Analysis Of Ground Vibration Generated By Trains On Layered And Saturated Layered Ground

With the railway development, especially for high-speed train, the ground-borne vibration due to railway traffic has an increasing effect on precision instruments, equipment, buildings and the living environment of human beings as well. On the other hand, the increasing improvement of living standard makes the requirement to the environment of living and working more strictly than before. As a result, the project on the ground-borne vibration due to railway traffic is becoming a special concern in the civil and environmental engineering field. In this paper, the propagation and attenuation of the ground vibration due to high-speed train are studied. The main contents of the paper are as follows.The force between the sleeper and the ground is derived from the deflection curved of track, modeled as a beam on an elastic foundation. The basic solution of layered half space is obtained by the TLM (Thin Layer Method) using the second shape function and the vibration model of moving train-track-ground is constructed. The vibration amplitudes of the ground in the frequency domain can be calculated. By using IFFT, the vibration amplitudes in frequency domain are translated into time domain. The effects on the ground vibration by the factors such as the length, the load and the speed of the train are analyzed. The results indicated that the acceleration spectrum has a maximum at the fundamental axle passage frequency; the acceleration has a rather weak dependence on train speed when the speed below the Ralyeigh wave velocity of the upper layer, while a vibration boom may be expected when the train speed reaches this Ralyeigh wave velocity. A common character is that vibration generated by traveling trains attenuates much quickly in the near distance and decreases slowly in the far distance. The ground vibration is effected largely by the load of the axis and less by the train length.Based on Biot's dynamic equation, the TLM is adopted to derive the solution of Lamb's problem for layered saturated foundation under the action of dynamic load. The displacement expression in the frequency-wave number domain for layered...