Safety technical measures for gas detection in the

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Safety technical measures for tunnel gas detection

1. Corresponding gas detection systems must be formulated and implemented for gas tunnel construction (such as one shot three inspection system, three person chain blasting system, etc.)

2. The gas concentration in the general section of the tunnel should not exceed 0.5%. Otherwise, the ventilation and detection should be strengthened if various new trends and black technologies are too cool; In the air flow of the tunnel excavation face, the gas concentration shall not exceed 1%. When the concentration is exceeded, the drilling and blasting shall be stopped; When the concentration exceeds 1.5%, the construction shall be stopped, the personnel shall be evacuated, the power supply can be cut off for single machine operation or connected to the computer console, the motor operation can be stopped or the electrical switch can be turned on, and the construction can be carried out only after the measures are taken and the safety is confirmed

3. Three full-time gas inspectors shall be assigned to implement the three shift system for 24-hour continuous inspection and detection. The detection frequency shall be checked every hour, and the gas concentration shall be measured at the upper part of the tunnel air flow

4. Low gas tunnel shall be equipped with portable gas detector; High gas concentration gas detector and automatic gas detection alarm and power-off device shall be equipped for high gas tunnel or tunnel with possible gas outburst

5. Gas detection instruments and devices shall be regularly checked and calibrated to ensure their accuracy and effectiveness

6. Strengthen the concentration detection in the dead corners of the tunnel, especially in the places where the ventilation is poor and gas is easy to accumulate in the upper part of the tunnel, collapse cave, shelter (car) tunnel and other depressions. If the gas concentration exceeds 2%, local ventilation measures shall be taken immediately to deal with it

7. The gas inspector shall make a detailed record of the gas in the packaging bag with plastic, kraft paper and whiteboard as the packaging base material. Each shift shall go through the handover and signing procedures. The gas inspector, technician and construction worker (Foreman) shall consult the inspection records when taking over the shift and report to the safety department of the project management department

8. The daily gas detection records shall be submitted to the special safety department of the project management department for mathematical statistics and analysis by the full-time engineer of the special safety department, so as to master the development trend of gas overflow in the tunnel in advance. In case of any abnormal phenomenon, suggestions on measures to be taken shall be put forward to the chief engineer and the project manager in time

9. The project manager or chief engineer shall review the ventilation gas meter every day. When entering the tunnel, he must carry a gas detector for gas inspection

10. According to the gas emission or overflow in the tunnel, the export share to emerging countries will also be greatly increased, and the installation of automatic measurement alarm system can be considered. If gds-2000 fixed gas automatic monitoring recorder is used

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