Study On The Vibration Propagation Of High Speed Railway Transportation

With the vigorous development of Chinese high-speed railway industry,the convenience and comfort of people travel between cities has been greatly improved,However,the vibration of high-speed railway train may have a negative impact on the lives of residents along the line.Combined with this background,this paper has carried on the research on the propagation law of high-speed railway vibration based on the subgrade line of Daxing District in Beijing-Shanghai high-speed railway.The main contents can be drawn as follows:(1)On the basis of qualitative discussion on the mechanism of wheel-rail force,the analytical model of vehicle-track system has been established,and the dynamic loads generated by the CRH380 high-speed electric multiple units(EMU)on the CRTS-II slab ballastless track were equivalent to the loads distributed evenly along the surface of the subgrade.The calculation results shown that,when the high-speed EMU is running at 350km/h,the vertical equivalent load of the subgrade surface fluctuates continuously over a wide range.The frequency of the equivalent load was concentrated at two frequency segments: 20 Hz ~ 50 Hz and 65 Hz ~ 90 Hz,and there was a roughly equal cluster frequency concentration.(2)Based on the finite element theory,the harmonic response simulation of high-speed railway subgrade and its surrounding soil was carried out.The result shown that,the vertical vibration amplitude and the vertical vibration acceleration level(VLz)of the ground fluctuate with the increase of the distance,the higher the frequency,the faster the decay.In the low frequency vibration source condition of 5 ~ 35 Hz,the amplitude of the vibration displacement and VLz were linearly attenuated.At higher frequencies,VLz decayed rapidly in the subgrade area and had a certain degree of rebound near the subgrade slope.Afterwards,VLz presented approximately a linear attenuation with the increase of distance.In the range of 30 m away from the vibration source,the impact of high-frequency vibration had been reduced to a lower level,but the low-frequency vibration was still a greater impact.(3)The two-dimensional transient analysis of high-speed railway vibration propagation was carried out when the equivalent vertical loads were used as the loads.The simulation results shown that,the distribution of surface vibration acceleration in the frequency domain was basically the same as that of the vibration source,and the frequency of the acceleration was the most concentrated in the intermediate frequency range of 30 Hz ~ 50 Hz.The vibration acceleration amplitude,VLz and the horizontal distance of the line centerline was negatively correlated.And they were fluctuating attenuation.In the subgrade range,the vibration decayed quickly.Outside the scope of the subgrade,the vibration decay rate tended to be slow.(4)The three-dimensional finite element model of the track-subgrade-soil was established.And three-dimensional simulation of high-speed railway vibration propagation was carried out.The result shown that when the size of the model was 70 m along the vehicle running direction,the three-dimensional simulation results of the vibration index of the subgrade and the surrounding soil were basically the same as the two-dimensional simulation results,and the attenuation of the vibration along the line was not obvious.