Study On The Environmental Characteristics Of Mountain Highway Tunnel Construction And The Improvement Measures Of Smoke And Dust Elimination Lighting

In order to improve the air environment during tunnel construction,this paper takes the construction project of PW Mountain Highway Tunnel in Gansu Province as the background,aiming at the characteristics of tunnel and temporarily aiming at the tunnel excavation distance is not long enough.In order to reduce the concentration of particulate matter such as dust and smoke in tunnels and improve the air environment in tunnels,the way of pressure ventilation is adopted to ventilate and remove dust in tunnels.Based on computational fluid dynamics theory,gas-solid two-phase flow theory and turbulence model theory,the following mathematical models are established by ANSYS numerical simulation software.(1)Computational Fluid Dynamics(CFD)is used to simulate the wind velocity distribution in Z direction along the X-Z plane(180m)and in Z direction in X-Y plane(10m apart from the tunnel face)after the opening of the tunnel ventilator.The causes of the distribution of the flow field in different planes of the tunnel are analyzed.(2)Simulate the concentration nephogram of dust and particulate matter on the X-Z plane(180m)along the whole tunnel ventilation process under three conditions of blasting,shotcrete and slag loading;simulate the concentration distribution of dust and particulate matter on the face of the tunnel under three conditions of blasting,shotcrete and slag loading;simulate the time-varying nephogram of dust and particulate matter on the face of the tunnel under three conditions of blasting,shotcrete and slag loading;After 10 minutes ventilation and dust removal,the dust concentration distribution in the X-Y plane every 10 meters within 100 meters of the tunnel face was mapped.(3)The numerical simulation of the pressure ventilation under the conditions of blasting,shotcrete and slag loading of the tunnel shows that the ventilation effect is good.Therefore,the pressure ventilation method is adopted to remove dust and dust from the tunnel construction and improve the air environment quality.(1)Monitor the changes of dust and particulate matter concentration in the face of face with ventilation time during ventilation under three conditions of blasting,shotcrete and slag loading respectively.(2)After 10 minutes of ventilation under three conditions of blasting,shotcrete and slag loading,a monitoring point is arranged every 10 meters from the palm surface to monitor the dust and particulate matter concentration at each point.The concentration of dust and its particulate matter has been greatly reduced to 2mg/m3 under the control standard of dust concentration within 10 seconds to 1 minute of ventilation under the three conditions of blasting,shotcrete and slag loading respectively.Through monitoring the concentration of dust and its particulate matter in the tunnel after 10 minutes ventilation under the three conditions of blasting,shotcrete and slag loading respectively,the measured concentration of dust and its particulate matter has been lower than that in the tunnel.Dust concentration control standard is below 2mg/m3 in road construction environment.In order to improve the lighting environment in the tunnel construction environment,the lighting situation in the tunnel construction environment is simulated by using optical lighting theory and DIAlux optical lighting software based on the construction project of PW Mountain Highway Tunnel in Gansu Province.The lighting fixtures are set as high-pressure sodium lamp and arranged at the top of the tunnel and along the central axis.The distribution of the overall light intensity of the tunnel is simulated and calculated,and the reasons for the formation of the distribution of the overall light intensity in the construction tunnel are analyzed.In order to test the lighting improvement effect of the construction tunnel,monitoring points of light intensity are arranged on the spot to monitor the light intensity.The monitoring results show that the illumination intensity of the monitoring point is greater than that of the simulated ground,and the reasons are analyzed.Through on-site monitoring of light intensity under tunnel construction environment,it can be seen that the measured light intensity meets the needs of construction operation and the improvement effect is good.