列车运行时由轨道不平顺引起的地基振动研究

采用半解析法研究了列车荷载作用下列车-轨道-饱和地基系统的耦合振动问题。研究模型共分为3部分：车体简化为一个多刚体系统，在车轮与钢轨之间引入线性Hertizian弹簧接触模型模拟轮轨动力相互作用、采用离散轨枕支撑的弹性Euler梁来模拟轨道系统、下卧土体采用多孔饱和半空间模型。列车荷载分为轴重和由轨道不平顺引起的轮轨动力相互作用力。采用Fourier变换分别求解各子系统的控制方程，并通过动力子结构法对各子系统进行耦合。土体在时域内的动力响应通过快速Fourier变换求得。在分析了轮轨动力相互作用力的基础上，研究了轮轨动力作用力和列车轴重作用下饱和地基的动力响应，并分析了轨枕间距和土体渗透系数对饱和地基振动响应的影响。研究表明，轮轨动力作用力对地基远场振动有重要贡献，同时枕木间距对轨道与地基振动响应有较大影响。

Study of ground vibration from trains caused by track irregularities

The vibrations of vehicle-track-saturated ground coupling system subjected to moving train loads are investigated by a semi-analytical approach.The theoretical model is divided into three components: the vehicle is described as a multi-rigid-body system,and a linear Hertizian contact spring between each wheel and the rail is used to simulate the dynamic wheel-rail interaction forces;a periodically supported Euler beam is introduced to simulate the track system;a fully saturated poroelastic half-space is used to simulate the ground and governed by Biot’s theory.Train loads include two parts: the axle loads and the dynamic wheel-rail loads assumed to be generated from the track irregularity.The governing equations of each component are solved by using Fourier transform,and these components of the whole system are integrated to meet the displacement compatibility and force equilibrium by the substructure method.The time domain responses of the ground are obtained through the fast Fourier transform.On the basis of the analysis of the dynamic wheel-rail loads,the dynamic responses of the ground subjected to the axle loads and the dynamic wheel-rail loads are investigated.Influences of the sleeper span and the soil intrinsic permeability on the soil dynamic responses are also analyzed.It is concluded that the dynamic wheel-rail load has important contribution to the far-field ground vibrations,and also the sleeper span has obvious influence on the track and ground vibrations.