Abstract: As the most complicated mined underground cavern group project in China, the Badaling Great Wall station has the characteristics of multiple caverns and working faces, as well as a complicated ventilation network. For ventilation during the station construction, a multistage scheme of forced, gallery, and mixed ventilations is proposed considering the dynamic changes in the wind network structure of the cavern group, and a numerical simulation method is employed to study the rationality of the ventilation scheme of long deadend heading. Subsequently, based on the measured data, the gallery and mixed ventilation status of the cavern group is analyzed using theoretical calculation and ventilation network solution results, and the influence of the windnetwork structure variation on the ventilation effect is clarified. Results show that: [JP2](1) The multistage ventilation design can meet the ventilation requirement during the station construction. (2) After blasting, the concentration of main air pollutants can meet the specified requirements when the tunnel is ventilated for 30 min. (3) Ventilation quality monitoring and network solution methods can effectively optimize the ventilation system and adjust the ventilation measures. (4) Air quality at the intersection of the tunnels and densely drilling and blasting areas can be significantly improved after using local fan and dedust equipment. The results can solve the problem of dynamic ventilation in a large underground station and achieve efficient air circulation during construction.

Key words: tunnel engineering, phased ventilation, ventilation network solution, Badaling Great Wall station, complex tunnel groups, numerical simulation