Research On The Influence Of Line Connection On Metro Piston Wind And Air Temperature

With the acceleration of my country’s urbanization process,the increase in the number of urban populations has put more and more pressure on urban transportation.Metro traffic with large passenger capacity,fast speed,punctuality,comfort,low energy consumption,and low pollution has become an important channel to alleviate urban traffic pressure.In recent years,my country’s subway traffic has developed rapidly.The scale of subway lines in various cities has continued to expand and gradually form a network.The lines in the subway line network are connected,and there is air exchange and heat exchange between the lines.As a result,the tunnel piston wind and air temperature after the line-connected are different from those before the line-connected.Studying the influence of line connectivity on subway piston wind and air temperature is of great significance to ensure the safety of subway networked trains and personnel.This thesis takes a screen-door subway in Xi’an as an example.SES was used to analyze the relationship between the influence of line connectivity on piston wind and air temperature and the number of model stations.A simplified model of two-line connectivity was established.That the basic characteristics of piston wind and air temperature changes after the line-connected and before connected is analyzed aiming at the simplified model.The results show that:the influence of line connection on the piston air volume is mainly at a station which before and after the connecting station in each section;that the piston air volume of the tunnel in the section where the tie line is located is most affected;the air volume of the most affected areas of the two lines is reduced by 35.8m~3/s and 32.3m~3/s;the total air exchange rate between the tunnel and the outside is less affected by the line connection,after the connection,the total air exchange rate is reduced by 5m~3/s;the air exchange between the lines is alternately positive and negative,and the net air exchange rate is 37.3m~3/s;the air temperature of the tunnel is affected by the line connection more than the piston air volume,the maximum temperature rise is 1.28℃,and the maximum temperature rises 0.33℃;the heat exchange between the two lines and the outside varies greatly,respectively-1470.4k J/s and 1609.0k J/s,line A loses heat through the tie line 1547.3k J/s,line B gains heat through the tie line 1536.5k J/s,the total heat transfer of the two lines changes very little,increasing by 76.9k J/s and respectively 72.5k J/s.For the dual-piston system,the influence of the line connection on the piston air and air temperature is explored when the air shaft structure design parameters,tie line design parameters,blockage ratio and rail exhaust volume change.The results show that the maximum piston air volume change is greatly affected by the air duct resistance coefficient,the cross-sectional area of the piston air shaft,the length of the tie line,the cross-sectional area of the tie line,the position of the tie line and the blocking ratio.When the cross-sectional area of the piston air shaft is 32m~2,The piston air volume change reaches the maximum-42.2m~3/s;the tunnel air temperature rise value reaches the maximum when the blocking ratio is 0.3,and the maximum value is 2.0℃;the maximum air temperature change value of the tunnel is in the cross-sectional area of the piston air shaft It reaches the maximum at 32m~2,and the maximum value is 0.8℃.For the single-piston system,the influence of the line connection on the piston wind and air temperature is explored when the air shaft structure design parameters,and tie line design parameters and blockage ratio change.The results show that the maximum piston air volume change is greatly affected by the air duct resistance coefficient,the cross-sectional area of the piston air shaft and the blocking ratio.When the piston air shaft cross-sectional area is 32m~2,the piston air volume change reaches the maximum,and the single piston at the exit end The maximum value of the system is-22.7m~3/s,and the maximum value of the single-piston system at the inbound end is-17.5m~3/s;the increase in tunnel air temperature and the change in the maximum air temperature in the tunnel reach the maximum when the blocking ratio is0.3.The maximum air temperature rise of the single-piston system at the end is 0.6℃,the maximum change in the maximum air temperature is 0.44℃,the maximum air temperature rise in the single-piston system at the inbound end is 1.2℃,and the maximum change in the maximum air temperature is 0.33℃.