Study On Harmful Gas Analysis And Energy-Saving Ventilation Technology For Asphalt Pavement Construction In The Long Tunnel

Ventilation is an essential factor restricting construction during the asphalt pavement of long tunnels.Efficient ventilation equipment configuration can not only improve the construction environment with high-temperature,high smoke and low visibility,but also ensure the health of construction workers,improve construction quality and save energy.At present,the study on ventilation technology in asphalt pavement of the long tunnel is relatively lacking.In this paper,the tunnel asphalt pavement energy-saving ventilation system is established for the environmental pollution of asphalt pavement construction in the long tunnel.The system can adjust the air volume of the fan output according to different pollution levels,ensure energy-saving ventilation during the tunnel asphalt pavement construction.By analyzing the construction process characteristics of the tunnel asphalt pavement,the main pollutants in the tunnel asphalt pavement construction are the construction machinery exhaust gas and the asphalt mixture flue gas.The main pollutants discharged from high-temperature asphalt mixture are asphaltic acid,benzene soluble matter and benzo [a] pyrene;the main pollutants discharged from construction machinery are CO,NO,NO2,SO2 and HC.During the paving process,it is easy to form a construction environment with high temperature,high smoke and low visibility.In the absence of external wind pressure,the FLUENT and COMSOL finite element software were used to simulate the air heat and mass transfer in the asphalt pavement space,and the field test was carried out.The results show that when the temperature of asphalt mixture is higher than 140 °C,the emission rate of harmful substances is faster;the air flow in the paving process is disordered.In the working area of the construction personnel,within 2 meters from the bottom of the tunnel,the air temperature is easy to exceed 40 °C,and the concentration of harmful substances is high.The ventilation heat balance equation and the pollutant dilution equation are derived by the formula to describe the variation of the construction space environment during the ventilation process.By analyzing the working characteristics of a single fan and multiple fans,the combined working characteristics of the fan are obtained,and the position of the fan on the paving surface is laid according to this characteristic.Since the natural wind of the long tunnel is rich,the natural wind direction of each section of the tunnel is monitored during mechanical ventilation,and the strategy of utilizing natural wind is determined.Based on the fan frequency conversion technology,BP neural network algorithm,fuzzy PID algorithm and OR gate control loop are used to establish a tunnel asphalt pavement ventilation energy-saving system.By monitoring the tunnel environmental parameters,the ventilation volume of the pavement space is controlled.Relying on the physical engineering,the system is simulated by Matlab software,and the BP neural network algorithm is used to process the sensor monitoring data;the fuzzy PID algorithm is used to control the frequency converter to adjust the air supply volume of the main fan;combined with the OR gate circuit to control the number of auxiliary fan opening To achieve energy-saving ventilation during tunnel paving.The simulation results show that the system responds quickly and the control effect is good.