Propagation Laws Of Vibration Caused By Rail Transit In Lavered Soil

With the fast development of railway transport, especially the increasing coverage of urban area by the railway, noise and vibration caused by railway transport have an important effect on the surroundings. On one hand, noise and vibration in certain level will disturb people’s daily lives, influencing their emotions, rests, and studies; on the other hand, vibration would also result in liquidation and submergence or asymmetry submergence of the foundation, as well as wall crack, building inclination, and even partial damage. Particularly for those vibration-sensitive buildings, such as precise instrument plants, hospitals, laboratories, it will cause immeasurable losses. Thus, the issue of environmental vibration caused by railway transport is attracting extensive attention.The paper summarizes the current research on this topic home and abroad, elaborating systematically the achievements obtained regarding environmental vibration caused by railway transport. A train-track-embankment 3D finite element(FE) model through the software of ANSYS is established, then the vibration can be got by transient analysis. In the end, the interaction of track, embankment and underlying ground were analyzed from different views. It gives the rules of ground vibration attenuation and the assessments of vibration level. The result may provide theoretical foundation for the resign and use of Urban Rail Transit Project isolation. Specific conclusions have few points as followed:(1)A train-track-embankment 3D finite element(FE) model through the software of ANSYS is established, then we can make full use of the model to simulate the environment of Shanghai Metro Line Airport Extension. The model uses the viscous-spring artificial boundary and vibrating load is putted on it, using the half of the full model can save computing time and enhance the computing efficiency, it can also simulate the actual vibration of Shanghai Metro Line Airport Extension accurately.(2)In order to evaluate the effect of each Parameter on the ground response and its propagation features induced by moving trains, an different view of study was conducted, including the rules and assessments of vertical vibration acceleration changes in different directions, different measuring points and different train speeds. It also summarizes the variation of the vibration frequency.(3)Investigated and compared the effectiveness of three different vibration isolation measures, i.e.,open trench, in-filled trench and multi-row piles, with comparative approach, the paper displays the dynamic responses of three-dimension foundation surface in the circumstances of none vibration isolation and various vibration isolation measures. Besides, it also explains briefly the ranges of application of three vibration isolation measures, and analyzes the depth, width, thickness, as well as pile row of the above vibration isolation measures.