Field Research On Environmental Vibration Measurement And Vibration Isolation Technology Of Beijing-Zhangjiakou High-Speed Railway Subgrade

In recent years,China ’s high-speed railway has developed rapidly.With the deepening of the construction of the main channel of the ’ eight vertical and eight horizontal ’ high-speed railway,the regional connection line of the high-speed railway and the intercity passenger railway,the coverage of the high-speed railway network will be further expanded,and the resulting environmental vibration will inevitably have an adverse impact on the adjacent buildings of the high-speed railway line.Therefore,in order to create a healthy and comfortable residential environment,and to protect the important buildings to meet the urgent requirements of residents to improve the quality of life and the protection of important facilities,it is necessary to carry out the research work of vibration isolation technology of high-speed railway subgrade.In order to effectively solve the negative impact of environmental vibration,this thesis has carried out relevant research on different vibration isolation measures through field measurement,model test and simulation.The main conclusions are as follows:(1)The field measurement test of Fuxing CR400BF-G train in a subgrade section of Beijing-Zhangjiakou high-speed railway in cold area was carried out.The measured data were analyzed,and the propagation and attenuation law of environmental vibration in subgrade section of high-speed railway was mastered.The acceleration amplitude of the time domain curve decreases with the increase of the distance from the outer rail of the line.The dominant frequency of frequency domain curve vibration is distributed in the range of 19Hz～42Hz,and the distribution is concentrated.The vibration level value in the vibration level curve gradually decreases with the increase of the distance from the outer rail of the line.At the same measuring point,the vibration level value in the vibration level curve gradually decreases with the decrease of the vehicle speed.The data processing program is written to realize the batch import,processing and report generation of data,improve the efficiency of data processing,and master the vibration test and data processing technology.(2)Based on the field measured data of Beijing-Zhangjiakou high-speed railway,FLAC3 D is used to establish a three-dimensional dynamic simulation model of high-speed railway subgrade section.From the comparison of the attenuation law of vibration level of subgrade surface environment with distance propagation,it can be seen that the overall vibration level shows a gradual attenuation with the increase of distance from the railway line.The trend and size of the simulation values are in good agreement with the measured values,which further verifies the rationality of the establishment of the simulation model and the selection of parameters,and lays a foundation for the next research on vibration reduction and isolation technology.(3)By constructing a scale test model of different vibration isolation technologies in the indoor model box,the influence of different factors on the vibration isolation effect of the embankment is analyzed.The results show that when the embankment height is less than 15 cm,the vibration isolation effect is better as the embankment height increases.When the embankment slope ratio is less than 1:2,the overall effect of vibration isolation is better with the decrease of embankment slope ratio.(4)The key design parameters of different vibration isolation technologies for high-speed railway subgrade are analyzed by numerical simulation.The three-dimensional dynamic simulation analysis of high-speed railway subgrade is carried out by FLAC3 D for the key design parameters of different vibration isolation technologies.The results show that: For the embankment structure,the embankment slope has better vibration isolation effect when it is upright,so the U-shaped groove structure can be preferred;the foundation reinforcement has obvious vibration isolation effect.The longer the pile length,the better the vibration isolation effect.When the pile diameter is 4m,the vibration isolation effect is better.The pile spacing should be 3 times the pile diameter,and the other pile spacing,even the solid foundation,has no obvious difference in vibration isolation effect.It is suggested that the pile layout with long inner and short outer should be considered in the cross section of embankment,which can effectively reduce the vibration.