In order to investigate the ground vibration induced by the operation of high-speed trains during earthquakes

a seismic load input formula in the frequency domain was derived based on the equivalent load method

and the equivalent linearization method was adopted to describe the nonlinear response of soil. On the basis of the two-and-a-half-dimensional finite element method (2.5D FEM) of ground vibration under high-speed train load

a 2.5D finite element model of nonlinear layered ground under combined seismic and high-speed train loads was established. The effects of vehicle speed and soil stiffness on the layered ground vibration under combined loads were analyzed. Results showed that the ground vibration displacement at the center of the track caused by seismic and high-speed train loads increased with the increase in vehicle speed

and it decreased with the increase in the stiffness of ground soil under the same vehicle speed. There was a low-frequency amplification effect for ground vibration under the joint effect of earthquake and high-speed train loads

which was more obvious for higher speed and softer ground. The medium- and high-frequency ground vibration induced by combined loads was mainly affected by the train load. The ground vibration near the center of the track was greatly affected by the combined action of seismic and high-speed train loads

while that far away from the center of the track was mainly affected by the seismic load and less affected by the high-speed train load.