Study On Vibration Of Adjacent Building Caused By Subway Elevated Line And Vibration Reduction Measures

In the construction of subway lines network,if the line is adopted with an elevated form and adjacent to the building,the environmental vibration generated by the subway would directly affect neighboring buildings.It is of great significance to study the vibration propagation laws of such adjacent subway lines and adopt effective vibration reduction measures to ensure people's normal activities.In this paper,the vibration propagation law was studied and the environmental vibration evaluation was carried out by combining the engineering case of a subway elevated line in Beijing and its adjacent buildings.Based on this,a variety of vibration reduction measures for the project were discussed.The main research contents are as follows:(1)A vibration test was carried out on the ground which nears the subway elevated line in Beijing and its adjacent buildings.It was found that the half-peak peak value of the vertical vibration acceleration of the ground exceeds twice of the horizontal vibration acceleration,the effective value is also equivalent.The maximum amplitude appeared at the ground floor.The attenuation of vertical vibration in the building is fast at the initial stage and tends to be stable at the later stage.The attenuation rate of the horizontal vibration tends to be slow overall,and there is no section that decays rapidly in a short time.(2)The finite element model was established,the frequency domain and vibration level of the measured data were analyzed while the applicability of the model is verified.The main frequency of vertical vibration on the ground is between 20Hz-120Hz while the peak section is between 50Hz?60Hz.The main frequency of the building which is adjacent to the viaduct is in the range of 20Hz-90Hz while the difference between the floors is small,and the peak appears between 40Hz-60Hz.The maximum Z-magnitude of the ground measurement points near the pier is 76.37dB and 74.92dB which has exceeded the specification limit.The frequency maximum magnitude of vibration of the building appeared in the 2nd basement,1st floor and 3rd floor exceeded the specification limits about 1.82dB,2.28dB and 0.28dB.The vibration increase point appears in the 8th floor of the building,and it was greater than the 5th.(3)The effects of vibration reduction measures of air trenches,filled trenches and single-row piles were discussed through the finite element model.When the depth of the trench is about to the 2nd basement's elevation(9m),about 10%the frequency maximum magnitude of vibration was attenuated.Lightweight aggregate concrete filled trenches at the same depth could attenuate about 6%,both could reduce the vibration over-limit floors.Single-row pile barriers were not as effective as empty trench and filled trench barriers,In the case of 0.6m pile diameter,clear distance between piles was at 1 times pile diameter,the length of the pile needs to exceed the elevation of building base(12m)to reduce the vibration isolation effect.Increasing the clear distance between the piles to 2 times did not effectively reduce the propagation of vibration at this time.