COMPARING THE DYNAMIC RESPONSE OF A LAYERED GROUND TO DIFFERENT TRAINLOADS

Abstract

The problem of ground dynamic response to a high-speed trainload has received much research attention in the literature, ranging from simplified analytical studies for elastic half-space to sophisticated numerical studies for layered or improved grounds. While most studies have focused on the dynamic response of a ground to a particular trainload, limited attention has been paid to comparing the dynamic response of a ground to different trainloads. In this study, we simulate the dynamic response of a layered ground to the passage of X2000 and Shinkansen trainloads. The obtained results are then compared to gain an understanding of how the ground responds to different trainloads. It is found that because the X2000 train and the Shinkansen train differ in carriage weights, carriage lengths, bogie distances and axle distances, they produce two trainloads whose magnitude and distribution of axle loads are different. As a consequence, they result in a difference in the surface deflection and displacement amplitudes. The difference in displacement amplitudes between the two train cases happens not only at the critical speed but also at all other considered train speeds (from 72 km/h to 360 km/h). On the other hand, although the X2000 train and Shinkansen train produce 2 trainloads that are different in magnitude and distribution of axle loads, they still result in the same critical speed of 252 km/h. This implies that the critical speed does not depend on the trainload type. Instead, it depends mainly on the specific wave propagation characteristics of the ground.