Song Jinshen, Liu Jie, Liu Xiaojun
To reveal the diffusion patterns of dust during tunnel construction by the drilling and blasting method, this study takes the Zijingyaoshan Tunnel of the new Liuzhou-Wuzhou Railway as the engineering background. Based on the theory of gas-solid two-phase flow, a full-scale numerical model of the tunnel's wind-dust environment was established using the computational fluid dynamics (CFD) method. The effects of different construction procedures (blasting, mucking, shotcreting, drilling), excavation methods (full-face, two-step bench, three-step bench), rock types (sandstone, mudstone), and blasting parameters (low, medium, high charge) on the spatio-temporal diffusion characteristics of dust were systematically simulated. The results indicate that:(1) Blasting operations generate the highest dust concentration, with concentrations during the mucking, shotcreting, and drilling stages being 75.61%, 85.59%, and 96.98% lower, respectively, compared to the blasting stage. (2) The excavation method significantly impacts dust concentration; compared to the full-face method, the two-step and three-step bench methods reduce dust concentration by 19.90% and 33.90%, respectively, after 5 minutes of ventilation. (3) Mudstone, being more easily fractured, produces finer particles with higher suspensibility, leading to wider diffusion ranges and higher concentrations; the dust concentration in sandstone conditions is 34.89% lower than that in mudstone. (4) The high explosive charge yields the maximum dust generation, with the medium and low charges resulting in 34.64% and 75.03% less dust generation, respectively, compared to the high charge. The findings can provide a scientific reference for the optimal design of dust suppression measures, such as the placement of spray systems, at tunnel construction sites.
