Technologies on Safe Construction Ventilation of Long-large Shield Tunnel with Low Gas in Metro

Taking the project of long-large shield tunnel with low gas in Xingtian section of Chengdu Metro Line 18 as an example, A new construction ventilation method is established, which includes: the main tunnel ventilation with axial fans installed at the entrance of the tunnel and the local ventilation with jet fans installed in the shield and at the upper part of the bridge and the top of the 4# trailer for the rear supporting system; the connecting passage ventilation with a jet fan installed on the wall; the crossing ventilation with a jet fan installed in the middle of tunnel. The ventilation technology for safe construction of Metro long-large shield tunnel with low gas is established after detailed calculation of the fan selection, which is applied to finish safely and quickly construction task, and which provides reference for similar projects in the future.