DYNAMIC RESPONSES OF TRACK SYSTEM AND SATURATED SOIL IN HALF SPACE SUBJECTED TO A MOVING TRAIN LOAD
移动列车荷载作用下路轨系统及饱和半空间土体动力响应

The dynamic responses of track system and saturated soil in half space subjected to a moving train load are investigated analytically. The system is divided into two parts,the track and the ground. The track system consists of three parts:rail,sleepers and ballast. The rail is modeled by introducing the Green function for an infinitely long Euler beam subjected to the action of the moving train load and the reaction of sleepers. The sleepers are represented by the continuous masses. The effect of the ballast is considered by introducing the Cosserat model. Neglecting the gravity of the soil medium,the Biot theory of a fully saturated poroelastic half-space is employed. By making use of the double Fourier transform,the governing equations of motion are solved in the frequency-wave-number domain. The governing equations of the soil medium and the track system are coupled by the boundary condition on the surface of the ground. The time domain responses are evaluated by the inverse Fourier transform computation for the cases that train velocity is lower or higher than soil Rayleigh-wave velocity .Computed results show that the dynamic responses of soil medium and rail are considerably affected by the fluid phase as well as train velocity. At low train velocity,whether the soil is considered as poroelastic medium or elastic medium only influences the amplitude of the soil and rail displacement. However,the responses for poroelastic medium are quite different from those for elastic medium when the train velocity exceeds Rayleigh-wave velocity of the soil medium.