基于地铁列车运行引起的振动预测模型的浮置板轨道减振效果研究

针对地铁列车运行引起的隧道及土层振动响应问题提出数值预测模型。该模型根据移动荷载作用下动力响应解,将地铁列车运行引起的振动问题归结为计算频率-波数域内传递函数和频域内移动轴荷载问题。传递函数采用三维周期性有限元-边界元耦合模型计算,移动轴荷载主要考虑为频域内轨道不平顺激励下轮轨接触力。利用上述模型计算北京地铁4号线北京大学东门站北侧区间地铁列车运行引起的振动响应,并结合现场振动实测数据探讨该区间浮置板轨道减振效果。结果表明:模型具有良好适用性,可应用于地铁列车运行引起的振动预测;浮置板轨道是一种有效减振措施,在其工作频段内有明显减振效果,但在低频,浮置板轨道不能起到减振作用。

Study on Isolation Efficiency of Floating Slab Track Using a Numerical Prediction Model of Metro Traffic Induced Vibrations

A numerical model was presented to predict the vibrations in the tunnel and soil strata induced by passage of Metro trains.In this model,based on the analytical solution of dynamic responses excited by moving loads,the vibrations induced by passage of Metro trains can be calculated if the transfer function in the frequency-wavenumber domain and the moving axle loads in the frequency domain can be obtained.The transfer function was calculated using the three-dimensional coupled periodic finite element-boundary element model in the frequency-wavenumber domain,and the moving axle loads were considered as the contact forces between wheel and rail due to rail unevenness in the frequency domain.The dynamic responses in the section north of the East Gate of Peking University Station of Beijing Metro Line 4 were calculated using the model,and then the isolation efficiency of the floating slab tracks in the section was studied by means of the in-situ vibration experiment and the numerical calculation.The results show as follows: The model has good applicability and can be used to predict the vibrations induced by Metro traffic;laying of floating slab tracks is an effective vibration isolation measure;floating slab tracks can efficiently reduce vibrations in their work frequency range,however,they cannot mitigate vibrations at low frequencies.