Hazardous Gas Leaks

   1. Use of Gas Detection Equipment: Install fixed or portable gas detectors in the construction area. These devices can monitor the concentration of toxic gases in the air, such as methane, carbon monoxide, and hydrogen sulfide, in real time. Once a gas concentration exceeds a safety threshold, an alarm is immediately issued.

   2. Optimize the Ventilation System: Ensure the construction area has a good ventilation system, using natural or mechanical ventilation to dilute and remove hazardous gases. When working in enclosed or semi-enclosed spaces, special attention should be paid to the installation of ventilation facilities.

   3. Environmental Monitoring: Monitor the environment surrounding the construction area to assess whether there are any external gas sources, such as nearby industrial emissions or underground reservoirs.

   4. Apply Technological Innovation: Explore the use of new monitoring technologies, such as fiber optic sensing and wireless sensor networks, to improve monitoring accuracy and coverage.

   II. Measures to Prevent Toxic and Hazardous Gas Leaks

   1. Regular Testing and Maintenance: Conduct regular gas testing at the construction site, especially before entering a new work area. Gas detection equipment should also be regularly calibrated and maintained to ensure its accuracy and reliability.

   2. Safety Training: Provide safety training to workers regarding the hazards of toxic and hazardous gases, ensuring they understand the potential risks and master the proper use of personal protective equipment and emergency response procedures.

   3. Use of Personal Protective Equipment (PPE): Provide appropriate personal protective equipment, such as respirators and gas masks, and ensure workers wear them properly when entering potentially hazardous areas.

   4. Adjustment of Work Plans: Adjust work plans based on geological conditions and available monitoring data, avoiding prolonged work in high-risk areas or implementing methods such as segmented construction and alternating work to mitigate risks.

   5. Development of Emergency Plans: Develop a detailed emergency plan, including evacuation routes, assembly points, and emergency contact information in the event of a gas leak. Conduct regular drills to ensure all personnel are familiar with emergency response procedures.

   Through the comprehensive application of the above measures, the leakage of toxic and harmful gases during tunnel boring machine construction can be effectively monitored and prevented, thereby ensuring the health and safety of operators.