运行列车引起地面振动的理论模型及振动特性分析

根据车辆动力学、轨道动力学及地基土振动Green函数,建立了列车-轨道-地基土相互作用理论分析模型.该模型不仅考虑了车辆自身的振动,而且考虑了由轴重荷载组成的准静态激励力和单一波长轨道不平顺引起的轮轨问动态激励力.列车模型、轨道模型和地基土模型之间分别通过轮对-钢轨之间的Hertz接触和轨枕-地基土的动力平衡关系进行耦合.根据该模型通过-算例对地面的振动特性进行了分析,并通过移动的单位常力荷载和单位简谐荷载作用下的地面振动分析了车速和地基土特性的影响.计算结果表明,运行列车引起的地面振动特性与荷载移动速度和地基土特性紧密相关,列车移动速度线和地基土频散曲线的相交频率是引起地面振动放大的一种共振频率;运行列车存在临界速度,且临界速度接近地基土模型中的最小表面波波速;轮轨接触表面不平顺引起的动激励力振源对地面振动的高频成分产生较大的影响.

Theoretical model and characteristic analysis of moving train induced ground vibration

Based on the vehicle dynamics, track dynamics and the Green's functions of foundation soil, an integrated train-track-soil dynamic interaction model is established, which can be used to predict the train-induced free-field vibrations. In the model, the vibrations of vehicle components, the quasi-static axle loads and the dynamic excitations caused by track irregularity that is simulated by the single wavelength harmonic profile herein, are all taken into account. The models of train, track and soil are coupled through dynamic wheel-rail Hertz contact and the dynamic equilibrium relationship of sleeper-foundation soil, respectively. Using the theoretical model, the ground vibration characteristics are analyzed through an example, and furthermore the influences of train speeds and soil properties on ground vibrations are analyzed by the moving unit constant load and unit harmonic load. The calculated results show that the characteristics of ground vibrations have a close relationship with train speeds and soil properties; the intersection frequencies of velocity lines of moving train and dispersion curves of subsoil are some resonance frequencies which induce the amplification of ground vibration; there exists a critical speed for moving train which is close to the minimum speed of the Rayleigh wave in the subsoil; the dynamic excitation produced by wheel-track irregularity has great influence on high frequency components of ground vibration.