Ventilation of tunnels during drilling using a forcing ventilation system - a case study

In Poland, more and more tunnels are being built using mining methods. Mostly ventilation systems are described for tunnels already commissioned. There are few examples of ventilation calculations for tunnels under construction. The paper shows a case study where calculations were made of the minimum air volume flow required to ventilate a tunnel during its tunnelling using four duct ventilation systems. The first system used two separate fans with a 1200 mm diameter duct line, the second system changed the diameter of the duct line to 1400 mm, the third system used one fan with two 1200 mm diameter duct lines connected in parallel, and the fourth system increased the diameter of the duct line to 1400 mm. Fan power requirements were determined for these layouts. The cost statement shows that it is advantageous to change the diameter of the duct line to a larger one - reducing the total cost by about 10%. With the assumed electricity prices, the more favourable variants are the systems for which two fans with separate duct lines are provided - a cost difference of about 5%.