Vibration Characteristics And Prediction Analysis Of Sunken Depot And Upper Building Caused By Train Operation

The subway is one of the important means of transportation in the city.Because of its advantages such as fast,convenient,large capacity,high efficiency and not affected by traffic factors,it is well received by people.Important role.As a new type of subway car depot,the sunken car depot means that the main structure of the car depot,such as a parking lot,a car depot,is built underground,without occupying the upper ground space.Compared with the typical underground subway depot,the vibration problem of the sunken depot is particularly prominent,which affects the working performance of the building.This article focuses on the environmental vibration problems caused by sunken depots,systematically studies its vibration characteristics and propagation laws through field measurement methods,and establishes a refined dynamic analysis model to transfer train vibration in the new structure of sunken depots.The research and analysis are carried out,and the vibration of the superstructure is predicted and evaluated,which will provide guidance for the vibration prediction,comfort evaluation and vibration reduction of sunken vehicle sections in the future.The main research is as follows:(1)According to the train return and departure time of the depot,a comparative analysis is performed to determine the evaluation criteria suitable for this article.Firstly,the Z-level is evaluated by using the nighttime standards of Type 2 mixed areas and commercial central areas in JGJ / T 170-2009 "Limits and Measurements of Building Vibration and Secondary Radiation Noise Caused by Urban Rail Transit".Then,according to GB / T 50355-2018 "Limits of Residential Building Indoor Vibration Limits and Measurement Methods Standard" at night,the vibration of the cover plate is evaluated.(2)On-site measurement of the inside line of the sunken depot and the throat area(non-fork area),and analysis of vibration source characteristics and comfort analysis at different positions of the vehicle depot.The measured data show that the rail response of the rail inside the library is greater than that of the minus two.The peak value of the horizontal vibration acceleration of the rail in the throat area(non-fork area)is significantly larger than that in the library line.The vertical acceleration in the plate span caused by the train operation is the largest,and it is most reasonable to use the vertical vibration response in the plate span as the comfort evaluation.(3)Establish a track-sunken depot-land finite element model.The boundary conditions and damping parameters of the model were determined,the load simulation method and loading method were given,and the vibration acceleration at the cover plate in the model was extracted and compared with the actual measurement to verify the feasibility of the model.(4)The finite element model is used to simulate the train operating conditions,and the conclusions are as follows: The vibration energy of the measuring points on the cover plate is concentrated at 5-50 Hz,and the frequency decreases with the increase of the distance from the train to the track;When the layers pass,the vibration acceleration level at the cover is greater than the negative two layers in the full frequency band area.When the negative second floor passes,compared with the negative second floor,the cover plate and the negative one,the vibration attenuation is obvious in the range of 12.5 ? 100 Hz.There is a big difference between the lateral vibration transmission and the interlayer vibration attenuation of the sunken vehicle section.(5)Evaluation of the comfort and vibration energy of the sunken depot,and the following conclusions are drawn: When the negative layer passes,the cover plate measuring point exceeds the limit in the frequency band of 5?8Hz,and is within 40 m from the train passing track.The inside exceeds the requirements of the specification;when the negative second floor passes,the cover is 7m away from the train running track and meets the requirements of the specification.As the distance from the passing track of the train increases,the Z level on the cover plate decreases,and the Z level at the pillar is greater than the nearby area.The Z vibration level in the longitudinal section shows a radiation attenuation trend to the surroundings,and the attenuation to the lower part of the vehicle section is significantly faster than the upper part.In the range of 12.5?200Hz,the vibration acceleration level of the upper pillar is obviously greater than that of the lower pillar.(6)Taking into account the vibration reduction analysis of the negative train of the sunken depot through the vibration exceeding the standard,the following conclusions are obtained: in the inner line section of the sunken depot,the running speed of the train is reduced and the vibration reduction using the damping fasteners The effect of the vibration measures was not satisfactory,and the expected goals were not achieved.(7)The finite element model of ground-sinking depot-top building was established to predict and analyze the vibration of the top building caused by train operation,and the following conclusions were reached: In the case of no vibration isolation,with the increase of floors,The acceleration peak value keeps decreasing.When reaching a certain height,the floor vibration response is basically consistent in the time domain,and the vibration acceleration peak value changes little.During the transmission of vibration from the bottom to the top of the building,the high-frequency vibration attenuation of 10 to 40 Hz is obvious,and the low-frequency vibration attenuation of the 0 to 10 Hz range is small.The vibration isolation efficiency of the base vibration isolation support is related to the vertical stiffness of the support.The smaller the stiffness,the better the vibration isolation effect.After the stiffness is increased to a certain value,the vibration isolation performance will be lost.When the vibration isolation layer effectively reduces the vibration response of various frequency bands,the attenuation of low-frequency vibration will decrease,which will cause the phenomenon of low-frequency vibration amplification in the high-rise building.It is the lowest point of the Z level at the height of 3/5 of the building.