GROUND VIBRATIONS DUE TO UNDERGROUND TRAINS BY THE 2.5D FINITE/INFINITE ELEMENT APPROACH

The 2.5D finite/infinite element approach is adopted to Study the wave propagation problems caused by underground moving trains. The irregularity of the near field, including the tunnel and parts of the soil, can be easily simulated by the finite elements, and the wave propagation properties of the far Field extending to infinity can be modeled by the infinite elements. Moreover, the 2.5D approach enables US to Compute the three-dimensional response of the half-space, with the load-moving effect taken into account, using only a two-dimensional profile. Although the 2.5D finite/infinite element approach shows a great advantage in studying the wave propagation problems caused by moving trains, attention should be paid to the calculation aspects, such as the rules for mesh establishment, in order to prevent this method from being used erroneously. In this paper, some essential points for consideration in analysis will be pointed out, along with the techniques for enhancing the calculations. All these should prove useful to make the 2.5D finite/infinite element approach an effective one.