Transient CFD modelling of space-time evolution of dust pollutants and air-curtain generator position during tunneling

With the ongoing enhancement in the tunneling capacities of tunnel boring machines, the efficiency of tunneling has greatly improved. However, the increased tunneling capacity of these machines has brought additional problems, including increased challenges linked to workers' health, as well as environmental implications. Therefore, it has become increasingly important to improve both the sustainability of the tunneling environment and technical approaches to cleaner production. The main purpose of this research was to investigate the influence of air-curtain generators on the control of dust pollution in driving tunnels. A combination of numerical simulation and field measurements was used to study the diffusion properties of dust pollution generated without an air-curtain generator and when using an air-curtain generator placed in different positions. The results showed that, without an air-curtain generator, dust diffusion cannot be effectively controlled, dust pollution spreads widely, and workers' health and safety are seriously compromised. Following the installation of air-curtain generators in different positions, the diffusion of dust can be controlled to varying degrees. Various positions were tested and it was found that when the distance from the air-curtain generator to the cutting face, L-e, was 20 m, the optimal air purification effect was obtained, the dust concentration in the tunnel was C-d< 10(-5) kg/m(3), and the working environment for tunnel workers was clean and comfortable. Such an approach meets the requirements of providing cleaner production in driving tunnels and improving their environmental sustainability. This research therefore provides new insights into the environmental sustainability of tunneling activities. (C) 2019 Elsevier Ltd. All rights reserved.