【作者】 丁德云；

【导师】 刘维宁；

【作者基本信息】 北京交通大学 ， 桥梁与隧道工程， 2010， 博士

【摘要】 近年来,地铁运营引起的环境振动问题越来越受到人们的关注,尤其是低频(＜20 Hz)振动对高精密仪器、设备等的影响。地铁列车引发的潜在环境低频振动的传播有何特征,有待于研究。如何采取合理的减振措施,将低频振动的影响减到最小,是亟需解决的问题。本文主要研究在钢弹簧浮置板轨道和普通轨道型式下,低频振动的传播特征以及关键参数对环境响应低频特征的影响。采用实验室试验、理论和数值相结合的方法,从“轨道-隧道-地层”系统整体考虑,建立了针对低频振动的分析模型,推导了地表低频振动的分析公式,并对影响地表低频振动的一些关键参数进行了评价。1、利用北京交通大学轨道减振与振动控制实验室开展钢弹簧浮置板轨道和普通轨道低频振动测试,来研究:(a)低频振动在隧道内的传播衰减规律;(b)低频振动在地表中的传播衰减规律;(c)低频振动在邻近建筑内的传播衰减规律;(d)钢弹簧浮置板轨道的弹簧刚度和支承间距等关键技术参数变化对低频振动的影响;(e)比较普通轨道和钢弹簧浮置板轨道的低频减振效果。2、采用模态分析的方法,对试验中的钢弹簧浮置板轨道和普通轨道进行了全面的动力特性研究;基于正交试验的理论,对浮置板轨道进行了详细的参数研究,分析了浮置板轨道的道床板长度和厚度、弹簧刚度、支承间距、扣件刚度等参数是如何影响浮置板轨道的动力特性:分析比较了不同轨道体系的传导比。3、基于试验数据,利用有限元法,分别建立了“浮置板轨道-隧道-地层”和“普通轨道-隧道-地层”耦合系统的三维数值分析模型,拓展研究一般情况下地表的低频振动量、插入损失以及传递函数。4、利用实测数据和数值模拟结果,采用回归分析的方法,研究了浮置板轨道和普通轨道下地表低频振动受激振频率(1～20 Hz)、距轨道水平距离(0～100 m)和隧道埋深(10～30 m)等的影响,推导出地表低频振动量分析公式。5、基于公式预测的地表低频响应量,将其最大值分成Ⅰ、Ⅱ、Ⅲ、Ⅳ四级响应带,并讨论了响应带分布与隧道埋深、距轨道水平距离和轨道基频等关键参数的关系。更多还原

【Abstract】 In recent years, environmental vibrations induced by metro trains have been paid more and more attention; especially the low frequency (<20 Hz) vibrations might affect the operation of sensitive equipment and high-tech machinery. It is necessary to further study the characteristics of the propagation of potential environmental low frequency vibrations due to metro trains. How to adopt reasonable vibration mitigation measures to minimize the impact of low frequency vibrations is an urgent problem to be solved.Based on the steel spring floating slab track (FST) and the ordinary track (direct fixation fasteners) in the tunnel, the characteristics of the propagation of low frequency vibrations have been studied, as well as the influence of key parameters on the low frequency characteristics of environmental vibrations. Using the combination of laboratory test, theoretical analysis and numerical method, the coupled track-tunnel-soil system is modelled to analyze the low frequency vibrations. The analysis formula of low frequency ground vibrations is derived. The critical parameters and their influence on low frequency ground vibrations are evaluated.Low frequency vibration tests on the steel spring floating slab track (FST) and the ordinary track in the Laboratory of Track Vibration Abatement and Control on the campus of Beijing Jiaotong University are carried out to study: (a) the attenuation of low frequency vibrations in the tunnel; (b) the variation of low frequency vibrations in the free field; (c) the response of low frequency vibrations in an adjacent building; (d) the influence of varied key parameters including the stiffness and spacing of steel springs; (e) the comparison of vibration isolation efficiency between the FST and the ordinary track.Dynamic characteristics of the FST and the ordinary track are studied in detail, using the modal analysis method. Based on the theory of orthogonal experimental design, a detailed parametric study is performed to analyze the influence of various parameters on the dynamic characteristics of the FST. The parameters are related to the length and thickness of the slab, the stiffness and spacing of the slab bearings and the stiffness of the rail pads. The transmission ratios of different tracks are obtained and compared.Based on measurement data, the coupled FST-tunnel-soil system and the coupled ordinary-track-tunnel-soil system are respectively modelled by using the finite element method to further analyze the vibration level, insertion loss and transfer function of low frequency vibrations.On a basis of test data and numerical results, the influence of the excitation frequency (1-20 Hz), the distance (0-100 m) from the track and the buried depth (10-30 m) of the tunnel on the low frequency ground vibrations are analyzed, using the theory of regression analysis. Hence, the analysis formula of low frequency ground vibrations is derived.Maximum values of vibration acceleration level calculated from the analysis formula are divided into four-level response zones consisting of I, II, III and IV. The relationship between the distribution of response zones and critical parameters including the buried depth of the tunnel, the distance from the track and the basic frequency of the track is elaborated.更多还原