Urban railway ground vibrations induced by localized defects: using dynamic vibration absorbers as amitigation solution

Recent increases in urban railway track infrastructure construction are often delayed by distress to occupants caused by ground-borne vibration arising from the passing of the rail vehicle. Mitigation measures are proposed as a solution if they prove their efficiency in reducing these vibrations. In this paper, we present a practical study of dynamic vibration absorbers (DVAs) as a possible measure. A complete numerical study based on a recently developed two-step approach is performed. A detailed multibody model for the vehicle is coupled to a finite element/lumped mass model for the track in order to predict the forces acting on the soil. Then a 3D finite element model of the soil simulates the ground wave propagation generated from these dynamic forces to evaluate the level of vibration in the surrounding area. Having validated this model in the past, it is used to determine the effectiveness of DVA placed either in the vehicle or on the track. Compared to existing studies presenting DVA calibrations in terms of frequency response functions, realistic simulations are presented, based on the specific case of the T2000 tram circulating in Brussels traversing a localized defect. The results demonstrate that a DVA placed on the vehicle remains an interesting solution, provided that the mass is sufficient (mass ratio of 0.1).