高速列车荷载作用下路轨系统及饱和地基的动力响应

将在高速移动列车荷载作用下的铁路系统分为上覆路轨系统和下卧土体两部分.对于下卧土体部分,通过Fourier变换求解Biot多孔饱和介质的动力方程.对于路轨系统,将钢轨简化为无限长弹性Euler梁,将枕木简化为连续质量块,同时考虑道渣层的影响.用一系列符合列车几何尺寸的点荷载来模拟列车荷载.在Fourier变换域内,联立路轨系统和下卧土体的动力方程,求解在列车荷载作用下的钢轨位移和加速度、土体位移和加速度及土体孔压的表达式.利用数值积分方法对表达式进行Fourier逆变换,得到钢轨位移和加速度、土体孔压在时域内的表达式.通过算例讨论了荷载移动速度和土体渗透系数对钢轨速度和加速度及土体孔压的影响.结果表明,水相介质的存在和荷载移动速度均对土体动力响应产生很大影响.

Dynamic responses of track system and poroelastic soil under high-speed train load

The vibration of a rail track system on fully saturated poroelastic half-space soil subjected to a moving train load was investigated.The system was divided into two parts,track and ground.The ground was modeled by introducing Biot theory for the fully saturated poroelastic medium.By using the Fourier transformation,the governing equations of the ground were solved.On top of the ground,the ballast was placed,supporting the rails and the sleepers.The rails were modeled as Euler beams,and the sleepers were represented by a mass.The train load was simulated by a series of moving point load in accord with the geometry of a real train.The governing equations of the ground and the rail system were then coupled in the frequency-wave-number domain,and the expressions of displacement and acceleration of the rail and soil as well as the pore water pressure of the ground were calculated.Then their expressions in time domain were evaluated by the inverse Fourier transform computation for a certain load velocities.Computed results showed that the dynamic responses of the soil medium are considerably affected by the fluid phase as well as the load velocity.