Optimisation of synergistic ventilation between dust and gas in a gas tunnel

In view of the difficult problem of gas and dust exceeding the limit during the digging process of a gas tunnel in Guizhou Province, Southwest China, the CFD numerical simulation method was applied to study the gas tunnel airflow, dust and gas transport law during the digging process. A physical simulation experimental platform was established to verify the numerical simulation results, and research was carried out in terms of gas-containing gas-carrying dust disaster prevention and control, and ventilation optimization was carried out for this gas tunnel. The results showed that the maximum gas concentration in the tunnel face under press-in ventilation could be about 1%, and the local dust concentration can be up to 900 mg/m³. The gas mass fraction in localised areas of the tunnel exceeded 0.9% under mixed ventilation pressure-extraction ratios of 9:1 and 8:2. When the pressure to pumping ratio is 6:4, the dust was concentrated on the return side of the tunnel at a distance of 40-60 m from the head of the tunnel, and the highest local dust concentration reaches 700 mg/m³. When the pressure pumping ratio was 7:3, the dust pollution problem could be controlled more effectively, and at the same time, there was no higher concentration of gas gathering in the tunnel. A comprehensive analysis of the differences between dust and gas-enriched areas in gas tunnels could provide some guidance on the synergistic control of gas and dust in gas tunnels.