Definition and analysis of ground surface vibration curves induced by railway traffic

Abstract

Prediction and control of ground-borne noise and vibrations are one of the largest environmental challenges for railway exploitation in urban areas. Empirical methods based on attenuation curves, similar to those presented by the Federal Transit Administration (FTA) and the Federal Railroad Administration (FRA), could be extremely versatile for a first estimative of the vibration levels at the ground surface. Despite the value of the presented curves, these have a generalist character, not allowing to attend to the particular and specific scenarios. Furthermore, both railway technology and construction techniques adopted in other world regions are quite distinct from USA reality giving rise to poor predictions when applied in distinct contexts. In this way, advanced numerical modelling is a reliable alternative, allowing incorporate the geological and geotechnical profile, type and geometric configuration of the railway track and railway vehicle specific to each case under study and, therefore, achieving a more elaborate level of detail in the analysis. On this work, a 2.5D FEM-PML (Finite Element Method – Perfectly Matched Layer) numerical approach is used to compute the ground surface vibration curves for different scenarios. From the results obtained, it is possible to state that, even being a conservative approach in some of the scenarios under consideration, the application of the empirical methodology proposed by FTA/FRA should be considered only as a first indicator, being recommended to perform more detailed analyses in situations that require a higher control of the permitted vibration levels.