A Hybrid Numerical-Experimental Assessment of Railway Ground Vibration in Urban Area

A common source of railway-induced ground vibrations is local defects such as rail joints, switches, and turnouts which cause large amplitude excitations at isolated locations along the track. Moreover, the distance between railway networks (tram, metro) and neighboring buildings is relatively close in urban areas. To analyze such situations, a combined numerical-experimental study is developed in this paper. The numerical approach addresses vehicle-track dynamics by considering the effect of local defects at the rail surface when a tram passes. A multibody vehicle model and a flexible two-dimensional track are coupled, which faithfully capture the interaction between the railway vehicle and the track. Field experiments are undertaken to determine track-ground dynamics. These involve measuring single source transfer mobilities between soil or building, and the force generated at the rail head, at the location of a local defect. The influence of building type and location is evaluated through experimental data collected in Brussels (Belgium). The results show that it is possible to assess vibrations from light rapid transit systems, while considering local rail defects as potential sources of vibration, and/or the complex paths associated with vibration transmission.