移动简谐荷载下浮置板轨道-隧道-地基模型二维振动响应研究
2D Dynamic Response of Floating Slab Track-Tunnel-Ground Model Under Moving Harmonic Load
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摘要: 为分析地铁隧道中浮置板轨道的减振特性,基于轨道-隧道-地基二维耦合模型,通过引入位移势函数和双重傅里叶变换,推导了移动简谐荷载作用下二维耦合模型的位移响应解答,研究了浮置板轨道参数敏感性.研究表明,二维耦合模型存在3个自振频率,地层的位移响应以低频为主,峰值频率在1Hz左右,不同荷载频率下地层竖向位移沿深度的变化规律不同.地层加速度响应以中低频为主,第二自振频率对应的地层加速度峰值最大,采用浮置板轨道并不能减少地层振动位移,但可以有效降低1.414倍第二自振频率以上地层振动的加速度响应.增加浮置板质量和降低钢弹簧刚度可以减少地层的加速度响应达到减振目的,改变钢轨扣件刚度和浮置板抗弯刚度对地层加速度响应的影响很小.研究可为地铁环境振动的快速评估提供参考.Abstract: A two-dimensional (2D) floating slab track-tunnel-ground coupled model was adopted to analyze the vibration characteristics of floating slab track in the metro tunnel.By introducing displacement potential functions and using double Fourier transformations,response solution of the 2D model under moving harmonic load was derived.It indicates that there are three resonant frequencies in the 2D model,the ground displacement response mainly concentrates in the low frequencies,with a peak value frequency around 1Hz,and the changes of vertical ground displacement under different load frequencies are different.The ground acceleration response mainly concentrates in the middle and low frequencies and reaches its maximum value at the second resonant frequency.Adopting the floating slab track is unable to reduce the ground displacement but is effective to reduce the ground acceleration response in which the load frequency is above 1.414 times of the second resonant frequency.Increasing the floating slab mass and decreasing the steel spring stiffness are able to reduce the ground acceleration response and realize the vibration attenuation goal while the ground acceleration is trivially affected by changing stiffness of the rail pad or floating slab.The present research can provide reference to a quick evaluation for the train-induced environmental vibration.