Numerical Simulation of CO Distribution in Construction Area of Single-Shaft and Multi-Face High-Cold Highway Tunnel

The distribution of carbon monoxide in the tunnel construction area affects construction safety. In this paper, numerical simulation (CFD) was used to analyze the influence of temperature on CO distribution in the construction area of large-section and high-cold highway tunnels. Based on the East Tianshan super-long highway tunnel, an inclined single-shaft and four-face CFD model in a 1:1 ratio was established, The length of the inclined shaft is 1,560.03 m. This paper analyzed and compared CO distribution in summer and winter. After 30 min stable ventilation, CO had a weak adherence phenomenon on the side wall near the working surface which the maximum value was 50.02 ppm. And there was a stratification phenomenon of CO in the inclined shaft. The CO near the top wall was 50.36 ppm. The CO near the bottom wall was 42.20 ppm. Besides, the increase of temperature makes the adherence phenomenon and stratification phenomenon more obvious. Then, the paper analyzed the reasons why CO gathered at the corner of inclined shaft. Finally, the paper found the key monitoring areas of CO. Optimization suggestions were given, which are changing the local shape of the tunnel bend or adding jet fans at the bend of the inclined shaft.