Research On The Law Of Piston Wind Flow In Extra-long Railway Tunnel Based On Ventilation Network Analysis

Based on the Gaoligongshan tunnel and the Bohai Strait cross-sea tunnel,this paper uses theoretical analysis and numerical calculations to study the law of wind flow caused by the train piston wind in the extra-long railway tunnel.The research results are as follows:(1)Based on the basic assumption of tunnel ventilation and the basic law of wind flow in tunnel ventilation network,the mathematical model of the calculation of ventilation network of railway tunnel is studied by using the Skod-Hensley method.The expression of the piston wind pressure in the railway tunnel is studied.The general formula of the correction formula of the loop air volume in the railway tunnel ventilation network is derived by using the formula and the mathematical model.And the calculation program of the ventilation network is compiled accordingly.The program obtained in this paper can be used to calculate the ventilation network of complex forms of extra-long railway tunnels,such as tunnels including multiple shafts and inclined shafts,multiple pressure releasing channels,multiple cross passages,multiple connected aisles or multiple trains.Further,it can be used to systematically,macroscopically and dynamically study the state and regularity of the piston wind flow in such complex forms of extra-long railway tunnels,and provide guidance for the development of ventilation schemes during tunnel operation and smoke extraction schemes during fires.(2)Based on the Gaoligongshan tunnel,the ventilation network calculation program is used to calculate the law of the wind flow caused by the piston wind in each section of the tunnel and the two shafts when the train is driving at different positions in the extra-long railway tunnel with double shafts.And the calculation results of the ventilation network calculation program and the theoretical formula are compared to verify the reliability of the ventilation network solution model and program.(3)Based on the Bohai Strait cross-sea tunnel,the ventilation network calculation program was used to calculate various working conditions,such as one-way driving of a single train,two-way driving of two trains,one-way driving of multiple trains and two-way driving of multiple trains.And according to the calculation results,the law of piston wind flow in the extra-long railway tunnel with multiple pressure releasing channels is studied,and the influence of factors such as pressure releasing channel,number of trains,driving direction and train meeting on the law is explored.