The dust pollution characteristic after tunnel blasting and related influence parameters by using experimental method

The advancement of extra-long tunnel building has led to a corresponding deepening of construction ventilation technology. However, dust pollution created by drilling and blasting construction has become one of the serious obstacles to improving the construction environment. This paper employs the model test as the primary research methodology to investigate the diffusion characteristics of heterogeneous dust groups with varying scales under the influence of the ventilation airflow field in the construction of the extra-long railway tunnel. First, an equal scale (1:21) model is built based on the standard section of the long double-track railway tunnel and the resemblance criterion. Second, the ventilation system and dust generator were assembled in accordance with the actual project, and the effects of different initial dust volume, return air rate, and second lining step on key characteristics such as dust peak concentration, diffusion rate, and dust suppression efficiency were discussed. The final research findings are intended to provide theoretical direction for dust suppression technologies in the construction of extra-long railway tunnels. The model test results demonstrate that when the initial dust concentration is greater than 150 mg/m3 during tunnel construction, it is rather difficult to discharge dust. Keeping the return air wind speed in the tunnel above 1 m/s can significantly reduce energy consumption while maintaining ventilation. When the trolley is positioned 90 m from the tunnel face, the lag impact on dust in the tunnel is apparent.