| At present,the major cities in China are vigorously developing the property on the subway to alleviate the shortage of urban land and traffic jams.Due to the uneven track and wheel loss of metro train,the vibration generated by train operation spreads to the surrounding soil and surface buildings through the metro station.Because of the particularity of the structure of the subway station,the train vibration will be directly transmitted to the building through the station structure.Due to the lack of corresponding vibration control measures,it is bound to affect the life and work of vibration sensitive people,resulting in the decline of precision equipment.Therefore,it is necessary to study the influence of subway train vibration on the properties of subway station.In this paper,taking Guangzhou Foshan financial high tech metro station project as the research object,the dynamic response characteristics of the metro station under the soft combination of the upper cover property are deeply studied by using the methods of model test,field measurement and numerical simulation:（1）Based on the investigation of domestic and foreign cases,the combination mode of metro station superstructure property is divided into soft and hard combination mode.Among them,"soft combination" is defined as that the properties on the subway station are not directly connected,and there are rock and soil between them The form of "hard combination" is defined as the direct connection between the properties on the subway station or the connection between the two through the column network.（2）Through monitoring the vibration acceleration of ballasted track and ballastless track in the track area of Guangzhou metro station,it is found that the vibration frequency response caused by train operation mainly ranges from 30 Hz to250 Hz,and the peak frequency is 70 Hz.The vibration caused by the acceleration of train leaving the station is greater than that caused by the deceleration of train entering the station,And the vibration intensity caused by the empty train passing through the station is the same as that caused by the acceleration of the train leaving the station.（3）The dynamic response of train vibration to different interlayer thickness of metro station’s superstructure with soft joint is studied by constructing similar test.Under the action of 0～200Hz sweep frequency load,the frequency response range of superstructure is60～200Hz,the vibration acceleration decreases from the vibration source position to the far end in the transverse direction,and increases first and then decreases in the vertical direction,That is to say,there is a vibration amplification area in the middle floor of the upper property.The thicker the thickness of the soft bond interlayer,the stronger the vibration acceleration and Fourier spectrum amplitude reduction of the upper cover property,especially for the amplitude above 100 Hz,which shows that the soft bond has a significant weakening effect on the train vibration intensity and high frequency components.（4）Based on the coupling model of train and rail,the fastener force under different speed of train is simulated considering the track irregularity.The same numerical simulation model is established by using the finite difference numerical simulation method,the acceleration response of the upper cover property is calculated by applying the same boundary and load,and the mutual check with the test results is carried out,which proves the correctness of the boundary conditions and damping.（5）Based on the verified numerical simulation method and relying on the financial high tech metro station project,a three-dimensional finite difference model of Metro soft composite sandwich roof property is established.The vibration acceleration,Fourier spectrum and 1/3octave band vibration level are selected as the dynamic response analysis indexes,and the data are compared with the field measured vibration acceleration of metro station hall,The correctness of the numerical simulation model is verified,and the dynamic response characteristics of the upper cover property under the changes of train speed,thickness and stiffness of the soft interlayer are studied:1)The faster the train running speed is,the greater the vibration acceleration,Fourier spectrum amplitude and vibration acceleration level of each floor of the upper cover property are.When the train speed reaches 80 km / h,the acceleration level of the upper cover property exceeds the standard limit of vibration level.The frequency response range of the upper property is non monotonic with the increase of vehicle speed.When the vehicle speed is40km/h or 80km/h,the frequency response range of the upper property is 40～100Hz,and when the vehicle speed is 60km/h,the frequency response range is 40～140Hz.2)The smaller the stiffness of the soft interlayer,the weaker the vibration acceleration,Fourier spectrum amplitude and vibration acceleration level of the upper cover property.It shows that the soft interlayer has a good damping effect on the vibration of the upper cover property.But for the attenuation rate of the train vibration passing through the soft interlayer to the first floor of the upper cover property,the attenuation rate of the interlayer with higher stiffness is higher.When the interlayer is soft soil,the frequency response range is 40～100Hz,and the frequency response range of hard rock interlayer is 40～180Hz;3)The effect of soft soil thickness on vibration acceleration is not linear.With the increase of interlayer thickness from 0.5m to 2m,the peak value of vibration acceleration of the roof property first decreases and then increases.The interlayer thickness with the best weakening effect on train vibration is 1.5m.With the increase of soil thickness,the vibration frequency response range of the superstructure decreases from 40～180Hz to 20～60Hz.It can be seen that the vibration frequency attenuation of the train is mainly completed in the soil interlayer,and the increase of soil thickness significantly weakens the high frequency of vibration. |
PDF Full Text Request