Study On The Influence Of Air Extraction From Inclined Shaft In Tunnel On The Safety And Comfort Of Train Operation

The new Wushaoling Tunnel of Lanzhou-Zhangye 3-4 Line Railway uses the adjacent existing Lanzhou-Wuwei Line 2 Wushaoling Tunnel inclined shaft to build a branch cavern for construction ventilation operations,which avoids repeated construction of ventilation inclined shafts,reduces the number of fans,shortens the ventilation distance,and reduces energy consumption.However,the aerodynamic effect in the existing tunnel becomes more complicated when taking air from the inclined shaft,which may adversely affect the safety of train driving and the comfort of passengers in the car.Therefore,in this paper,the aerodynamic safety and comfort of the trains in the case of wind extraction from the inclined shaft in the tunnel are studied in depth by means of data research,field tests,numerical simulation and theoretical analysis.Since the existing Wushaoling Tunnel of Lanzhou-Wuwei Line 2 is a very long tunnel(tunnel length 20.05km)and the operating speed is low(120km/h),the modeling and calculation time is long when using numerical simulation,which is not conducive to the comparison and analysis of multiple working conditions,so firstly,a shorter tunnel with a central ventilation inclined shaft is selected for numerical simulation to investigate the influence of the inclined shaft on the aerodynamic safety and comfort of trains.Then,the numerical calculation of the existing long tunnel with multiple ramps was simplified to verify the pneumatic safety and comfort of the operating trains.The main conclusions are as follows:(1)Through the calculation of train lift force,cross force and overturning moment when taking air from the inclined shaft,it is found that the indexes controlling train safety are cross force and overturning moment.The carriage cross force and overturning moment are proportional to the square of the wind speed,linearly inversely proportional to the speed,and decrease with the increase of the transverse distance between the train and the inclined shaft;when the train meets through the tunnel,the farther the meeting position is from the ventilation inclined shaft,the carriage cross force and overturning moment is smaller;The length of the existing tunnel does not affect the lateral force and overturning moment of the carriage;(2)The wind from the inclined shaft has no effect on the transient pressure of the train,the pressure inside the tunnel and the air resistance of the train,and the transient pressure inside the car,which is the index of controlling the pneumatic comfort of the train,has nothing to do with whether the wind is taken from the inclined shaft or not;(3)In summary,the assessment of the aerodynamic safety and comfort of trains operating in the existing Wu Shaoling Tunnel only requires the simulation of the most unfavorable operating conditions at the highest speed and the maximum wind extraction speed of all interconnecting inclined shafts.The results show that the aerodynamic safety and comfort of trains in the existing Wu Shaoling Tunnel meet the standard requirements;(4)The ventilation scheme of the new WuShaoling tunnel using inclined shafts to take air from the existing tunnel can not only ensure that the concentration of harmful gases in the construction tunnel meets the standard,but also ensure the pneumatic safety and comfort of trains operating in the existing tunnel,and reduce the ventilation energy consumption and construction costs,which has a high value for promotion and application.Wu Shaoling tunnel meet the specification requirements,and the hazardous air concentration in the construction tunnel meets the construction requirements.