| With the vigorous development of society,the transportation industry has gradually developed,and the appearance of tunnels has shortened the distance between the two places,bringing great convenience to people’s travel and cargo transportation.In the process of tunnel excavation,it is inevitable to face the problem of heat and humidity environment and pollutant concentration in the tunnel.How to solve the problem reasonably and quickly is the necessary condition to ensure the personal safety of the tunnel workers.In this thesis,the construction section of inclined shaft 1 of a construction tunnel in Ningbo is used as the support object,and the field measurement of various working conditions in each period of the tunnel is carried out,and the relevant information is statistically analyzed for CFD simulation.The results are summarized as follows:First of all,the tunnel ventilation system is designed for inclined shaft 1construction section.Through summarizing the working conditions of construction personnel and engineering vehicles in the tunnel,the minimum air demand under different procedures of construction tunnel is obtained by combining the relevant calculation formula of air demand.According to the change of tunnel construction length,the tunnel construction is divided into three stages,and different ventilation schemes are designed for the three stages by changing the position of axial fan,the position of air pipe and the length of air pipe.Combined with air leakage rate,air supply volume,tunnel flow resistance,the selection of axial flow fans in three stages of construction tunnel is carried out,and finally the number and type of axial flow fans are suitable for the three stages of construction tunnel.Secondly,taking the construction section of inclined shaft 1 of a tunnel in Ningbo as the supporting project,field measurements were carried out on the reinforcement process,drilling process,blasting process and slag discharge process of the supporting tunnel.Through calculation,the wind speed at the end of the supply air is 17.83m/s,and the 100-meter air leakage rate of the pipeline is 0.14%.Through the analysis of the thermal and humid environment,pollutant concentration,air supply volume and air leakage rate in the tunnel.The change law of the thermal and humid environment and pollutants in the tunnel with time and along the tunnel were obtained.Finally,CFD software was used to simulate the blasting process relying on the project,and the changes of wind velocity vector at different levels and heights were analyzed by selecting appropriate turbulence models,governing equations and simulation algorithms,and the spatio-temporal changes of CO in the tunnel were analyzed.By changing the size of exhaust air volume in the tunnel,the position of exhaust air outlet and the position of jet fan,26 times of tunnel ventilation optimization simulation were obtained.By changing the exhaust air volume and the position of exhaust air outlet,it was concluded through comparative analysis that when the exhaust air outlet distance was 5m deep in the inclined shaft and the exhaust air volume was 35m3/s,the discharge effect was the best.On the basis of the above optimization of ventilation,the jet fan is installed in the inclined shaft of the tunnel to carry out effective air dredging,and through the optimization simulation of the jet fan at different positions in the inclined shaft for 5 times,the final result is that the discharge effect is best when the jet fan is 120 m away from the main hole. |
PDF Full Text Request