No abstract

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.

Abstract-A novel conditioning and recording system of Lownoise underwater acoustic signal is proposed in order to coordinate the applied vector hydrophones. The low-noise analog circuit design is taken into account seriously according to the requirements of high precision and low distortion of underwater acoustic data. Compared with other similar systems, it features on miniaturization, high dynamic range, low distortion and low power consumption.

Taking the large-diameter shield cutter head between Xinglong Station and Tianfu new station in Civil Engineering Section 4 of Chengdu metro line 18 as an example, the numerical simulation is carried out by finite element software to analyze the stress and deformation of large-diameter shield cutter head under different loads in upper soft and lower hard strata. The results show that the stress and deformation of cutter head meet the design requirements, which can provide certain reference value for similar projects in the future.