Train Induced Vibrations

Stupazzini, M., Paolucci, R., (2010). Ground motion induced by train passage in urban area, in Proceedings of ISMA2010-USD2010 Conference, pp. 3547–3558, Editors: Sas, P. and Bergen, B.

Paolucci R., A. Maffeis, L. Scandella, M. Stupazzini, M. Vanini, (2003). Numerical prediction of low-frequency ground vibrations induced by high-speed trains at Ledsgaard, Sweden, Soil Dynamics and Earthquake Engineering, Vol. 23, pp. 425-433.

Paolucci R., D. Spinelli, (2006). Ground motion induced by train passage, ASCE Journal of Engineering Mechanics, Vol. 132, n. 2, 201-210.

Introduction

The analysis of surface or underground train-induced ground vibrations a nd their effect on human beings and surrounding structures is of  paramount importance, especially for environmental impact studies of new high-speed train lines crossing urban areas. This problem is  particularly challenging and demanding from a computational point of view, since it requires to handle the dynamic interaction of train-track-tunnel-soil-structure.

 

Spectral element mesh for the simulation of train-induced vibrations in the case denoted by "u-s".

Spectral element mesh for the simulation of train-induced vibrations in the case denoted by “u-s”.

Numerical Model

A sketch of the sample problem considered in this study is shown. It consists of a eight-story building located close to a railway line. For sake of comparison and to show the capability of handling different configurations, we have considered the following cases:

  1. surface railway line (denoted by “s” in the following),
  2. underground railway line (denoted by “u”),
  3. the intermediate situation where the line is partly underground and partly located in a trench delimited by a retaining wall (denoted by ”u-s”).

Our objective is to study the vibrations induced in the soil and in the building by the passage of a two-carriages train, moving with speed c = 70 km/h = 19.4m/s.

Numerical Results

As an example of the results that can be obtained for this problem, we plot the snapshots of vertical displacement for the “u-s” case, at three different instants of time. We note that for relatively low train speeds, as is the case of this study, the ground motion amplitude decay with distance is fast, so that the building is practically unaffected by the train passage.

Snapshot of the vertical displacement at T = 3.5, 5.8 and 8.1 sec.

Snapshot of the vertical displacement at T = 3.5, 5.8 and 8.1 sec. The gray scale is saturated in order to show the propagating wavefield induced by the traveling load.