CFD numerical simulation of tunnel dust pollution control using a negative pressure double extraction ventilation system

To effectively control the dust pollution problem in tunneling, we studied the dust control and removal effect of a novel negative pressure double extraction ventilation system. We first investigated the spatial and temporal evolution law of wind flow and dust under single-pressure entry ventilation conditions, and found that the dust diffused to the tunnel exit within 150 s. The average dust concentrations at the driver's location, the front of the tunnel, and the back of the tunnel were 339.26, 278.39, and 232.43 mg/m3, respectively, and the average dust concentration in the tunnel was 243.74 mg/m3. Subsequently, based on the principle of air extraction and dust control, a negative pressure double extraction dust control system was constructed. The spatial and temporal evolution of wind flow and dust at different locations of the exhaust duct was investigated. When the exhaust duct A was 3.0 m away from the floor of the roadway, CA=3.0 m, and when the exhaust duct B was 4.0 m away from the left wall of the roadway, CB=4.0 m, the average dust concentrations at the driver's location, the front of the tunnel, and the back of the tunnel were 45.62, 164.58, and 5.21 mg/m3, respectively. Compared with single pressure-entry type ventilation, the dust prevention effect of the system improved by 86.55 %, 40.88 %, and 97.76 %, respectively, and this installation position was determined to be the optimal position for dust removal.