سعيد حسني

In most metropolitans, where traffic congestion and the resulting environmental pollution are known as a source of hassle, subway trains are expanding as an effective means of transportation. However, vibrations induced by underground railways can reach to the level of annoyance for adjacent residents, disrupt vibration-sensitive equipment and cause damage in structures. Nevertheless, in order to avoid such problems, it is necessary to carefully eva‎luate vibrations and adopt the appropriate vibration mitigation solutions before operating the railway lines. Achieving this important matter needs complete understanding of different factors affecting on vibrations. As well as investigating concepts related to ground vibrations caused by subway lines in the source of vibration, this study also describes the path of vibration propagation and vibration receiver and other related concepts and prominent studies conducted in this field during recent years. Reviewing the past studies in the field of train induced vibrations show the consideration of flat soil profile on the top of the subway tunnel. It should be noted that in the field of earthquake engineering, influence of the ground surface topography on seismic waves have been investigated by various researchers. In response to this need, the present research is allocated to numerical study of the effect of the ground surface topographical changes in the form of a V-shaped valley on the subway-induced ground borne vibrations. In addition, the effect of geotechnical and operational parameters are investigated in presence of a V-shaped valley. All numerical analyses have been conducted by 3D ABAQUS software for Farahzad Valley in the northern extension of Tehran Subway Line 7. For validation purpose the developed FEM model results has been compared with measured field vibrations in Tehran Subway Line 7. In continue sensitivity analyses have been conducted on the valley angle, soil elasticity modulus, soil density and Poisson's ratio. The results of the V-shaped valley sensitivity analysis showed an increment in the ground surface vibrations level with the presence of a V-shaped valley above the subway tunnel, and the magnification will decreases with the increase of the valley slope. Moreover, the results show a decrease in the vibrations levels on the ground surface with an increase in the elasticity modulus and an increase in the soil density. Also, the results show the insignificant effect of Poisson's ratio on the vibrations response in compared to other geotechnical parameters. In the field of train operational parameters, the effect of train speed and train axle load examined. Also, the axial load increment of trains in each track or both, leads to an increment in vibrations levels.

مترو , راه آهن زيرزميني , ارتعاشات , ارتعاشات زميني , توپوگرافي , دره

subway , vibration , underground railway , vibration , ground borne vibration , topogeraphy , V-shaped valley

Saeid Hssani

Morteza Esmaeili