Propagation characteristics of vibration induced by medium-low-speed maglev train running on subgrade

Abstract

As a new generation of urban transit system, the medium-low-speed maglev transport entered a rapid development stage. However, the report about the ground vibration due to running medium-low-speed maglev train (mlsMT) is very limited. Therefore, an in-situ experiment and numerical analysis are systematically carried out to investigate the vertical and horizontal ground vibrations induced by mlsMT running on subgrade. The experiment was performed on the Changsha Maglev Express under different train load conditions. The numerical analysis is carried out by using the two-step analysis method. In the first step, the mlsMT-guideway spatially coupled dynamics model is developed to obtain the rail supporting forces during train passing. In the second step, a three-dimensional finite element model of guideway-subgrade-ground system is established, and then the rail supporting forces are taken as the external loads to calculate the ground vibration. After well validated by the experiment, the two-step analysis method is employed to study the time- and frequency- domain characteristics of the vertical and horizontal vibrations propagating from guideway to ground, under the conditions of different train speeds and double line operation. Results show that the vibrations induced by mlsMT are significantly different from those induced by the traditional wheel/rail steering train and the high-speed maglev train. The horizontal ground vibrations are not only more serious than vertical ones, but also have obvious vibration amplification phenomenon. Besides, the subgrade can obviously decrease the vertical and horizontal vibrations propagating to ground. With the increasing distance to the guideway centerline, both the decaying rate of ground vibration and the influences of the train load, running speed and double-guideway operation mode are gradually reduced. This works could contribute to the evaluation of the vibration annoyance caused by mlsMT operation.