An overview of the basic concepts of vibrations from underground subway train

With the increase in population of cities and progress of technology, people demand toward a comfortable life has also increased. Traffic jams in big cities and shortage of parking lots have made necessary the need for use of underground spaces more than ever. The use of underground metro trains as a fast and safe vehicle could be appropriate alternative for passengers. However, movement of trains with appropriate speed in between stations produces vibrations that may sometimes be disturbing for people living in the region. These vibrations which are one of the most serious concerns related to region close to transportation systems could cause vibration of structures and hazardous noises inside buildings. In addition to hazard to human, these vibrations could affect old buildings and equipments. They could cause fatigue in the materials of ground and structure, create differential settlement, crack in walls, resonance and other difficulties. Therefore, in designing new rail road, evaluation of vibrations due to movement of trains is one of the important parameter in selecting the route and the type of rail system. In this research the vibrations in the ground surface due to passage of metro trains in city of Ahvaz metro under construction were evaluated.
By performing dynamic analysis on each station along the metro line and also using empirical method, the vibrations due to passage of train on the surface of ground were predicted and the regions that have high vibration potential are identified. Also the effects of different parameters on these vibrations were evaluated. The results show that in general the levels of vibrations in the northeast part of the route are higher than the southwest part. One of the most important factors responsible for this observation is the shallow depth of the rock and also soil profile in the northeast part of the route. Also the results show that utilization of new methods for damping vibrations cause a considerable decrease in the level of vibrations.