Analysis Of The Influence Factor On Compression Wave By A High-speed Train Entering A Tunnel And Corresponding Buffer Structure

When a train enters a tunnel, a compression wave is generated and propagated through the tunnel. At the moment the compression wave arrives at the tunnel exit, an impulsive pressure wave radiates out of the tunnel exit toward surrounding area. According to acoustic analysis,the influence is proportional to the maximum compression wave gradient. Consequently,we use the numerical method to simulate the process of train entering tunnel. The results show a good fit with the experiments of former researches.On this base, further simulation and analysis about velocity,blockage rate,nose shape and nose length were taken. Based on the previous research,a formula which establishes the relation between maximum compression wave gradient and the influence factors was proposed.In the latter half, this paper proposed two buffer structures: baffle structure and open hood structure. The ratio of maximum compression wave gradient with buffer structure on the maximum compression wave gradient without buffer structure was used to evaluate the buffering effect. Based on the evaluation criterion, lots of sizes of buffer structures were analyzed.At last, the size of buffer structure was optimized and achieved the goal of weakening the maximum compression wave gradient effectively.