移动荷载作用下轨道路基动力响应分析

基于层状梁和粘弹性半空间体理论建立轨道路基耦合动力分析模型;通过移动坐标和Fourier变换得到移动谐振点荷载作用下轨道路基稳态响应在波数域内的解;再利用快速Fourier逆变换,求出钢轨、轨枕位移及道碴路基的相互作用力在空间域内解。通过算例分析荷载速度对路基表面位移的影响,结果表明:随荷载速度增大,路基表面位移峰值也增大,在荷载速度较低范围内,其对路基位移峰值影响不大,当荷载速度接近Rayleigh波速时,路基位移峰值急剧增大;随着荷载速度的增大,路基竖向位移分布呈现出的“波动性”也越来越明显,其“波长”随荷载速度的增大而减小。

Study on the Dynamic Response of the Track/Subgrade under Moving Load

Based on the theory of layered beam and viscoelastic semi-infinite solid,a coupled dynamic analysis model of track/subgrade is developed.By means of moving coordinate and Fourier Transform,the steady state dynamic response of the track/subgrade system under moving harmonic point load is obtained in the wavenumber domain.The rail,sleeper displacement and the interaction force between ballast and subgrade in space domain are obtained by using the Fast Fourier Transform.Numerical examples are provided to examine the influence of load velocity on the subgrade displacement.Results show that the peak amplitudes of subgrade vertical displacement increase with the load velocity.In low-speed scope,the load velocity has slight effect on subgrade displacement.When the load velocity is close to the Rayleigh wave speed of the subgrade,the maximum subgrade displacements have a significant increase.The vertical displacement distribution of the subgrade exhibits apparent oscillations and the wavelength decreases as the load velocity increases.