The Cushioning Properties Research Of High-speed Railway Tunnel

In recent years, with the train speed increases, the aerodynamic effects became more andmore serious in the high-speed railway tunnel. Pressure fluctuations lead to physicaldiscomfort of passengers and maintenance personnel in tunnel, Meanwhile, Micro-pressurewave will cause environmental problems at the exit of the tunnel. Currently, there are plentyof aerodynamic mitigation measures, But there will be many constraints in their practicalapplications, so it is necessary to have a further study of other mitigation measures. The mainachievements of this paper are described as follows.The mitigation measures and their shortcoming are reviewed, and the feasibility that thepressure wave can be reduced by changing the lining forms is given; The key that reducingthe initial compression wave can ease the aerodynamic effects is pointed out in this paper;one-dimensional compressible non-steady flow model is established according to the flowarea characteristics of high-speed train entering the tunnel, The initial compression waveunder different tunnel conditions is researched specially by numerical simulation: The valueof initial compression wave pressure, the pressure chart of the measuring points and the totalpressure diagram of tunnel are obtained under the following situations, with or without thevariable cross-section lining, different locations of variable cross-section lining, and differentrates of variable cross-section lining. the following conclusions are obtained throughcomparative analysis.（1）The initial compression wave,which is produced by a moving high-speed train inthe tunnel with no buffer, is the root of the pressure fluctuations in tunnel and themicro-pressure wave in the exit of the tunnel area.（2）The aerodynamic effect can be eased by using the variable cross-section tunnellining in high-speed railway tunnel. Compared with ordinary tunnel,the pressure gradient and the pressure value of compression wave is more lower by using the variable cross-sectiontunnel lining.（3）Different locations of variable cross-section tunnel lining would produce differentpressure values in tunnel. We can always find the appropriate location of variablecross-section tunnel lining, in which the pressure value is minimum in tunnel.（4）Different rates of variable cross-section lining also would produce different press-ure values in tunnel. In a certain range, the pressure value decrease while the rate of variablecross-section lining increase. If we continue to increase the rate of variable cross-sectionlining, the pressure values don’t change significantly. The ideal rate of variable cross-sectionlining is about1.1.