ANALYSIS OF GROUND VIBRATION INDUCED BY TRAIN MOVING LOADS

This paper presents a 2.5 dimensional (2.5D) finite element method (FEM) to study the three-dimensional (3D) dynamic responses of track structure and surrounding ground under high-speed train's quasi-static multi-wheel axle loads and harmonic loads. The track and the attached sleepers are simplified as Euler beams resting on infinite half-space, and that the ground with complicated geometries and physical properties is modeled by FE-M. The wave-number transform in the load moving direction is applied to reduce the 3D dynamic problem to a two-dimensional (2D) problem, in which each node has three degrees of freedom. The dynamic problem is solved in a section perpendicular to track direction, and the 3D responses of the track and the ground are obtained from the inverse wave-number expansion. The results show that the vibration induced by multi-wheel axle train loading is much more complicated than single load. The track and the ground have a strong vibration when the speed of train is closed to the shear wave speed of the ground, but the vibration amplitudes decrease gradually with further improvement of the train speed. The acceleration amplitudes induced by train moving harmonic loads are about three times of quasi-static loads and vertical displacement amplitudes are almost identical near the track. Vibration induced by harmonic loads decay slowly and has some rebound away from the track center.