| High speed railway is an important transportation infrastructure in the world.By the end of 2019,China’s high-speed railway has run more than 35000 kilometers,ranking first in the world.The following environmental vibration problems are increasingly prominent.The environmental vibration caused by high-speed railway has an important impact on the safety of surrounding buildings,the normal use of nearby precision instruments and the physical and mental health of residents along the line Impact.In this regard,experts at home and abroad have carried out in-depth research,especially in the soft soil area for a large number of field measurements and theoretical analysis,but for the loess area of China,the study of environmental vibration of high-speed railway is less.Therefore,under the background of large-scale construction of high-speed railway in loess area,strong vibration damage and few related research,it is of great theoretical significance and engineering value to study the environmental vibration characteristics,propagation rules and vibration reduction and isolation problems caused by high-speed railway in typical loess area.This paper takes "Datong Xi’an high speed railway" in typical loess area as the research object.Firstly,by collecting relevant documents and investigation data,we get the basic characteristics and physical and mechanical parameters of loess along the line of Datong Xi’an high speed railway,which not only provides the material parameters for the soil characteristics of Loess,but also for the numerical simulation.Then,according to the form of high-speed railway subgrade,we divide the embankment In the five working conditions of road cutting,bridge,culvert and ground crack crossing site,low-frequency vibration sensors are respectively arranged under each working condition to measure the vertical speed of ground vibration caused by high-speed train operation on site.The vibration characteristics under different working conditions are analyzed from the aspects of time domain,frequency domain,vibration propagation law and environmental vibration evaluation,and their differences are compared.Finally,Midas GTS is used to analyze the vibration characteristics under different working conditions Nx finite element software is used for numerical simulation and comparative study with the measured results.The vibration prediction and vibration isolation suggestions under different working conditions are proposed.The results show that the ground vibration caused by high-speed railway is periodic excitation,and there is superposition effect at the bogie;the peak value of vertical vibration acceleration decreases with the increase of distance from the track center line,generally in the range of 0-15 m,the deceleration rate is large,and the attenuation is slow after 15 m,and the attenuation process is affected by wave reflection,interference,surface Rayleigh and scattering of track parts,etc In general,the ground vibration of the cutting condition is greater than that of the embankment condition,and the embankment condition is greater than that of the culvert condition and the bridge condition.The peak value of acceleration tends to rise with the increase of the train speed,but the further away from the track center line,the greater the impact The main frequency range of railway vibration is generally between 5-80 hz,far away from the track,and its main frequency is concentrated around 5-20 hz.The attenuation effect of high-frequency section is obvious,and the attenuation of low-frequency section is relatively slow.The environmental vibration of some areas along the railway exceeds the vibration limit of "residential area" and "commercial area";the dynamic characteristics of the foundation under the ground fissure site condition are obvious "upper and lower plate" At the same time,the results of this paper have certain reference value for the prediction of ground vibration and vibration reduction and isolation of high-speed railway in loess area. |
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