关键词: 双通道供风, 施工隧道, 最优风速, 粉尘疏散, 呼吸性粉尘

Abstract:

Aiming at the problems of matching of wind speed and difficulty in measuring the related characteristics of high deposited respirable dust in the double-channel air supply of the construction tunnel, taking a large section railway tunnel under construction as the research background, the return air vector characteristics under different wind speeds were tested. The multi-mode ventilation simulation analysis of the experimental tunnel was carried out by using the two-stage solution mode of ANSYS Fluent. The results show that the parameters in the numerical simulation are set correctly and the results are reliable. When the outlet wind speed V_f of auxiliary pipe is more than 9.5 m/s, the mean value of vector wind speed $\overline{V}_{\lambda}$ on the detection section P_i is negatively correlated with V_f. When V_f ≤ 9.5 m/s, $\overline{V}_{\lambda}$ and V_f are positively correlated. When V_f=9 m/s, the wind speed matching degree of the main and auxiliary air pipes is the best, and class I respirable dust has the highest dust reduction efficiency. Class I respirable dust is easy to gather around the trolley, and Class II respirable dust is more likely to pass through the lower space of the trolley and enter the backlog swirl area under the action of deflected airflow, resulting in long-term cluster aggregation of this type of respirable dust. Under the optimal wind speed matching condition, the impact of the return flow conflict on the swirl region is not obvious, but it still exists. During construction, additional ventilation and dust reduction equipment shall be arranged in the region.

Key words: double-channel air supply, construction tunnel, optimal wind speed, dust evacuation, respirable dust