Study On Train-induced Vibration Propagation Characteristics And Vibration Isolation Effect Of Utility Tunnel In Metro Depot

In recent years,the scale of domestic urban rail transit construction is huge,the metro depot matched with the subway occupies a lot of construction land,the new subway depot is generally planned to have the development of the over-track buildings,and the vibration caused by the operation of the subway train in the depot has attracted widespread attention.Some researchers have carried out vibration tests in the metro depot,but the trains are mainly A-type andB-type.There is little research on the vibration caused by the L-type car in the depot.There are many and miscellaneous pipelines in the metro depot,and utility tunnel has been used in some metro depot,but the research on the vibration isolation effect of the utility tunnel has not been reported.Vibration tests were carried out in Luogang metro depot of Guangzhou Metro Line 6,which use L-type cars.The test sections are located near the test line and throat area,the cover plate of the throat area,the over-track building near throat area,respectively.The vibration caused by the operation of L-type cars in the test line and throat area is analyzed from the point of view of peak vibration acceleration,vibration frequency characteristics and vibration acceleration level.The vibration response law of the cover plate and the over-track building is studied.The finite element model is established by ABAQUS.The vibration isolation effect of the utility tunnel is studied by the method of numerical simulation,and the influence of the position and shape of the utility tunnel on the vibration isolation effect is analyzed.The main conclusions are as follows:(1)The vibration caused by L-type car running on the test line is mainly in vertical direction.On the ground 7m away from the center line of the track,the peak vertical vibration acceleration can reach 0.83m/s~2,the vibration frequency is concentrated at 45～60Hz.The vertical vibration is greater when the train through switch reversely.(2)The vibration caused by the L-type car running on the straight track in the throat area is mainly in vertical direction.On the ground 5.8 m away from the center line of the track,the peak vertical vibration acceleration can reach 0.46m/s~2,the vibration frequency is concentrated in 30～35Hz and 55～75Hz.(3)The average vibration of the platform in the throat area is 65～73dB,which cannot meet the requirements of comfort.The cover plate is suitable to be used as a parking lot or sports field.The maximum vertical vibration of the cover plate is in the middle of the frame beam span,and the maximum horizontal vibration is at the edge of the column.(4)For the 9-story building with large chassis and single tower frame structure with pile foundation,the tower structure is about 30m away from the track of the throat area,and the vibration of each floor in the building is less than 60dB,which meets the requirements of comfort.The changing law of the vibration level is similar to that of the second order vibration mode.By analyzing the characteristics of the vibration mode of the structure,the floor with the largest vibration can be determined.According to the measured vibration level of one floor measuring point,the vibration level of other floors can be predicted.(5)The utility tunnel can have a good vibration isolation effect when the buried depth is1.2m,the damping effects on the vibration of 70Hz,50Hz and 30Hz are 5.5dB,4.7dB and 0.5dB respectively.It is suggested that the utility tunnel should be buried shallowly as far as possible on the premise of meeting the application requirements.