地铁车辆段周期性桩基础隔振效果研究

Study on Vibration Isolation Effects of Periodic Pile Foundation Adopted in Metro Depot

针对地铁车辆段及上盖建筑振动控制难题,基于周期结构带隙理论提出周期性桩基础隔振措施,通过开展行车条件下现场测试获得车辆段及上盖平台振动响应,以此为基础建立和校核动力有限元模型,并拓展建立上盖建筑振动计算模型,分析周期性桩基础对上盖建筑的隔振效果。研究发现:(1)实测振动向上盖平台传播分频衰减量约为20 dB~50 dB之间,上盖平台及建筑振动显著频段在25 Hz~50 Hz;(2)上盖建筑部分房间预测值超过限值3 dB~6dB,采用周期性桩基础后可实现设计带隙范围内63 Hz处最大9 dB的分频插入损失以及7 dB的最大Z振级插入损失;(3)周期性桩基础可有效控制上盖建筑10 Hz以下低频振动,最大可降低16 dB。研究成果可为车辆段及上盖建筑振动控制提供一种新的方法和某种地层条件下的具体设计参数。

Aiming at the vibration control problem of metro depot and over-track buildings,the vibration isolation measures of periodic pile foundation is put forward based on the band gap theory of periodic structure.The vibration response of the metro depot and over-track platform is obtained by the site test with trains passing by.On this basis,the dynamic finite element analysis model is established and verified.Furthermore,the dynamic finite element analysis model of metro depot and over-track buildings is established to analyze the vibration isolation effects of the periodic pile foundation.The research results show that:(1)The measured vibration attenuation in frequency propagating from the depot to the overtrack buildings is in the range of 20 dB-50 dB,and the significant vibration frequency band of the cover platform and overtrack buildings is in the range of 25 Hz-50 Hz.(2)The predicted value of some rooms in the over-track buildings exceeds the limit value by 3 dB-6 dB.With the periodic pile foundation adopted,the VLmax insertion loss of 9 dB at 63 Hz and the VLzmax insertion loss of 7 dB within the design band gap can be achieved.(3)Using periodic pile foundation can effectively control the low-frequency vibration below 10 Hz of the over-track structure and attain the maximum attenuation value of 16 dB.The research results of this paper may provide a new method and specific design parameters for the vibration control of the metro depot and over-track buildings.