Study on the Distribution Characteristics of Pollutants Concentrations during Maintenance Period of Underground Water Conveyance Tunnel
In underground long-distance water conveyance tunnels,there is a significant accumulation of algae and Limnoperna fortunei,which are sessile aquatic organisms,on the inner walls.When water flow is halted for maintenance,these organisms dehydrate and die,releasing large quantities of harmful gases and posing a risk to the safety of maintenance workers.Investigating the distribution characteristics of pollutants within these tunnels is crucial for optimizing ventilation design during construction and enhancing the safety of maintenance workers.This paper establishes a ventilation calculation model for water conveyance tunnels under the condition of mechanical ventilation in working wells.The model is based on the actual tunnel structure and the design parameters of the ventilation system.The relationship between pollutant concentration,wind speed,and ventilation distance was investigated using the theory of turbulent flow in cylindrical pipes,boundary layer theory,and numerical calculation methods.The results show a strong correlation between pollutant concentration and ventilation speed.The relationship between concentration of pollutants c and section wind speed v is:c∝v-1,the relationship between concentration of pollutants c and ventilation distance x is:c∝x,when the section wind speed increases from 0.15 m/s to 0.30 m/s,the concentration of pollutants in the same section can be reduced by 50%By increasing the cross-sectional wind speed or reducing the ventilation distance,the concentration of pollutants in the tunnel can be effectively reduced,thereby preventing the accumulation of pollutants in the water conveyance tunnel.
Water conveyance tunnelContaminant diffusionFitting functionNumerical simulation
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