The tunnel air duct fabric must have a product certificate before entering the site, and an external inspection must be carried out before application to ensure that there is no damage.
The tunnel ventilation duct cloth should be hung in a moderate location that does not harm the traffic of vehicles inside the tunnel. The hanging should have a necessary height to width ratio, which is not only beneficial for natural ventilation and engineering construction, but also for maintenance and management methods. Usually built at the arch line position during tunnel construction, it should also be placed at the top of the tunnel when the cross-section is low.
The distance between the inlet and outlet of the air blower and the excavation working face, theoretically speaking, requires that the pressure type natural ventilation excavation working face must be within the effective range of the ventilation duct. The size of the effective range is related to the diameter of the ventilation duct, wind force, cross-sectional specifications of the tunnel construction, and the suspension position of the ventilation opening, and should be calculated according to the basic theory of water jet.
Considering the actual effect of natural ventilation, it is required that the distance between the ventilation opening of the pressure type natural ventilation and the excavation working face should not exceed 15m. In the author's opinion, the inappropriate aspect is that, considering the actual effect of natural ventilation, theoretically speaking, the spacing should be within the effective range of sexual activity. However, due to the different construction characteristics of each project, its effective range is also different. Moreover, in practical application, the difficulty of layout of excavation face machinery and equipment should be taken into consideration, as well as avoiding damage to ventilation ducts caused by engineering blasting and rockfall. Therefore, the manipulation of the spacing between tunnel ducts not only takes into account the effective range of eroticism, but also considers the hazards of engineering blasting, layout design, and other practical applications. Each section of old ventilation duct should be installed at the end of the ventilation duct to reduce the impact of engineering blasting and damage to the tunnel construction blower caused by rockfall.