关键词: 隧道工程, 高海拔隧道, 施工通风, 压入式通风, 合理通风长度

Abstract: There are many challenges in the construction of long tunnels in high altitude areas. Ventilation in the construction of long tunnels at high altitude under the conditions of low pressure and low oxygen content is an important research topic. In the existing engineering practice of construction ventilation of long tunnels at high altitude, the ventilation mode of combination of the forced type and roadway type was mostly adopted, and the length of forced ventilation section was determined only by construction experience and construction task. The theoretical research on the demarcation of length between the forced type and roadway type was rare. At present, the research on the forced ventilation distance mainly focused on the analysis of the limit ventilation distance under specific conditions, which was a lack of direct calculation of the forced ventilation length without considering the construction process. Based on the principle of flow conservation, combining with the experience of the forced ventilation in tunnel construction in low altitude areas, the optimal length correction formula of tunnel forced ventilation in high altitude area was obtained. Based on the theoretical formula used in the construction of Mila Mountain Tunnel Project, the ventilation scheme was developed, and the dust concentration and CO concentration in the tunnel at 30 minutes after excavation and blasting were monitored and recorded on site. The feasibility of the theoretical formula was verified by analysis.

Key words: tunnel engineering, high altitude tunnel, construction ventilation, forced ventilation, optimal ventilation length