The optimization of a dust suppression and clean production scheme in a TBM-constructed tunnel based on an orthogonal experiment

Abstract

This study aims to examine whether clean production can be achieved by using a ventilation dust removal system in a tunnel being constructed using a tunnel boring machine (TBM). The section between the Guizhou-Road Station and the Guipaijing Station on the No. 1 line of the Qingdao Metro was selected as the study area, and the effectiveness of a ventilation dust removal system on the diffusion distance and mean concentration of dust in the excavating area was investigated through the use of a CFD-based numerical simulation. Firstly, it was found that when the first pressure quantity, exhaust quantity, and position of the pressure inlet and exhaust inlet of the ventilation dust removal system all remained unchanged, the secondary pressure quantity corresponding to the optimal dust suppression effect was determined to be 8 m³/s. Next, an orthogonal experiment was performed on the position of the pressure inlet and exhaust inlet and the forced-to-absorbed airflow quantity ratio in order to examine the effect of different combinations on the dust suppression effect in the tunnel. By selecting the dust diffusion distance, mean dust concentration in the tunnel and dust-collecting efficiency as the evaluation indexes, three favorable schemes were determined, from which the optimal scheme was selected. In the optimal combination, the secondary pressure inlet and exhaust inlet were 28 m and 11m away from the tunnel face respectively and the forced-to-absorbed airflow quantity ratio was 1.6. After the scheme’s optimization, the dust diffusion distance in the tunnel was shortened considerably by 53 %, the mean dust concentration was reduced to 1.52E-06 kg/m³, and the dust-collecting efficiency was enhanced by 13.19 %. Under these optimal conditions, a ventilation dust removal system can maximize the operational efficiency and ensure a clean air environment during any production activities.