Noise Characteristics Analysis Of The Entrance Of Sui-Yu Railway Tunnel

Environmental noise caused by the rail traffic has been a problem for a long time, although it had been researched in different angles, multiple methods both at home and abroad, but the research on the noise of the railway tunnel entrance was mostly concentrated in the aerodynamic characteristics of high speed railway tunnel by us, the noise characteristics of speed less than 200 km/h has not been seen frequently. So Chinese railway noise prediction model is applied in this paper to predict the noise of the Gujiayakou tunnel of Sui-yu raiway, the field monitoring results and predicted results were analyzed after the measured test. It concluded the noise characteristics and the regulars of attenuation of two different trains passed through the tunnel after studying the measured index changing with the related variation. The main results of the thesis are as follows:1. The monitoring noise result has no big difference compared with the predicting result, which means the Chinese railway noise prediction model is suitable for the prediction of the speed of 160 km/h CRH1A and CRH1B bullet trains to pass the tunnel.2. The noise of the speed of 160 km/h trains is decreased gradually as the distance increased, but part of the spectrum of it will rebound at a specific distance of the long train(CHR1B), and the rebounded distance are generally between 30-45m. The attenuation of the low frequency noise is faster than the high frequency with distance changes, the noise frequency is concentrated in the 80-5000Hz, whose area is wider when the trains enter compared out, and long train(CHR1B) is wider than the short(CHR1A) in the same distance. The noise linear pressure of long train is less than the short near the tunnel, which is opposite far from the tunnel.3. The micro pressure waves caused by the pass of the trains through tunnel take about 50s, whose fluctuation cycle takes about 1.7s and main frequency is 0.05-4Hz. The sound linear pressure level on the test section is decreased as the distance increased without rebound in the whole process and its frequency of the maximum level are all 1.25Hz at different measuring points.4. The horizontal noise attenuation of section near the tunnel is faster than section far from the tunnel if using the Equivalent sound pressure level as the index for evaluation, and the attenuation of the long train(CRH1B) is similar with the short train(CRH1A) on the section near the tunel, which is faster on the section far from the tunnel.